PO CKET

O p h t h a l m ic Dic tion a ry

INCLUDING

Pronun ciation , Derivation an d De fin itio n

O F THE W O RDS

USED IN

O ptometry a n d O phthalmology

T ogeth er wi th a comp l ete d escrip h h a v h eo tion of t e lig t w e t ry ,

n a t m f h E f un ct on s . A o y o t e ye, i bl ood a n d n erve s up p l y of th e d if f er n a r s e n os co e G h e t p t , R ti p , p th l mos o e r a a s e a n d h ow a c p , T i l C h em u s T ra n s os i s . e t o u e t . R l , p

n or a n d o h e n ses . t io , T i c t r l e a r s t on s S ta te b o d q ue i .

B I h D LEW S O . . AMES . y J J , p

Profes s or of O p t ometry in th e North e rn Illi n ois Col h h a o h ca o of t mo o a n d tol C . lege O p l l gy 0 gy , i g

FI FTH EDITIO N

Revi s e d a n d Enl arge d Ill us tra ted

C t 1 08 1 10 1 1 1 1 6 LEW S opyri gh , 9 , 9 , 9 3 , 9 , J. I . I To the P ro fe s s io n

i This e ditio n ha s be e n c o m p il e d w ith a g re a t

de a o f ca re Re a lizin a t e l . g th p rfe c tio n in its

full s e n s e ha s n e v e r be e n a tta in e d b m o ta a y r l m n ,

the a u th o r in v ite s the u n bia s e d a n d c o n s c ie n tio u s

c ritic is m o f th e re a de rs a n d us e rs o f this Dic tion a ry

a n d he re by e a rn e s tly s o lic its the s a m e t o th e e n d

tha t th e fu ture e ditio n s ma y p ro fit by the h o n e s t

c o n vic tio n s o f s tu dio u o c uli ts h i s s , p y s c ia n s a n d

O t t p o m e tris s .

I c a n n o t c o n c lude w ith o u t e x p re s s in g m y de e p

s e n s e o f o bliga tio n t o th e p ro fe s s io n fo r th e ir kin d

n w o e t s re c e p tio o f this rk . F e lin g he re p o n s ibility

d o s e h tte t o te h o the rs in c u rre by th w o a m p t a c , I h a v e s p a re d n o a m o u n t o f lab o r o r c o s t t o re n de r

i v o l m e e a r r tic a a n s e fu th s u c l , p a c l d u l .

e e tfu V ry re s p c lly ,

‘

THE AUTHO R . P R E F A C E

\ . l T O T H E F I F T H E D ITIO N

H E very favorable reception accorded the fourth edition of this work has encoura ged

the author to still further revise it , incorporating in its pages a considerable number of new d efin i

tions , as well as giving an accurate and complete derivation of all the technical terms used in of O ptical nomenclature , making the book the highest value to the practitioner and student

al ike .

In presen ting this fifth edition of the L ewi s

D ictionary and E ncyclopedia , I wish to express my appreciation for the invaluable assistance extended by

Mc F A I H M M J B . TR . . D . C , S

‘ P ro f e s s o r of t h e P rin cip l es o f O p h th a lm o l o g y a n d O to o g v.

LB A H M M F T R I D . GE O . WI UR C C , . ,

P ro f e s s o r o f C l in ic a l a n d D id a c tic O p h th a lm ol o g y a n d o o O t l g y .

M Y E M . H E N R S . T U C K R , A . , . D

‘ P ro f e s s o r o f A n a tom y a n d P h y s iol o g y o f t h e E y e u nr ra in B .

E E . B R DG M . . G TR O W I , . D ,

ro o D io ri P f es s r of p t c s .

J . J . L .

Abbreviation s an d O p tical Sign s

Accommodation .

Age .

Ametropia .

Anisometropia .

Astigmatism .

Asth Asthenopia .

Axi s .

Co. or ( minus ) Concave .

Centigrade .

Centimeter .

Cx . or ( plus ) Convex .

Cyl Cylinder .

D ioptry .

U . Cc D ouble concave . U . Cx D ouble convex . U T . D istance test .

H r E m . o E mmetropia .

D {. g . F or example .

H . or H y H ypermetropia .

In Inches .

L L . E L . or eft eye. M M M . or y yopia . M illimeter . N asal .

Nv Naked vision . D D t R 0 . . ( O culus ex er ) ight eye . L S . 0 . S . ( O culus inister ) eft eye .

n ti O . U . ( O cul i U a ) Both eyes .

P . or P b P resbyopia .

P . Cc P eriscopic concave .

P . Cx P eriscopic convex . i n — n Abbreviation s an d O ptical S g s Co .

- Inter P upillary di stance .

P l P lano . P p . p . ( unctum mum P rox i ) Near point . P p . r . ( unctum

R m tum F r e o ) a point . P rism . R R E R . or . ight eye . R eading test . P rescription .

S trabismus .

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 S pherical .

Temporal .

Type . V ision .

Visual acuteness .

Working point . P lus convex . M inus concave .

Combined with .

Degree . P D rism ioptry . E qual to . t 2 0 . Infini y , ft or farther .

' L 1 2 th ine , part of inch . P lus or ( and ) minus .

Centrad . M ultiplied by ; times . D ivided by .

Is ( or are ) greater than . [S (or are ) less than . Lewis O phthalmic Diction ary

Gr . . A. ( alpha , privative ) A prefix conveying a

f . negative m eaning ; a s w ithout , away , not , rom

’ x - - - A ba i a l ( a b aks e a l ) . Not situated in the line of

the axis .

e P E r ‘ A bb , rof . ns t . A German professor and in ven tor of an apparatus for measuring the ih

f 4 - d ices of re raction . 1 8 5 1 905 .

' b n a - - L A du ce s ( b du senz ) . ( . ab . from d ucere

to draw . ) The external rectus muscle , whose e action it is to rotate the eye outward . It aris s

by two heads , one from the lower margin of the sphenoidal fi ssure ; the other from the outer

'

margin of the optic foramen . Its tendon is ih

s rt d e e into the sclera 8 m m . from the outer

margin of th ecornea . Under normal condition s these muscles should overcome about 8 degrees \ ,

of prism a s e in . It i s controlled hy the sixth , b

pair of cranial nerves ( abducens ) .

’ - - n A bdu c ent ( a b du sent ) . Ad Cti g ; drawing from

the center . = d cere t . A bdu ct ( ab away , u o lead ) To draw

away from the m edian line .

’ - - A bd uct ion ( a h duc shun ) . The act of turning the

eye outward from its position of rest . F or test ing the power of the abductors or external rec ti t muscles , use the strongest prism , base in , wi h

which th e eyes can overcome diplopia , looking

2 . 0 f eet away , and deduct any imbalance 8 L E W ’ IS P O C KE T

’ - -t b d c t or ah or . t A u ( duc ) Any muscle hat abducts .

F or instance , abductor oculi , the external rectu s

muscle .

’ t n h - er- - L z b e r a a a . A r io ( shun ) ( . ab away , errare

to wander . ) Wandering from normal . When

applied to lenses would mean , unable to obtain

a perfect focus . It i s due to the greater retrae tive power of the edge over the center of convex

lenses , thus causing the image to be somewhat th e ff blurred. In the eye iri s shuts o the edge of w the lens , and in this a y prevents spherical

t rr t aberration . Ch rom a i c A b e a ion , dispersion of ff colors . O wing to the colored rays having di er ent degrees of retractibility they are not focused

at the same d istance .

’ ’ ------L b h in . a A b l atio retin a e ( a la she o ret e ) . ( z away + l atum to take . ) D etachment of the

retina .

r zih -b l e f Gr A bl e p h a i a ( ( . a not z b l ep h aron ey el id . ) That condition in which

th . b e a r us . e eyelids are absent Also , A l p h o

’ - - - Gr bl e o A bl e p s i a ( ah hl ep se ah ) . ( . a not p — B . I see . ) lindness want of sight

Abn orma l (L . ab away normal rul e ) . Away

from normal . R elating to vision would mean ,

m t r . any defect of sight . (A e o p ia ) An eye wherein parallel rays of light do not focus on th e retina with th e muscles of accommodation

a t rest .

’ ’ - - - - o - - n e- L A b ra s io c o rn ea ( ah ra si cor ah ) . ( . ab

away radere to scrape . ) The rubbing off of

th e outer layer of the cornea .

’ - 1 L . A b s c es s ( ab ses ) . ( ab away cedere to O PHTHALM IC DI C TI O NARY 9

depart . ) A collection of pus in any cavity

formed by the separation of tissue .

’ - - bs c s b a . A i s a ( a sis ) . ( L . cut off ) A certain l ine used in determining the posi tion of a point i n a

plane .

’ Abs r t - - L r a h . s o b e re o p ion ( sorp shun ) ( . ab , and k to suc in . ) A term applied in the operation for t ca arac t where th e lens capsule is needled ,

allowing th e aqueous humor to absorb the lens .

A bs o rpt i v e . Anything that has the power of a h

sorption .

’ A bs t ra ct a - r k r t = d r w n ( h s t a t) . ( L . a bs t a c us a

away . ) An abstract number I S a number not designated a s referring to any particular class

of objects .

e r t A cc l e a ion . An increase in rapidity ; oppose d to

retardation .

’ ’ c o m da t k - - - - c L . a o A m o ion ( a kom mo da shun ) . (

commodare to d epart . ) The act of adjusting

the eye to see w ithin its far point of Vis ion . O ptical adjustment . It takes place by contract ing the ciliary muscl es which encircle the crys tall in e lens and draws forward the inner layer

of the choroid and hyaloid m embrane , the sus

p en sory ligaments becoming relaxed , and the lens ( by its own elasticity ) allowed to assume

a greater convexity , especially its anterior sur

face , thus increasing its refraction . It is never used unless the light attempts to focus behind m t th e retina . Amp litu d e of A ccom o da ion is the difference i n th e dioptric power of the eye when in a state of complete rel axation and when the

full amount of accommodation is in use ; or , in

o ther words , th e amoun t of accommodation an 1 0 L E W I S PO CKE T

eye possesses . Ampl itude of Accommodation at

different ages ( from L andolt ) as follow s :

This is approximately correct , b ut individuals diff er in th e amount of accommodation they t possess at the same age . Accommoda ion i s

v . spoken of as binocular , absolute , and relati e

Bino cul a r A c c ommo da t ion is the full amount of accommodation which both eyes can use

together while converging . A bs olut e A cc ommo dation is the total amount t of accommodation of one eye only, the o her

being covered . Rel a t iv e A c commodat ion is the amount of accommodation that can b e used without chang

ing the convergence ; that is , by lenses or other

means .

S p a s m of A c c om mo da tion, the inability on th e part of the patient to relax his accommoda

tion without drugs . O P H THALM I C DI C TIO NARY 1 1

C ente r of A cc om moda t ion is situated b eneath

the floor of the aqueduct of S ilvius .

P a ra ly s i s of A c commo da tion is the loss of power of movement in the ciliary muscles

through injury , disease , or a drug affecting the

nerve supply . Nega t i ve A c c o mmo da tion would m ean that the eye possesses the abi lity to decrease its dioptric power from that which it possesses in B a state of rest . y so doing would lengthen its

principal focus . Accommodation is interfered with by harden

ing of the lens , weakness of the ciliary muscles ,

paralysi s of the third nerve , loss of the crystal

or line lens , use o f drugs , such as Atropine .

h l r A chlo ro p s i a (Gr . a without c o os green

i G - op s s vision ) . reen blindness , color blind

ness as regards green .

’ m ak - - A ch ro a ( ro mah ) . (Gr . a not chroma

color . ) Without color .

’ - - - k L A c h rom a ti c Len s ( ah kro mat i ) . ( S ee ens . )

’ - - - i m A ch rom at i s m ( ah kro m a t s ) . Absence of eb ro

ma tic aberration .

’ - — - - Ac h roma t is tous ( ah kro mat is tus ) . Deficient in

coloring matter or pigment .

’ r a t s - - -o - - G r A c h om o p ia ( ah kro mat p se ah ) . ( . a h = r m l or . lacking , c o a co , eye ) Total color

blindness .

’ - - - - A ch rom ato sis ( ah kro mat o sis ) . Any di s ease

of marked by lack pigmentation .

’ - - - u k r . Aco rea (ah o re ah ) . ( G a not kore p

pil . ) When the pupil is absent . 1 2

c ed. N o t w t b u v t e A q uir born i h . t d e eloped a f r

birth .

' c t k - - - ) a u it e . l . r t . A ui y i ) ( . a c ue e o s harpen

S s s f . s s o harpne , like a needle The harpne s

v s th e i ion ; keenne s s of th e vi s ual powers . The acu tene s s o f v i s ion mean s th e vi s ion th e pa tien t

h a s t h is f c t t y t e wi h ull corre ion . The facul of h re tina to percei ve form s d e pend s on many con

d ition s :

. P th e s s b t o f th e t . l rimarily . on en i ili y re ina th t 2 . n t O e adap ta tion o f h e re ina . O 3 . n t the general illumina ion . t . O 4 n th e s harpne s s of h e re tinal ima g e .

O n th t s t o f th e t . 5 . e in en i y illumina ion

I t is kno wn tha t th e acu tene s s o f v i s ion varie s w i th th e g eneral illumina tion up to a c e r ta in

o f t s t s t t o f a s un n v d egree in en i y . a ha a cle r ,

t w t v d e t t day ; h e t o hen ary i n a ir c pro po r ion . b ut when t h e illumina tion pa s s e s a cer tain limi t

o f t s t y th e c t s s o f v s d s e s in en i . a u ene i ion i mini h

s t d o f i c s s in ea n rea e .

' - - t - i t re to l . . d a a A da p ta t ion ( a d a p a s ln in i. a p

t s t t o f th e I n t . adap . ) Adju men pu p il li g h

' ~ - ) ( I dd e re t s e . A ddi tion in d ish o n ) . a o increa The uni tin g o f tw o or more num b ers in o n e

s um.

t w d s d a A d d uc c n s ( a d ( l ad o ar .

o \ u t s t is e d t o c ere to l a d . ) t h i erm a p p li

e e c t s c th e. th e e y it m an s th e in tern a l re u mu s le . mu s c le whi c h turn s th e eyeba ll in ward to ward

t th e t c n t h e no s e , s upplied by hird ra ial or mo or

T e w dd t t h e e e o c n ll nerve . h po er o f a uc ion of y

0 530 e F r t s t ranges from 2 up to d g ree s . o e ing

th e pow e r o f th e a dd uc e n s or in te rnal re c tu s O PHTHALM I C DI C TIO NARY 1 3

t muscle , use the strongest prism , base out , wi h

which the eyes can overcome diplopia .

L z A dduct ( . adducere to bring toward ) . To draw

inward toward a center .

A dduct io n . Movement of the eyeball inward from

its position of rest . Th e a dducen s means the internal rectus muscle by which w e turn th e

eyes inward . The test for the power of the a dduc en s is made by fi rst correcting any error of re fraction and have the patient look at a

2 0 e th e light f et away , placing the base out of

strongest prism , with which the eyes can over fi come diplopia . We gure from their position of

rest and this prism registers the adduction .

‘ ’ - - - n z n Ad en ecto my ( a d e n ek to ( Gr . a de gl a d _

ek tome excision . ) R emoval of a. gland b y

operation .

d n m r x s Gr — A e e p h a i ( . aden gland i emphraxis

or stoppage ) . That condition in which the duct

gland i s ob structed .

’ d e d - n - ld r edoi A noi d ( a e o ) . ( G . aden gland s

appearance . ) R esembling a gland .

’ A d e n ologa dit i s ( a d - en - o- log- a d - i Inflammation:

» of th e glands of the eyes and conjunctiva . Gp h l t h a mia neonatorum .

’ - - ff- - - e A e n t m d u . r d o ph ha l i a ( a e o thal me ah ) (G . ad n

gland op h th a lmos eye . ) Inflammation of

the meibomian glands .

’ “ - - t a d i L . A di u s ( tis ) . ( . a passage The entrance

t b ta e to a canal or duct . Adi u s O r i , the openin g

of the orbit , covered by the eyelids .

of Adva n c e me nt . The cutting away of a muscle

'

the eye and attaching it to an a dvanced point . 1 -1 L E IVI S PO C KE T

This operation i s performed on th e weak muscle

in cases of strabismus .

’ v e t t s a d - - - — A d n i iou ( ven tish us ) . Acquired not nor

mal .

ff t e re L . f A n ( ad to erre to bear ) . Convey

th e to t ing from surface the cen er , as a nerve

or vein .

’ b s l - - = a . l L . a b s Al ini m ( bin ism ) ( u wh ite . ) A h normal deficiency of pigment i n th e iri s a n d

choroid .

’ l - - Al bugo ( a b u go ) . White opacity of the cornea

of the eye . L eukoma .

’ A - - e a . Gr. a 3. l xi ( lex ia ) ( lacking , lexia word . ) U nable to read , due to a central lesion .

’ a r s m- w - r - z s a a o . r ma urotin G . a to Am u o i ( sis ) ( .

render obscure. ) A disease of the opt ic nerve n or reti a , which causes blindne s s .

’ b a a m-b e - - - r o e . G . t Am iopi ( p ah ) ( ambo bo h .

O . p ia eye ) Vision with both eyes .

’ b a m- - - e Gr a mbl s z b l un t Am lyo p i a ( ble o p ( . y

op s is sight. ) A dimness of vision from de

fective sensibility of the retina . A condi tion in which there i s a possibili ty of res toring the

former vision ; for instance , when a person ha s

e an error of refraction in one eye , th other eye

being emmetropic , h e will l earn to ignore the h eye with the error , and use th e one wi th t e

best vision . In this way the sight will become d im a from w nt of use , and is an acquired state . which by testing with th e pinhole disc will show

th e no improvement . Under these conditions , t error must be corrected wi th the re inoscope , and if the eyes are not more than two dioptries O PHTHALM IC DI C TI O NARY 1 5

apart , instruct your patient always to wear his correction and cover the good eye two or three

r times a day , fo a period of ten m inutes at a

time , and try to use the amblyopic eye . In this way you will notice an improvement of vision

i im each week . When the pinhole d sc fails to

prove vi sion , the eye is either amblyopic or in

x a diseased state . T o i c Am blyo p i a is a dimness

of vision from the poisonous effect of drugs ,

such as quinine , upon the nervous system ; ex c es s ive use of tobacco or alcoholic stimulants

produce the same effect . The treatm ent for this

form of Amblyopia does not consist of glasses , but th e patient must quit the use of the drug

causing the trouble , and if not too far advanced

' there is a possibility of recoverin g the former

vision . that due to sexual ex

- cess . A . , C ro s s ed, on one half of retina .

m l A b yo p i a ex Ano p s i a . Amblyopia resulting from one eye having been excluded for some time

from binocular vision .

’ A et r t ~ - - - = m om e e r ( a met rom e ter ) . ( Gr. a lacking

metron measure . ) An instrument used for

measuring ametropia .

’ Amet r - - r - - o p ia ( a met o p e ah ) . ( Gr. lacking ,

: 2 metron measure , ops eye . ) Any error of

refraction , such as hyperopia , myopia , or astig m atis m . x m A i a l A et ro p i a . Ametropia that i s caused by the length of the eyeball on the optic

axis . The opposite of E mmetropia .

Am ’ p hi c e lo us ( Gr . amphi on both sides koi

‘

los hollow ) . Concave on both sides or ends .

' ’ Am d m- f - - - - r p ho i p lo p ia ( a o dip lo p e ah ) . ( G . ampho 1 6 LE \ V I S PO C K E T

di l both p oos double . ) That conditio

where both eyes have double vision .

’ m - - - A p lifi e r ( a m ple fi er ) . An apparatus for i creasing the magnifying power of a micros cop

’ m t - - A p li ude ( am pli tud ) . S tate of being a mp l ( P hysics ) The extent of a movem ent m ea from t h e starting point or position of ( Math ) An angle upon which the value of som

function depends .

m t n v ude of e r e . A p li Co g n c e ( S ee Convergenc e . )

’ m s ta s Gr A yo i a ( . a not mys muscle sta

' r m ' s sis standing ) . Nervous t e or of the muscle .

’ m t n r A yos h e ia ( G . a not mys muscle sthe

1 F nos strength ) . ailure of muscular strength .

’ A n a ca mptom et e r. An instrument for m easuring

the reflexes .

’ A n h - k - - Gr ac a s a a . l i s ( las is ) ( . bending back , re

fl ection . t is i ) When this erm applied to l ight , t refers to the rays traveling obliquely from a

in edium rarer to a denser , being bent backward

toward the perpendicular ( refraction ) .

’ - - - - A n a es th es i a ( a n es the ze ah ) . ( Gr . an not L t a is th es 1 s sensation . ) acking sensi iveness ,

where the retina i s amblyopic .

’ - - - k A n a es th eti c ( an es thet i ) . The name given to t that which produces insensibili y to pain . as

chloroform , cocaine , and ether .

’ - - - A i . . na lys is ( a nal sis ) . (Gr a releasing A reso

‘ l a tion of a whole into its parts ; a form of

reasoning from a whole to its parts .

’ - - -i A n a pho ri a ( a n a phor a) . (Gr . ana up phoria th e tending . ) That condition in which eyes turn upward when the extrinsic muscles are in l b PO C K E T

w t t its f a ch crys al is placed i n rame . and is com v w w po s ed o f fi e layers , from i thout in ard a s

' f : t v E t s ollows Conj unc i a pi helium , Bowman M P M of D embrane . Co rnea roper , embrane esce h E th met t e t . e . and ndo helium At inner angle ( angle of fil tra tion ) between th e iris and cor

t - s nea . here are a number of comb like opening which e i n th e trabecular tissue or pec tina te

l igamen t which runs from th e peri phery of th e

e cornea to th ba s e of th e iris . These openings

th e F t are called spaces of ontana . hrough which th e aq ueou s humor pa s s e s in to th e canal of

S d th e chlemm , a circular canal extending aroun periphery of th e cornea at th e s clero cornea l O PHTHALM IC DIC TIO NA R Y 1 9

t junc tion . F rom this canal the humor passes in o

the an terior ciliary veins . The second tunic of

s the eye i s compo ed of the choroid . c iliary body .

. o f l and th e iris . l t l ines the inner side the sc e

s to w th e t rof i e . and i perforated al lo op ic nerve t to en ter . a n d has a circular opening in fron ,

Ven n M i mosa

CILlHRY BO

‘ t ut s h o w in S e g con d T un ic .

w s t hich is known as th e pupil . Through thi uni c the eye ob tains its princi pal blood and nerve

supply . This is the tunic i n which the pigmen t th t is deposited for e purpose of absorbing l i gh . The choroid is said to nouris h th e retina and

t th e the vitreous . The c iliary muscles are w i hin

are for t . ciliary body , and used accommoda ing The iris i s the most an terior portion of th e

t o f s second tunic . It i s located i n fron the cry

t t os alline lens , and separates the an erior and p

t ri r . e o chambers ; it gives the. eye its color ,

regulates the amount of li ght which en ters , and

prevents spherical aberration of th e lens . The t t t . it hird unic is the . retina i s a very delica e

s e n tran parent membrane . made up of t layers .

one of which i s the layer of op tic nerve fibers . The s e fibers pas s through th e lam ina cribros a

a t . t tt out . the op ic d isc . and fla en more and more ‘7 0 L E \ V I S P O C KE T

L A R D T H RO U G H C I I Y B O Y. C C o r n e a S c l S c e r o t ic C h C h o ro id R R t in a or O r a , ; , l ; . ; , e ; , S rra t a Z Z Z i o r n o r L i a m e n t s e ; . o n u l e o f n n S us p e s y g ; ’ ii P a n a i P t h m o s t ro m i , e t it s C l ; E d g e o f P up l ; , e p n e n t a r i i r ro e s s s h in t e r P u i ae p t o f t h e C l a y P c ; p , S p c p ll M us c e 8 a n a o f c e m m L C on un c t iv a L e n s l ; . C l S h l ; , j ; B , ; 1 A n l e o f il t r a t io n . g F O PHTHALM I C DI C TI O NARY 2 1

as they approach th e front of the eye . The

retina is attached in two places , at the optic t t disc and at its an erior border , the ora serra a .

I t i s not attached to the choroid , but simply lies h th l on it . In examining the retina with the op a mos cop e you will notice the optic disc on th e

nasal side , which marks the entrance of the l . optic nerve into the g obe The macula . lutea , which i s the most sensitive spot of the retin a

( sometimes called the yellow spot , as it i s said t h t to turn yellow after death ) , i s situa ed slig ly

th e on temple side . The function of th e retin a i s to receive the impressions of the waves of l ight and transmit them through the optic nerve t o the brain . The space between the i ris and

cornea is known as the anterior chamber of. the

eye , and that between the iris and the lens , as

the posterior chamber . Both of these ch ambers

are filled with a transparent , watery fluid known k as the aqueous humor . The large chamber bac of the crystalline lens i s known as the vitreous

chamber , and contains the vitreous humor ,

which occupies a little more than three - fourths

of the eyeball . It is a perfectly transparent sub

stance , about the consistency of the white of an

egg , and i s enclosed in a thin transparent sac

known as the hyaloid m embrane . Thi s m em brane divides at the ciliary body and form s what i s known as the anterior and posterior

suspensory ligaments , which are attached to the l a s ens capsule , thus forming what is known ’ t P eti t s Canal and th e Z onule of Zinn . Wi hin th e len s capsule th e crys ta ll in e ‘ l e n s is to b i be found . In shape th e l ens resembles a

t t it s in convexed lens , excep hat i s l es curved 2 2 LE W I S PO CKE T

t front than behind ; in you h it is highly elastic ,

moderately firm , yet a perfectl y transparent e body , as clear as a crystal , and as w grow older it b ecomes harder and sometimes of a

slightly straw tint . The crystalline lens is made up of layers closely resembl ing those of an t onion , which accounts for its elas icity . The eyeball is imbedded in the fatty ‘ substance of

th e orbit , and is surrounded by a thin mem

b ra n ous sac , which isol a tes it and at the same

- time allows free movement . This sac is named h t e Capsule of Tenon . It is a very delicate

in membrane , consisting of two layers which vest the posterior part of the globe from the margin of the cornea backward to the entrance t of the optic nerve , and is connec ed to it by a

very delicate connective tissue . Both layers are

l ined on the inner surface by endothelial cells . The cavity b etween them is continuou s with

“ the S pace between the two layers of th e sheath

of the optic nerve , which is known as the sub

arachnoid space . The inner layer i s known as

the pia mater , and the outer as the dura mater , and between them empty the lymphatic vessels t of th e sclerotic . This capsule is pene rated by th e (tendon ) muscles of the eyeball near their

a n d insertion , which spread out fan shape are

attached to the sclerotic .

’ - - - A natomi s t ( a nat o mist ) . A person who i s skilled

in anatomy .

t m Ana o y of O rbits . S ee O rbit .

’ t Gr Ana ro p ia ( . ana up trope a turning ) .

That condition in which the eyes turn up .

Angl e . A figure formed by two straight lines ex tending out from one point in di fferent direc O PHTHALM IC DIC TIO NARY 2 3

t n tions . A cu e A gle is an angle less than a right

angle , or less than 90 degrees . A dj a c ent or Conti guo us angles are such as have one l eg

A n le common to both angles . g Al ph a is the

angle formed by the optic and vi sual axis . Angul a r Ap ert ure is the angl e formed at the focal point of a microscope by the most diver g en t rays which enter the obj ective lens . Angl e

of Conv e rgence is the. angle which the two visual axes form in turning from their positio n of rest to a point less remote . The angle formed by the eyes turning from parallelism until th e visual axes are directed to a point one meter distant on the median line , i s called a meter angle of convergence and i s the unit of th e angle of convergence . When the visual axes

~ meet on the median l ine , at a half meter dis

- n tance , it i s called a two meter angle of co

m r vergence , and when looking at a third ete distance it is called a three - meter angle of con vergence . C rit ica l Angle i s the angle b eyond which a ray of light passing from a higher to a less refractive medium cannot emerge . Angl e of Devi a tion i s the angle formed between th e

direction of the incident and emergent rays ,

A n and shows the total deflection . gle of Ga mm a is the angle formed at the center of rotation of the eye by the optic axi s and a line drawn from the point on the object looked at . It varies with

n d the refraction of the eye , a in emmetropia is about it increases in hyperopia and

n decreases in myopia . Angl e of I ci d en ce is the angle formed by the incident ray with the per

n i r p e d cul a at the surface . Angl e of l ris is the angle b etween th e iri s and the corn ea at the 2 4 L E W IS PO C KE T

o f th e t periphery an erior chamber of the eye .

M et e r A n le t M g ( for descrip ion , see under et e r

A n le M ut A n l v g ) . in e g e is an angle formed b tw o straight lines that have traveled twenty

feet distant from a point and separated th e t sixtie h part of a degree . O bliq u e Angl e i s an

angle a cute or obtuse , in opposition to a ri ght O t angle . b us e Angl e is an angle greater than a

r ight angle or more than 9 0 degrees . O pti c Angl e i s the angle included between the optic a x es of the two eyes when directed to th e sam e

point . A n gle of P ri s m is the angl e formed by th e surfaces of the prism which incl ine to each

A n l R f t d other . g e of e l ec ion is an angl e forme by the reflected ray with a l ine perpendicular t t o the reflecting surface , and is always equal o

R t i is th e Angle of Incidence . Angl e of ef ra c on th e angle formed by the refracted ray with th e R t d perpendicular . i gh Angl e is an angle forme by a right line falling on another p erp en dicu

l A l S t ra arl 0 . n e y , or an angle of 9 degrees g of b is mus i s th e angle formed by the deviating eye

V A n l e th e w ith that of its fellow . i s u a l g is angle form ed between straight lines drawn from th e boundaries of th e object looked at and

crossing the optical center of th e eye .

’ A n i t i Gr ia n th in os z a n h n op s y ( . an not violet t colored op s is vi sion ) . Inabili y to distin

g uish violet shades .

’ - - - - r. . Ani ri di a ( ah ir id e ah ) . (G an not iris )

Congeni tal absence of the iris .

’ - - - - - = ~ r . n is os un A n i s o c ori a ( an is o k o re ah ) . ( G a t t equal koro pupil . ) Tha condi ion where

th e two pupils are unequal .

2 G LE W I S PO C KE T

' n t ah - - - me - r n z n A o p h ha lmi a ( off thal ah ) . ( G . a ot

lm s . op hth a o eye ) Absence of the eyes .

n a Gr A o p i ( . an without ops

eye ) . Congenital absence of the eye , or eyes .

’ s a ah - - - Ano p i ( op se ah ) . (Gr . an not op s is

. D e t sight ) isus of the eye from certain defec s ,

such as cataract , amblyopia , and high refractive

errors .

’ An rt - - - - = h r . o ho p ia ( a o tho p e ah ) . ( Gr an not +

orthos straight ops eye . ) A defective state of vision which is unable to distinguish a

want of parallelism .

n t r A e io r ( front part ) . R eferring to the eye , the

cornea would be the most anterior point .

’ n t m t r - - - - - A i e o p i a ( ah ti me tro p e ah ) . ( Gr . anti

opposite , m etron measure . ) Where one eye

is myopic and the other hypermetropic .

’ An t h - - - r n ti z in G . a a a st ti s ep i c ( a ti sep tik ) . ( g + o septic putrid . ) A substance which i s destru t ive to poisonous germs .

’ — - i = r r r t . Ao ta ( a o ta ) . ( Gr . a e o o lift , raise ) The

great main trunk of the arterial system , pro

n t ceedi g from the left ventricle of the hear , giving origin to all the arteries except the pul

mon ar y (lungs ) .

’ - z . Th h Ap ex ( a p e ) . or tip ) e t in edge

of a prism .

A pha ci a . S ee Aphakia .

’ - - - = k f k e Gr. a l ack in h ak os A pha i a ( ah a ah ) . ( g , p

lens . ) Absence of the crystalline lens .

A ph os e ( ah (Gr . a without phos

light . ) Any visual sensation due to absence or

interruption of light . O PHTHALM IC DI C TIO NARY 2 7

’ ca a - P Ap i l ( pik ertaining to the apex .

’ — - - - ik a a t c a t Gr . A p l n i (ah plan ) . ( a not plane

z n rin tos w a d e g . ) That condition where there

i s neither spherical nor chromatic aberration , ‘ L and the lines are also straight . ( S e e ens . )

’ - u- - r - r n e r s s a o u o . G A po u o i ( p sis ) ( . apo from z neuron sinew . ) A fibrous band investing mus

cles and connecting them with tendons . It is

white , fibrous , and destitute of nerves , and has

very little blood .

A p p a rent P o s itio n . The position apparently occu pied by an object seen through a refracting

medium , as distinguished from its real position .

n t E A p p e da ges of h e ye are the orbits , the eye

brows , the eyeli ds , the conjunctiva , the lach

th e rymal apparatus , muscles , the aponeurosis ,

and vessels and nerves of the orbit .

’ ’ ------Ap p la n at io co rn ea e ( a p lan a she o kor n e e ) . A

condition in which the cornea b ecomes fi ato

tened .

' — t n L ad . A p p l a na io ( . to l planare to flatten )

F lattening of a normally convex surface .

’ - - - - L a d = to Ap p rox ima ti on ( a prok si ma shon ) . ( .

a ‘ p rox ima re to come near . ) A continual p

proach to a true result . A result so near the

truth as to be suffi cient for a given purpose .

’ ’ - - - L Aq u eou s H umo r ( a que us h u mor ) . ( . aqua

: w . ater , humor moist ) A transparent , watery fluid which fill s the anterior and posterior

chambers of the eye , the iris becoming the

boundary line between the two chambers .

Weight , 5 grains . Composed of water , albumen . n and salts . The aqueous i s a secretio formed by 2 8 PO CKE T

' th e epi thelial cells lining th e apice s o f th e cil

ia r n y processes . pa ssing through th e pup il a d

’ lea v ing th e ey e t hrough S chl emm s Canal t o pa s s

y into th e an t erior ciliar vein . I f thi s humor is

l s allow ed t o escape it will r e form again . t index of refraction i s

' ' - - - - - ca s t k w . i n Aq uo p uli i s ( a o c aps u l i t s ) . S erous i

fl a mma ti n h o of t e iris .

' ra - k - y w c d a ) . G r A hnoi ( ar no d ( . arachne cob eb .

’ i = r e dos es emb l a n ce . ) R esembl ing a s pider s w e b .

A ra c hnoi d M e mb ra n e is a nam e g i v en t o

s v w y xt e eral membranes hich . b t heir e reme

w Th e d t fineness . resembl e spider ebs . elica e membrane betw een th e dura ma ter a n d p in

ma t er of th e op t ic nerve and cap s ul e of t enon .

S u ba ra c hnoi d S p a c e is loca ted b et w een th e I t a rachnoi d m embrane a n d th e p ia ma t er .

contain s th e greater part of t h e cerebro - s pin a l

fluid .

S u b dura l S p a c e is located bet w een th e dura

a n d m ater and th e arachnoid membrane . con d t ains a small amount of subdura l flui .

The use of th e subarachnoid or cerebro - spinal

v flui d is t o m echanically prot ec t. t h e ner e cen

t t a s fa t ers from s hock , and o fil l up space . does

I t s t is s t in o ther part s of th e body . amoun e i w ma t ed a t l ess than t o ounces . A = w ) rc ) . L b . (ark ( . arcus o A portion of a

v cur ed line or segment of a circle .

’ ’ - - - i L s b w r . o . A c u s s enili s (ar kus sen il es ( . arcu

s enilis old . ) Whi te ci rcle in cornea near

tw o s clerotic . The arcus is first noticed as

s t v th e mall white opaque crescen s . one abo e and O PHTHALM IC DI C TIONARY 2 9

t the o her below within margin of the cornea , gradually ex tending until the ends join, form

ing a ring . The arcus will increase in opacity

more than in width , and the cornea remains perfectly transparent within its circle and vision

is not impaired by it . Cause , fatty degenera

tion . Condition in aged .

‘ A rea of C rit i ca l Definit io n . That portion of an optical image within which the detail is clearly

defined .

’ r a - - - - - A g m blyo p ia (ar gam ble o p e ah ) . Amblyopia

f - rom non use of eye .

r - R A gyll o b e rt s on P up il . A pupil that will not re s on d t p o light , but contracts in accomm odation .

- Can be seen in locomotor ataxia .

' r t et c a - - - m : n m A i hm i ( rith m e tik ) . (Gr . a rith os u

h er. t ) The heory of numbers , the art of com t th puta ion , and e applications of numbers to

s cience and business .

’ t r - r te . Gr . Ar e y ( ar y ) ( . tube ) The vessel which carries th e purified blood from the heart to th e

di fferent cells of the body . The ophthalm ic ar t ery supplies th e eye with blood and it arises ‘ from the internal carotid artery at the anterior

clinoid process and i s about one - twelfth of an

inch in diameter . It enters the orbit through the optic foramen below a n d on the templ e side

of the optic nerve . It then passe s over the nerve to the inner wall of the orbit and runs it forward to th e inner angle of the eye . where

divides into th e frontal and nasal branches ,

which may be divided into an orb ital group . It

h - give s off t e lachrymal , supra orbital , anterior

t al . and posterior e hmoidal . palpebr frontal and 3 0 LE W IS PO C KE T

th e nasal , muscular anterior , short and long

th e t ciliary , and central ar ery of the retina . The short ciliary arteries ( six to t en in num ber ) enter the eye through the sclerotic around th e optic nerve to supply th e choroi d and cil iary

p rocesses . The long ciliary arteries ( two in number )

p ierce the sclerotic , one on each side of the eye , and run forward between the cho ro id and the th sclerotic to e ciliary muscles , which they sup t ply , and hey join the anterior ciliary arteries . Th e anterior ciliary arteries ( five to eight in number ) are derived from the muscular and

' l r n achrymal b a ch e s of the ophthalmic . They penetrate the sclerotic about a sixteenth of an

inch from the corneal margin , and finally join the long posterior ciliary arteries to form the

r circulus arteriosus iridis majo . The arteria centralis retinae is the first and one of the smallest branches of th e ophthalmic

artery . It pierces the optic nerve about half an inch behind the eye ball and runs forward to

th e retina , in its centre , entering the eye h through an opening in t e lam ina cribrosa ,

known as the porus opticus , where it divides

into four branches .

f E A rt i ic i a l ye . A thin glass plate which resemble s

the sclerotic , cornea and iris . Artificial eyes f z are made in di ferent si es and colors , and are

always fitted to match the sound eye . Before inserting the artificial eye it should be put into t salt and water for a few minu es . then draw the

th e upper lid out and down , and slip eye up

under ; then draw the lower lid out and down ,

“ and in this way allow the eye to fall into posi O PHTHALM I C DI C TIO NARY 3 1

B L O O D V E S S E L S O F

X h . T e b l a c k l in e s r ep re s e n t v e in s l e a v in g t h e e y e a s An t e rior C il ia ry V e in s ; s h o r i c c , t C il a r y Art e rie s ; ( 1 on i , l g C il a ry A r te r y ; C o , C orn e a L L e n s i i r ; , ; g , C l a y B o d or O ra rr a y ; , S e t a ; R , R e c tus M us c l e ; B , C o n j un c tiva ; p , C o n j u n c t iv a l v e in s ;

O p tic S h e a th . 3 -2 L E W I S PO C K E T

tion . As a rule , an artificial eye will last about

a year , when it begins to lose its smoothness

and a new one is required .

t f P n Ar i i c i a l up il . O e made by an operation ( Iri dectomy )

’

s e s s . F A p i ree from septic matter , or free from

infection .

’ s t e - - - - z k a o . r l in A h no p i ( as then pi ah ) ( G . a a c g ,

t t s s henos streng h , op eye . ) Weak , tired and painful vi sion ; th e result of s training some h part of the mec anism of the eye . Vision may

be normal . It is subdivided into three kinds : t retinal , muscular , and accommoda ive .

Ret in a l . Where the eye cannot stand l igh t

without pain ; intolerance of light ; photophobia . M t u s cu l a r. A condi ion of th e eyes i n which th e muscles controlling their movement suffer

from speedy fatigue , causing pain .

m v A c co mo da ti e . F atigue of the ciliary mus

'

cles by hyperm etropia , presbyopia , or overwork

in emmetropia .

’ A s t i g ma g ra ph ( as - tig - ma An instrument used to demonstrate the state or condi tion of

astigmatism of the eye .

’ - - - = m m r. As t i g a t i s ( as tig mat ism ) . ( G a not + z s tigma a point . ) Astigmatism is a term a p plied to an eye whose refraction i s n ot the

same in all its parts , causing the eye to focus

the light at di fferent points . It is subdivided

e a r re a r. into two kinds , r g ul and ir gul Irregular astigmatism is where there is a difference of

refraction in one a n d the same meridian , and

according to some authors , is subdivided into

n o rma l a n d a b no rma l . Normal irregular astig

3 4 L E I VI S P O CKE T

N o 2 S im e H e ro ic s ti . p l yp p A g ma tis m . d M 3 . c s t m No . Com p oun yo p i A i g a ti s m is that condition in which the two principal meridi a ns focus in front of the retina at differ ent places when the eye i s a t rest and looking

at infinity .

N o om i ti m a t is m . . 3 . C p oun d M y o p c As g

N 4 . S M c s t at s o . im pl e yo p i A i gm i m is that condition in which one of the principal merid ians focuses on the retina and the other in front with the eye at rest and looking at

infinity .

o 4 S im e M o ic As ti m a t is m . N . . pl y p g O PHTHALM IC DI C TIO NARY 3 5

M x ed s t ma t s m N o. 5 . i A i g i is that condition in which one of th e principal m eridians focuses in front of the retina and the other behind th e retina when the eye is at rest and looking at

infinity . It derives its nam e , mixed astigmatis m , from the fact that one meridian is hyperopic

' h r m i and the ot e yop c .

M ix e d s ti ma tis m N o. 5 . A g .

Corn ea l A s tigma ti s m i s cause d by irregularity t ‘ of h e curvature of the cornea . Lenti cul a r A s tigm a t i s m is caused by an irreg u l ri a ty of the curvature of the crystalline lens . A s tigm ati s m w ith t h e Rul e is where the axis of a minus cylinder that will correct the astig ma tis m is nearer the l 8oth m eridian than the

9oth , or the axis of a plus cylinder that will cor rect the astigmatism i s nearer 9 0 than 1 8 0;

otherwise , it i s against the rule . Correcting cases of high astigmatism often

p roves unsatisfactory at the time . When the i mage i s formed on the retina of such an eye it i s much blurred at one of the principal merid

ians , and sometimes distorted . H owever , the

patient accepts this , as his vision has never

been better . S o much so that when the correct

lenses form a distinct retinal image , he fails to

recognize it , and will sometimes say that the 3 6 L E W ]S PO C KE T

obj ect looks distorted , as the fibers of his optic

nerve are somewhat amblyopic , and therefore

diff erent from those of other people . In such cases the brai n i s in the habit of accepting vision from parts of the retina that are “ most

distinct , and when wearing their correction for

the first time , the vision shows very little im

provement , if any . It is not uncommon for

cases of say 4 -D of astigmatism to see very little better with their glasses at the time of

fitting , but if they are worn persistently the

vision i s expected to improve in a few months .

’ A s t igmom et e r. An instrument for measuring

astigmatism .

’ of As tig momet ry. Th e study of measurement

astigmatism .

’ - - s trin ere z to As t ri n ge n t ( as trin j en t) . ( L . a g

contract . ) An agent that causes contraction

and arrests discharges .

’ s mmet r - - et-r A y y ( ah sim e) . (Gr . a not syn

w ith metron measure . ) When the eyes do

not correspond , or resemble each other in

appearance , they are said to lack symmetry .

’ F t x . . A a ia (Gr. a not taxis order ) ailure of

muscles to coordinate .

’ t m t - m P A o ( a o ) . ( hysic s ) An ultimate indi

visible particle of matter .

’ t - i n c c . R d A o i (aton ) ( Gr . atonia languor . ) elaxe

without normal tone or tension .

t r . Gr . A op hy ( . a not trope nourishment ) A

wasting away of a part from a lack of nutrition .

’ t r n e -r - A o p i ( at o pin ) . A poisonous alkaloid ex

- tracted from atropa belladonna , or deadly night O P H T H A L LI I C DI C TI O NARY $7

shade ; it temporarily paralyzes the sphincter iridis ( circular mus cl es of the iris ) and the

Ciliary muscles within the eye , consequently the pupil i s dilated and accommodation fully re

l ax ed , leaving the eye adjusted for its far point

of vision in a state of rest . F or this reason it t is known as a myd ri a i c and a cyclo p l egi c , and is used more than any other to suspend a ecom

mod ti a on and dilate the pupil . Atropine para l yzes the sphincter muscle of the iris and the

ciliary muscle , and hence results 1 n dilatation of

the pupil , and also an inability to see clearly

near by . The dilatation of the pupil is a maxi I f mum one . , in the case of a d ilatation of the

’

pupil caused by oculomotor paralysis , atropine

is instilled , the pupil becom es still more dilated .

Thi s proves that atropine , b esides producing

paralysi s of the contracting fibers , causes al so

stimulation of the dilating fibers . The effect of th e atropine makes its appearance in from ten

to fifteen m inutes after the instillation , and

soon reaches its maximum . Commencing with

th e e a b ut third day it begins to decreas gain , does not disappear completely until after the

lapse of a week . The instillation of atropine ,

therefore , causes the patient a disturbance of

rather long duration , and hence should b e em

ployed only when there i s good reason for it .

’ -r - - At ro p i n is m ( at o pin ism ) . A condition produced

by the use of atropine .

’ z th e At ro pi n i e. To put under influence of

atropine .

' - - k Atyp i c H yp e rmet ro p i a ( at ip i ) . Irregular H yper

metrop ia caused by tumors behind the eye , ex erting such a pressure on the posterior pole 3 8 LE W I S P O C KE T

that the region of the macula is pushed in front

of the principal focus , the eye thus becoming

hyperopic . It may be caused by detachment of

the retina in the region of th e macula .

' t M -i -ik P M c a a t . A y p i yo p i ( p ) rogressive yopia ,

caused by the elongation of the eye .

’ t t a - - - - k Au o p h h lmo s cop e ( au tof thal mo s op e) . An ophthalmoscope planned in such a way that a

person can examine his own eyes .

’ v r v - - E e A e a ge ( a e raj ) . tymology obscure . The r sult of adding several quantities and dividing

the sum by the number of quantities .

’ - - Avoi rdup ois ( av or du ( F r. aver goods

2 de of pois weight . ) A system of weight

in which 1 1b . 1 6 oz . approximately

troy grains . f a . O e . Axi l , or p rtaining to , an axis

A x i a l Am et ro p i a . Ametropia that is caused by

the length of the eyeball on the op tic axis .

Axi ally. In the direction of the axis .

’ - - = Axiom ( ak si cm) . (Gr. ax ioma a requisite , a

- self evident principle . ) A simple statement , of

a general nature , so obvious that its truth may

be taken for granted .

’ s - i Axi ( aks s ) . A straight line , real or imaginary ,

passing through the center of a body, on which

it may revolve . O t p i c A . An imaginary line through all cen

ters of the eye from before back ; that is , the

center of the cornea , through the nodal points

"

to the inner side of the macula lutea .

Vi s u a l A . A line from the macula lutea through the optical center of the eye to the

point on the obj ect looked at . O PHTHAL MI C DIC TIO NARY 3 9

Maj o r A . The longest diameter of the cornea

M r or lens . ino A the shortest . P rin c i p a l A . A line which passes through the optical center of a lens at right angl es to both

sides , it is the only ray of light to pass through

unrefracted . 0

S econda ry A . Any line crossing the principal

ax 1 s at the optical center . These rays are re

fracted , but emerge in th e same direction as

they entered .

Axi s of a C ylinde r. The only meridian of a

cylindrical lens without focusing power .

Axi s of Mi rro r. A line which strikes the cen ter of curvature at right angles to th e surface

is called its axis .

Axi s of Ref ra ct ion . The normal to the surface of a refracting m edium at the point of incidence

of a ray of light .

’ m t x - m - - Ax o e e r ( a o e ter ) . An instrument for the

determination of the axis and focus of spherical ,

- cylindrical or sphero cylindrical lenses .

’ - - B AGI LLA R LAY E R (bas il ar ) . The layer of

rods and cones of the retina .

' - Ba rom ete r. ( Gr . baros weight metron

measure . ) An instrument indicating the atmos

p h eric pressure .

Ba s a li s La mina , or membrane of Bruch . The membrane which separates the choroid from the

pigmentary l ayer of the retina .

B . as e . (L . bassus low ) ( a ) The line or surface forming that part of a figure on which it is sup 4 0 L E \ V I S PO C KE T

posed to stand . ( b ) The base of a system of

logarithms is the number which , raised to the

power indicated by the logarithm , gives the

number to which the logarithm belongs . ( c ) In

percentage , the number which is multiplied by

the rate to produce the percentage . The base

of a prism is its thickest part . B as e A p ex Line . A straight line drawn from the

thickest to the thinnest part of a prism .

Ba s e urv e . C The meridian of least refraction , on

th e toric side of a lens .

’ B . a s edow s Dis ea s e ( S ee exophthalmic goiter . )

’ Be e r s K nif e . A knife with a triangular blade for

corneal incision .

B i. ( L . bis twice . ) Is employed to signify two

things in one ; for instance , bifocal , biconcave ,

biconvex . B i c o n cav e. Concave on both sides .

x Bi c onve . Convex on both sides .

B i- ifo ca l ( b fo H aving a double focus . A t lens with two focal leng hs , having two parts , the upper for distance and th e lower for near

vision . They can be made up in five different

ways , namely :

- . 1 . O n e B No p i ec e if oca l .

2 S t r F k No . . p li o ra n lin B ifo ca l .

No . 3 . P erf ect ion B if o c a l .

4 . No . . C e m ent ed Bif o c a l

No . 5 . Inv i s i bl e B if o ca l .

4 2 L E I VI S PO CKE T

out of position , and if they are heated too much t hey will chip off very easily .

B c a r L . ino ul . ( bis twice , oculus eye . ) P er

\ ' b oth e taining to ey s . In vision it refers to th e ability of both eyes to see the same point of a n

object at the same time . To prove it exists a 5 ° prism placed base up or down over one eye

should make the obj ect looked at appear double .

B b ta e . ior i l Angl The same as the optic angle .

B r f ra ct v i e i e . Doubly refractive .

- Bi S e r ca . d s p h i l A lens with a sphere on both si e .

- B r . M l ea eye arginal blepharitis .

’ B - - - = l ennor rh ea ( blen or e ah ) . ( Gr. bl en n os mu = cus + rh oia a flow . ) E xcessive mucous d is

charge .

’ - - - - - e a ra de t bl ef a d en i . Gr Bl ph ni i s ( ar tis ) ( . bleph f aron eyelid aden gland itis . ) In lam

mation of the meibomian glands .

’ - - = Gr. Bl ep h a ra l ( bl ef ar al ) . ( blepharon eyelid . )

P ertaining to the eyelids .

’ B - - l - - l ep h a relo s i s ( bl ef ar e o sis ) . Ingrowing eye

lashes . ( S e e Trichiasis . )

’ l f - - in Bl eph a ri s m (b e ar ism ) . Where there i s an ability on the part ofi h e patient to refrain from

winking . ( B linking )

’ — - i - Gr bl e h ron z e e Bl ep h a rit i s ( bl ef ar tis ) . ( . p y of th e lid itis inflammation . ) Inflammation

r or a r a s b. eyelids . C ili a i s m gin li That condi tion where the hair follicles of the e yelid are

S s a b . t s inflamed . q ua mo A marginal blephari i

in which the e dges of the lids become scaly .

U n c e ros a b . An ulcerous form of marginal

blepharitis . O PHTHALM IC DI C TI O NARY

’ ’ - - - - - B h b l ef o k a l . l e p ha ro c a l a s i s ( ar as is ) ( Gr . bleph

aron eyelid ch al a s is a slackening . ) R e

laxation of the skin of the eyelid , due to atrophy

of the intercellular ti ssue . A condition in which

folds of the skin hang down .

B - - k - - e a r n s bl f . l p h o clo u ( e ar o lo nus ) ( Gr . bleph

k n aron eyelid lo os a tumult . ) C l o n i c

spasm of the eyelids . B l e ph a ro co n j un ct iviti s . I nflammation of the eye

lids and conjunctiva .

’ B e a r n c bl f - - - l p h o us ( e ar ong kus ) . (Gr . blepharon

eyelid onkos a tumor . ) A tumor or swell

ing of the eyelid .

’ B e r — - - - — l p h a o pl egi a (bl ef ar o ple ge ia) . ( Gr . bleph l aron eyelid p eg e stroke . ) That state in

which the eyelid is paralyzed , causing ptosis .

’ B l f— - - - e r t s s b e . l p ha o p o i ( ar op to sis ) . ( Gr blepharon

eyelid ptosis a falling . ) That condition

where the upper eyelid droops from paralysis . B l ep ha ro pyo rrh ea . ( Gr . blepharon eyelid

pyon pus rh oia I flow . ) A discharge of

mucus from the eyelids .

’ B e a r rr bl f— - r l p h o ha p hy ( e ar or ( G . bleph

aron eyelid rhaphe seam . ) The stitch ing together of a part of the edges of a slit

between the eyelids .

’ B e a r - - - l p h o s p a s m ( bl ef ar o spasm ) . A spasmodic contrac tion of the orbicularis palpebrarum mus t cle , so that the lids are firmly press ed agains

the globe . O ccurs where photophobia is marked .

It i s reflex from the irritation of the fifth nerve , and occurs in neuralgia of its branches ; in inflammation of the conjunctiva or cornea ; from

foreign bodies ; errors of refraction , etc . 4 4 L E \ V I S PO C KE T

’ B - - - f . r l e p ha ro s ta t ( bl e ar o stat ) ( G . blepharon

2 eyelid statos fixed . ) An instrument used

for holding the eyelids apart .

’ B e a r t e n s bl e f e ar t l ph o s o i s ( o s e no sis ) . Gr .

blepharon eyelid stenosis a narrow ing . ) A narrowing of the palpebral slit between th e

eyelids .

' ------B r e l f k i . l eph a o s y n chi a ( b e ar o sin e a ) . ( Gr bleph

aron eyelid synechia continuity . ) A con dition in which there is a growing together of

the eyelids .

’ - - - - l . e Bl e ph a rotomy ( b ef ar ot o me ) . ( Gr . bl pharon

eyelid tome incision . ) A surgical opera

tion for the c utting of the eyelid .

- B . li n d L oss of sight . Day blindnes s i s where

- vision i s better at night . Night blindness is de

- fective vision at night time .

B . lin d S p ot Also known as the optic di sc , or h e optic papilla . It marks the entrance of t

t . optic nerve on the retina . Not sensitive o light

Blink ing . That condition in which there is an

involuntary winking .

B d bl ud . loo ( ) A red . slightly translucent fluid which circulates in the p rincipal vascular s ys

tem of animals , carrying nourishment to all n parts of the body . and bringi g away wa ste

products to be excreted . In the veins its color

i s somewhat darker , owing to the loss of oxygen

while passing through the tissues .

B d V e s e S loo s l s . ( ee veins and arteries . )

' ’ e B t s a s e . onn C p ul The same as Tenon s Capsule .

’ Bow ma n s Me mb ra n e . The second anterior l a yer

of the cornea . O PHTHALM I C DI C TI O NARY 4 5

’ B ra c h met r a - e— - - e- Gr y o p i ( brach me tro p a ) . ( . brach t us short , m e ron measure , ops eye . ) The

same as myopia and hypometropia . It is an eye where parallel rays of light will focus in “ front of the retina with the muscles of a ecom

moda tion at rest . B T ra i n . h e organ of intellect . A nervous mass

wi thin the skull divided into many parts .

B - - row Agu e . S upra orbital neuralgia ; a superficial ‘ pain in the region of distribution of the firs t

division of the fifth nerve .

’ - B ruch s Gl a n ds . The lymph follicle s of the con f juctiva o the lower eyelid .

’ B ruch s M e mb ra n e . The inner layer of th e choroid

coat of the eye . ’ i B ruc h s Mu s cle . ( S ee Cil ary Muscle . )

’ - - - B h . up th a lmi a ( buf thal me ah) . (Gr bous ox

2 : E . op h th al mos eye . ) nlargement of the eye

S e e B . Bup hth a l mus . ( uphthalmia )

' M - — - CA M P I ET E R ( kam pim e ter ) . ( L . campus

field Gr . metron measure . ) An instrumen t

v f or measuring the field of vision , replaced b

perimeter .

C a n a da Ba lsa m . A liquid resin obtained from the

- fi I is balsam r tree . which grows in Canada . t used for the purpose of cementing lenses to

r d il v gether . It i s easily m elted if heated . and ea

soluble in alcohol . ( S ee bifocal for its us e . ) Index of refraction

’ C a na li c ulu s . A small canal or channel . 4 6 LE W I S P O C KE T

’ n C a a l of Cloq u et . The name given to S tilling s

Canal after Jules Germain Cloquet, P arisian

- surgeon , 1 790 1 8 83 .

C a na l of P etit . The space which surrounds the crystalline lens between the suspensory liga

ments .

C a n a l of S chl emm. Circular canal surrounding th e eye at sclerocorneal junction . ( S ee

Anatomy . )

C a na l of S tilli n g. Th e canal which runs through the vitreous humor from the entrance of the

optic nerve to the posterior surface of the lens . I t is lined by the hyaloid membrane . This canal is said to convey the minute artery from th e central artery of th e retina to the back of

th e lens , during development of the eye . The

artery then disappears , but the canal remains .

It is also known as the H yaloid Canal .

C a nal s of Fo n ta n a . A number of little spaces or

openings between the iris and cornea , in the

sclerotic . ( S ee S paces of F ontana ; also see

’ S chlemm s Canal . )

’ - = n e . L O C a c l (kan sel ) ( . cancelli a lattic e . ) rig

in all y to draw lines across a calculation . To strike out or eliminate as a common factor in the term s of a fra ction / a common term in the

tw o of . members . an equation , etc

’ a t ect m k n - h k k n th s C n h o y ( a t e (Gr . a o , k canthus e tome excision . ) An operation in w hich part of the canthus i s cut away .

’ C a n thitis kan -thi - i ( t s ) . Inflammation of the angles

of the eyelids .

C t - — a h s is . . k an thos n oly (Gr , canthus l lysis O PHTHALM IC DI C TIO NARY 4 T

loosening . ) Incision of the canthus to widen the

slit between the lids .

’ - - - C a n tho pl a s ty (kan tho plas te ) . A surgical opera tion for lessening the pressure and friction of

the upper li d by cutting the outer canthus .

P l a s t i c c . operation , an operation for restoring a

lost part .

’ - - - An C a n thotomy (kan thot o me ) . operation for

the slitting of either canthus .

' n Ca th us . ( Gr . angle of the eye . The angle

. at the jun ction of the eyelids , known as the

inner and outer canthi .

’ n C a p ill a ry (hair like) . Any o e of th e little ves sels which conduct the blood from the arteries

to the veins .

’ - = l x . a s u e . ca su a a bo C p l (kap sule ) (L . p ) A sac which encloses a n * organ for the purpose of

support , protection and lubrication . The cap

sule of the eye lens .

’

a s e of T e n . S ee e C p ul no ( Ten n s Capsule . )

’ - - - C a p s uliti s ( kap su li tis ) . Inflammation of the

cap sule of the Crystalline lens .

’ t - - - - for C a p s ulo omy ( kap s u lot o my ) . An operation

. the cutting of a capsule , as, that of the lens

C a rdina l P oints ( that on which a thing turns or P depends ) . oints which play an important part in the course of light through a spherical sur

face . There are four in number . The two prin i t c p al foci and th e two nodal points . Th e firs principal focus i s the point f rom which light rays emanate and pass through a spherical lens

and emerge parallel to its principal axis . The second principal focus is the point where th e 4 S LE \ V I S P O C KE T

emergent rays cross each other when the inci dent rays have been parall el to th e principa l

S e axis . ( e Nodal P oint . )

’ a r t d ka- - id C o i ( rot ) . ( Gr . karos deep sleep . s tupor ; so named from th e e ffect of pressing

0 11 them . ) The carotid arteries or carotids are

th e of t n v two great arteries the neck , hat co e v

th e th e a n d blood from the aorta to head . brain Th . e t t eye common caro ids . one on ei her side

of the neck , divide in to an external and an

internal branch , the former supplying the ex

r r te io of the skull .

’ a t - - i = a a . L Ca rt l ris tl . C r il ge (kar til j) ( . ago g e ) T h e gristle or white elastic substance in di ffer

ent parts of the body . ( S ee Tarsus . )

’ - - -ih - R C a rtila ginous ( kar til aj us ) . elating to or

consisting of cartilage .

’ r L h r m lis - n -k u C a unc ula a c y a (kar u ( L . a

L t . small fl eshy mass . . lacrima a ear ) Is the

small reddish body at the . inner canthus of th e

eye .

C as t . A cast in th e eye would apply to strabi smus .

’ t r - a -f -r - Gr a a a o e . . C pho i ( kat ah ) ( kata down . ” phoria tendin g ) Tha t condi tion in which it w one of the eyes , though parallel with s fello

extrin when in use , turns downward when the

E t r s ic muscles are in a state of rest . s o ca a p ho i a is the tendency of the visual line inward and

E t th e d ownward . xo c a a p hori a i s a tendency of

visual line outward and downward .

’ t t - - C a a ra c ( kat ar akt ) . ( Gr. kataraktes to b reak

down . ) Any opacity of the crystalline lens or

L t r c . lens capsule of the eye . e n i c ul a , an

e a s a r c . opacity of the l ens prop r . C p ul , an

5 0 LE W I S P O C KE T

dle . The first will b e on the surface of the

cornea in an upright position , the second will

be on the anterior surface of the lens , also up r right , while the third will be inve ted and much

smaller on the posterior surface of the lens , but when there is a cataract you will fail to find th e

inverted image ( known as P yrk in ges Images ) .

’ Cato t r - - Th p y (kat op tre ) . e unit of reflective

‘

power of curved mirrors . A mirror that will reflect parallel rays of light to a point of focus

at a distance of one meter .

’ t - P C a s eye up il . Where th e pupil of th e eye is

- long and narrow ( slit like ) .

’ - C a us ti c C urve (kaus tik) . A curve to wh ich the

° rays of light reflected or refracted by another

curve are tangent .

C a us ti c S urf a c e . A surfa c e to which rays of light reflected or refracted by another surface are

tangents . Caustic curves are called catacaustic when formed by reflection and diacaustic when

formed by refraction .

’ t - - - th C ell uli is ( sel u li tis ) . Inflammation of e loose

tissues of the orbit .

C en te r ( of curvature ) . If the surface of a lens

were completed so as to form a circle , its center

would be the center of cu rvature . ( S ee O ptical

Center . )

’ - - — - C e n timeter ( s en tim e ter) . O n e hundredth part

of a meter .

' - C ent ra d ( sen trad) . Toward the center ; unit of measurement for prisms which will produce a deviation in a ray of light one-hundredth of a

radian . O PHTHALM IC DI C TI O NARY 5 1

’ t - c e n ri c ( sen trik ) . P ertaining to a nerve center .

’ C e n t rif l - - - i u a u . g ( sen trif gal ) Tending , or caus ng ,

to recede from the center .

e t r f m C n i u ga l I p res s ion . An impression sent from a nerve center outwards to a mus cle or muscles

by which motion is produced .

e t r s e . .k en tron C n o pho (Gr . center phos

light . ) A subjective sensation of a light spot or n patch , the cause being located in the optic brai

center .

’ - - - e ra t t s at i . s uflix C i i ( ser tis ) (Gr . horn + , itis m inflam ation.) The sam e as keratitis .

’ C e r t - - - - a o n os us ( ser at oh o sus ) . ( Gr . keras Any disease of the

cornea .

’ — - - C e ra totome ( s e rat o tom ) . A knife for dividing

the . cornea .

’ a az - -zi- u Ch l ion ( chal a o ) . ( Gr . A tumor r on the eyelid . O n the under su face of the tars al p l ate of the upper and lower lid are

’ numerous creases or depressions running at

right angles to the margin of th e lid . There

‘ ‘ are about thirty of th em in the upper lid and about twenty in the lower? In these d ep res

sions are small tubular glands , called meibomian

glands , and their ducts open next to the margi n az of the lid . A chal ion is an enlargem ent of

one or more of these glands , due to the stop page of their ducts and is usually chronic in ,z character . A chala ion i s also called a tarsal t umor , tarsal cyst , or meibomian cyst , etc . It is

not a true retention cyst , but its contents may soften so that it will become an encysted

absces s . At first its contents are gelatinous , 5 2 LE W I S P O C KE T

“ but later may become purulent . The tumor i s

firm , round , with the skin moving freely over

the mass , but it is firmly attached to the tarsal

plate . It has so much the appearance of a seba c eous cyst t hat one is liable to be mistaken in

‘ the dia g n os is f n n l es s he is familiar w ith the ' z disease . , U sually chala ion tends toward the

' conjunctiva , and , if th e lid is everted , the posi tion of the tumor may be located by a bluish t discoloration , or , if the contents are purulen ,

a yellowish discoloration . The primary cause

of this trouble is not definitely known , but a

- debilitated condition of the system , eye strain , and blepharitis marginalis seem to be the fac

tors in producing chalazion . m h m. C a be r. ( Gr . vaulted roo ) The spaces of O

the eye . A term used in speaking of the eye ,

- n in which there are three chambers. The a

t e rior c . i s the space between the cornea and “

h . t e front surface of the iris ; the p o s t e rio r c , the space between the iris and the front sur l face of the ens capsule . These two are filled with the aqueous humor and communicates

through th e pupil ; v it reou s c . , the space sur rounded by the hyaloid membrane behind th e

-fi f th e lens , occupying four th s of the globe of

eye .

’ k - - C h e mo s i s ( e mo sis ) . ( Gr . an aperture and

suffix osis , s ignifying morbid condition . A

swollen condition of th e conjunctiva , forming

an elevated ring around the cornea .

’ - h i m = two Chia s m (k i asm ) . ( Gr . c a s a crossing of lines . ) A crossing ; especially the crossing

the fibers of the optic nerve ( optic commi ssure ) . O PHTHALM I C DI C TI O NARY 5 3

’ h a s to met e r k i- - - - C i ( as tom e ter ) . An instrument t for ascertaining the devia ion of the optic axis .

’ h r ha n e -ro- C lo o p (klo fan ) . ( Gr. chl oros green

' h i z l - ish yellow p a n o show ) . A green yellow

pigment from the retina .

h l r h l r C o o p s ia . ( Gr . c o os yellowish green o s is = i h p eyes g t ) . Green vision . A condition

in which all obj ects appear to be colored green .

k ’ Cho ed Dis c . Congested and inflamed state of

the optic disc .

’ d - h n r Ch on ra l (kon dral ) . ( Gr . c o d os cartilage . ) P ertaining to cartilage .

’ r k - r - r h r Cho ea ( o e ah ) . ( G . c o eia choral dance . )

’ S t . Vitus dancez. A disea se of the nervous sys tem , characteri ed by a succession of irregular ,

clonic involuntary movements , of limited range

occurring in almost all parts of the body . Con

trol of the muscles is not lost , but voluntary

” motions are interfered with by the involuntary

contractions .

r e Cho ioi d . S e Choroid .

’ ' C k - - k ho roid ( o roid ) . Skin li e bag with multitude

of blood vessels . That part of the second tunic of the eye extending from the optic nerve eu

trance to the posterior limit of the ciliary body .

It is covered by the retina on the inner side .

It constitutes the posterior two - thirds of thi s

Vascular tunic . Its thickness gradually dimin

ishes toward the ciliary body . The choroi d

consists of a compact mass of connective tissue ,

stroma , which supports the numerous blood

vessels of varying size ; forming three layers . 5 4 LE W I S PO CKE T

1 . The layer of stroma containing large blood

vessels .

2 - . The chorio capillaris .

3 . The membrana vitrea .

The first layer i s the most conspicuous of th e

three , for its large blood vessels emerge into

four main trunks , the vena vorticosae ; these

pierce the sclerotic at equal d istances apart ,

running obliquely backward . The nerves of the choroid are derived from branches of the long

and short ciliary nerves . Its blood supply i s

from the short posterior , long posterior and n a terior ciliary arteries . The red reflex seen i n the eye when viewed with the retin o s cope and ophthalmoscope is due to the reddish color of the blood vessels in the choroid showing

through the retina .

Cho roida l Fi s s u re . The opening in the choroid through which the optic nerve passes to form

th e retina .

’ - - - - - Cho roid e remi a ( k o roi de re me ah ) . Absence of

the choroid .

k - - di - C ho roi diti s ( o roi tis ) . Inflammation of the

choroid .

’ ' Cho roido cy cli tis . Inflammation of the choroid

and ciliary processes .

’ - - - - - Cho roidoiriti s (k o roi do i ri tis ) . Inflammation of

th e choroid and iris .

’ Cho roi do retini tis . Inflammation of the choroid

and retina .

’ - - = Ch rom a ti c (kro mat ik ) . (Gr . chroma color . )

R elating to color .

C h romati c A b e rra tion . S ee Aberration . O PHTHALM IC DI C TIO NARY 5 5

’ m t - - o- - - - r a d s a o . Gr Ch o o y o p i ( kro mat dys pi ah ) ( .

2 chroma color dys bad ops eye . ) Col

- or blindness .

’ Ch r a t e us - - - n - om o g no (kro mat oj e us ) . ( Gr . chroma

2 en n a o P . color g z I produce . ) roducing color

’ C r at l - - ol - o- h om o o gy ( kro mat gy ) . The study of

color s.

’ Ch romatom et e r. An instrument for measuring

color or color perception .

’ r at - - - f - - Ch om o pho bi a (kro mat o o b e ah ) . (Gr. ch ro

2 ma color phobos fear . ) An abnormal

fear of color .

’ ma t s - - - r a o s e . Ch o o p i (kro mat p ah ) (Gr . chroma i color op s s vision . ) Abnormal sensation

of color , due to disorders of the optic centers , t o . or drugs , especially santonin

’ r at t met r - - - - t-r Ch om o p o y (kro mat op tom e y ) . Tak ing the measurement of the power of color per

cep tion .

’ - - - Ch romomet er (kro mom et er) . An instrument for

measuring coloring matter present .

’ t - m - m - r in s tru Ch romo ptome e r (kro op to e t e ) . An

ment to test the color sense .

o s ko eo Ch romo s co p e . (Gr . chromo c lor p I

view . ) An apparatus for testing the color sense .

’ - - - in C ib is itome ( sib is it om) . An instrument for

cising the lens capsule . = m e el ash . . C ili a . ( L . ciliu y ) The eyelashes

H air .

’ - - - - Cilia ri s co p e ( sil i ar is cope ) . An instrument for

examining the ciliary region of the eye . 3 6 PO C K E T

’ a r -i- a - r P t to C ili y ( sil y ) . er aining , or like , the eye

lashes .

C ili a ry Body . The middle part of the second tunic ,

s composed of ciliary processes , ciliary vein ,

ciliary muscles , ciliary nerve s and arteries .

C u n r id i ia r od r is a n d N e r v e s . t s h ow i g C h o o . C l y B y . I

‘ C r s ili a y P ro c e s s es . The radiating circular fold

' v t s troma wh ich composed of a connecti e issue ,

s th t pas up over e ciliary body . There are abou

sixty or seventy in number .

’ C - r . illo ( cil lo ) or C illo s i s . (G I move . ) A

trembling or spasmodic twitch of the eyelids .

’ C - - r - i = in e rea ( sin e e ah ) . ( L . c n ereus a s h y . ) The f h t gray matter o t e nervous sys em .

’ - C r k . . i c l e ( sir l ) ( L . circulus , dim of circus . Gr

— kirkos a ring . ) A plane figure whose periphery

5 8 LE W I S PO C KE T

pupil by cocaine is not produced , as in their

its case , by action upon the contracting or th e

dilating fibers of the iris , but by a contraction of

‘ v l the bl ood es s e s of the iris . The dilatation of th e l pupi i s therefore only a moderate one , and th e

v reaction of the pupil to light persists ; moreo er ,

mydriatics and miotics still produce - a n effect . If cocaine is instilled into an eye the pupil of t which has been dilated by atropine , the dila a tion in crea s es e omew h a t in consequence of the anaemia of the iris which then ensues ; hence the mydriasis produced by the simultaneous action of atropine and cocaine is the most com

p l ete that can possibly b e attained . The a o

n - commodatio i s not paralyzed by cocaine , but

only somewhat weakened .

’ k -h - L z Coh es io n ( o e shun ) . ( . con tog eth er +

v h a ereo to stick . ) That form of attraction b which the particles of a body are united

throughout the mass , whether like or unlike .

’ - - C olma s c op e ( col ma scope ) . An instrument for

the detection of strains and stresses in lenses ,

either mounted or unmounted , as a result of undue tightening of screws or imperfections in

manufacture .

’ r -l r - i- k oll rion Colly i um ( col y um ) . ( Gr . y an

eyewater . ) Any lotion to b e dropped in the eye .

‘ ’ - - - k o . l ob ma a C lo bom a (kol o bo mah ) (Gr . o o n

imperfection . ) A tear or break in the eyeball ,

as in the iris or choroid .

- Colo r Bli n d n es s (Achromatopsia ) . B lindness for

one or more colors . Due to the absence from the retina of one or two of the three primary substances ( according to H ering ) . The test is O P H TH A LhI I C DI C TIO NARY 5 9

made by presenting the patient with samples of e — differ nt colored yarns a number of each color , but different shades — and the patient is re

quested to separate them . P ersons having this anomaly of vision are generally unaware of it

themselves .

’ mm s - - r C o i s ure (kom mis u ) . ( O ptic ) (L . com “ ” x - mittere , to unit e ) The like crossing of the

optic nerves .

’ m t b e r - - i = s e t . L c m C o p o i Num (kom poz ) ( . o to

gether ponere to put . ) A number which can b e exactly divided by a number exceeding

unity .

Com p o und Len s . A lens that contains a sphere

and a. cylinder .

’ - Comu s ( k o mus ) . A cone . A crescentic patch of atrophic choroid tissue near the optic papilla in

myopia .

: ca v . L n l C on e ( . co cavus h o low . ) H ollow and

curved or rounded . The opposite to convex .

' - C on cavo conv ex . Concave on on e s ide and convex

on the other . If the convexity exceeds the con ‘

cavity it is known as a peri scopic convex lens . If the concavity exceeds the convexity it is

known as a periscopic con cave lens .

’ - - Con c ent ri c (kon sen tric ) . ( L . con together

centrum center . ) That which has a common

mth in . center with . s o e g else

- C on c entri ca l (tri kal ) . H aving a common center ,

as circles of different size , one within another .

’ - - - n mita re it L . co co C on com ita nt ( kon com ant ) . (

n c ta t to accompany . ) Accompanying . Co omi n S q uint is a condition where the two eyes devi 6 0 LE W I S PO C KE T

t v ate , but accompany one another in heir mo e t ment . The obj ect can be seen by ei her eye ,

but not the two eyes at the same time .

C o n e ( Gr. konos peg . ) The elementary form considered in arithmeti c is a solid gen

erated by the revolution of a right - angled tri

angle about one of its sides as an axis .

Co n e Mu s c l e T es t . This consists of a cone

s cemented to a ground glass disc , and i s used a follows : It i s inserted into one cell of trial frame in front of th e correction for the a metro

pia , which must be properly centered as to

pupillary distance , and a solid blank disc i s p ut n i to the cell in front of the other eye . The patient ’ s attention is then directed to a light ( preferably a candle or small gas light ) tw enty feet away ; and the action of the cone i s such that the light will resolve itself into a circle of if l ight . The other eye is then uncovered , and there is no muscular error the light will appear

in the center of the circle . If there is muscular error the light will be either above or below or

t to to one si de of center , and can b e brough . center by the proper prism with base i n proper

position . This does away with necessity for computations where there is combined prismatic

fi n th e error in di ere t angles , and gives at once

position of the base of the correcting pri sm .

( S ee Muscular Imbalance . )

’ - - l c Coni cal ( con ic a ) . That whi h is round and

t apering to a point .

C - th e oni ca l Co rn ea . A cone like protrusion of cornea anteriorly due to increased intraocular

pressure and weakening of its cen tral portion . O PHTHALM IC DI C TIO NARY 6 1

M any form s of operations have been suggested

and while some have been of slight b enefit , no

complete cure is known . Vision can usually be improved by means of an opaque disc with a n

opening in its center and worn as an eye glass .

( S am e as K eratoconus . )

L 2 n u a t e . u a re . Co j g ( . con with j g to join )

Coupled . To yoke together .

C n o j ugat e D ev i a tio n . The deviation of both eyes

in the same direction .

’ C o n j uga t e F oc i (kon - ju Two points s o situ ated in relation to each other that the direction

of a ray proceedi n g from either of them , after

reflection or refraction , passes through the

S d r c . other . econ a y A conjugate foci formed

on a secondary axis .

’ n un t v - - - = ith Co j c i a (kon junc ti va ) . ( L . con w +

un j g ere to join together . ) The mucous mem

brane of the eye . It covers the anterior sur f face o the eye , passing backward about one

half inch , where it turns ( fornix ) to line the

inner surface of the eyeli ds , thus forming a I complete sac when the eyelids are closed . t

' consists of two portions the ocular portion ,

which covers the sclerot ic , and the palpebral

portion , which lines the inner surface of the t d lids . The ocular portion is loosely connec e

wi th the sclerotic , but firmly attached to the

edge ( limbus ) of the cornea . The palpebra l

portion i s thick , opaque , highly vascular , and m covered with numerous papillae . At the argin

of the lids , it becomes continuous with the lin ing membrane of the ducts of the meibom ian

glands . At its outer and upper angle there are LE W IS PO CKE T

from seven to ten ducts through which the tears

pass from the lacrimal glands . It receives its blood supply from the palpebral and lacrimal

- u to arteries . Its vein , the post tarsal , is trib tary

the ophthalmic vein . It receives its nerve sup ply from the fifth pair entering at the inner and

outer angle of the orbit .

’ - - - i - Conj un cti v iti s (kon junc tiv tis ) . Inflammation

of the conj unctiva .

’ - - = i h v L . n w t Con e rgenc e (kon ver gence ) . ( co +

‘ = i' ve rg ere to turn . ) The act or powe of turn

ing the eyes from their position of rest . When the eyes are emmetropic and ortho

h ri p o c, th e two functions , accommodation and

convergence , work together , yet their objects

- are totally different , but their harmoniou s co t opera ion is none the less essential . The func t ion of accommodation i s the focusing of the

rays of light , on the retina of each eye singly , which come from obj ects looked at within 2 0 feet from the eye ; while the function of con vergence is the turning of the eye so that the image of the obj ect looked at will fall on corre

‘ n s p o din g parts of th e retin a in each eye . F or a pair of normal eyes to view an obj ect at a given distanc e th e sa me amount of accommodation

n and convergence will be required . F or i

stance , to View an object at 1 3 inches , it will be

' necessary to use three dioptries of a ccommo

dation and three meter angles of convergence ,

and if the obj ect was brought nearer , the a ecom modation and convergence would increase an

equal amount . The same nerve (third or moto r oculi ) suppl ies the muscles that perform both

functions . Turning the eyes outward from their O PHTHALM IC DI C TIO NARY 63

n t position of rest is called ega ive co n v e rgenc e , or abduction ; turning the eyes inward from their position of rest is called p o s iti v e c o n v e rg

n e ce , or adduction . The number of degrees of convergence that can b e used without changing the accommodation is called rel ativ e c o n v e rg

e n ce . i m t . The total amount one has , the A p li ude

“ o ve r e . n g Directed toward the sam e point .

' " on v ex . That which has a rounded and elevated

surface . The surface , if continued at the same

radius of curvature , would form a complete

circle , or sphere .

- on v exo con cav e. Convex on one side and con

cave on the other . If the convexity exceeds the concavity it is known as a periscopic convex

lens . If the concavity exceeds the convexity it

is known as a periscop ic concave lens .

’ - - - - = o io i i o . k o s fa ti p p a (kop pi ah ) . ( Gr p o gue +

o - ps eye . ) A worn out state of the eye caused

- by eye strain .

P n L l a o e n s es ( plus 8D . on one side and M i i l minus 8D . on the other ) . Coq u l e are plus

4D . on one side and minus 4D . on the other .

They are nearly always colored .

’ - k - - k z lis is ( kor e lis is) . (Gr . ore p up il

sis closure . ) That condition in which the

p il of the eye is obliterated .

' - - - k . ctas is (kor e tas is ) Dilatation of the pupil .

’ - - - ctome (kor ec to me ) . An instrument used in

cutting for iridectomy .

' t m k - - - k : orec o y ( o rek to me) . ( Gr . ore pupil

ektome excision . ) S ee Iridectomy .

' - - - - o . G p i a ( kor ec to pi ah ) . ( r. kore pupil 6 4 LE W I S PO C K E T

ek t op os out of place . ) That condit ion in

which the pupil i s displaced .

' red a s - - - - - Co i ly i s (kor e di a l y s is ) . An operation in which the iris i s detached from the ciliary liga m ent for a new pupil .

' k - - - re s s o . Co ly i ( rel is is ) (Gr . kore pupil lysi s

a loosening . ) The loosening of adhesions b e w t een the capsule of the lens and the iris .

' re m r s s - e- - - Co o p ho i (kor mor pho sis ) . ( Gr . kore

2 pupil morphosi s formation . ) Creation of an

artificial pupil .

’ t - - - - re e r m et er . r Co om e ( kor e o ) ( G . kore pupil

metron measure . ) A contrivance used for

m easuring the pupil .

re t Gr a s . C o pl y ( kore pupil p l a s s o I form ) .

An operation for forming an artificial pupil .

’ - - r e n . L n Co n a (kor e ah ) ( . cor eus

The anterior one - sixth of the first tunic of the t eyeball . It is transparent , convex , and fi ted

into the sclerotic like a watch crystal , having a

radius of mm . on its anterior surface and

mm . on the posterior surface . It has a vertical zt diameter of about 1 1 mm . and the hori on al

diameter is 1 2 mm . In thickness it is about 1

mm . at the center , while at the periphery it is

- mm . The cornea has no blood vessels ex t cept for a narrow space about 1 mm . wide a

the margin , derived from the anterior ciliary

arteries . The venous roots become tributaries

of the anterior ciliary vein . The cornea is well

supplied with nerves and lymphatics . It serves to

transmit light into the eye , and next to the layer It of tears becomes the first refracting medium .

I s . curv is convex in front and concave beh ind . t

6 6 LE \ V I S PO C KE T

r Co n eo s cl e ra . Th e corn ea and sclera taken to

gether, forming the external coating of th e

eyeball .

’ ’ rra d at - ra - - - Co i ion ( kor di a shun ) . A conjunction or

concentration of rays in one point .

rr ct . M Co e ion aking good an abnormal condi tion ,

such as correcting an error of refraction .

’ t - - Z r c l . a a . L ort X k Co i l (kor tik ) ( c e b a r . ) To b e

near the border . Co rt i c a l C a ta ra ct is that vari ety in which the opacity begins at the border of the crystalline lens and gradually spreads

toward the center , which it sooner or later

involves .

’ t k - - Co s eca n ( o se kant ) . The secant of the comple

ment of an arc or angle .

’ k - Co s i n e ( o sin ) . The sine of the complement of

an arc or angle .

’ ' - - n Cota nge nt (k otan j ent ) . The ta n g e t of the com r pl ement of an a e or angle .

Cou ching . That condition in wh ich the lens is i n displaced in cataract . Th is op era t o is now

obsolete .

’ - Cov e rs ed S in e (k o verst sine ) . The versed sine

r of the complement of an a e or angle .

Cove r T es t . A test for muscular imbalance by covering one eye and observing its movement

while uncovering , the point of fixation being

established .

C ra m p . A spasmodic muscular contraction .

’ - - L . C ri b riform (krib ri form ) . ( cribrum sieve

2 P . forma form . ) erforated like a sieve

’ - - in C rit i cal Angl e ( krit ik a l ) . The least angle of c id en ce at which a ray of light traveling in a O PHTHALM IC DIC TIO NARY 6 7

denser medium is totally reflected at the sur face which separates it from a rarer med ium ;

also known as limit angle . The limit angle of

° ° crown glass is 4 0 that of flint glass , 3 7

r s s d D C o e i p lo p i a . S ee Diplopia .

s ta r i Cry llin e ( G . e y s tal Clear , transparent . R f' esembling or of the nature c crystal .

C rys ta lline Le ns ( krys T he lens of the " eye , which resembles a cry s ta l . I t is a b i

convexed , transparent , e lastic body having a

8 . diameter of about . 5 mm and its axial thick u ness about mm . It has a radi s of curvature

on the anterior surface of 1 0 mIn . , and that of

S . h e the posterior urface 6 m m , while t eye is in

a. state of rest . It is located in the hyaloi d fossa th t of e vitreous , j us b ehind the pupil , and i s

made up of layers like an onion , which gives it

an elastic nature . The lens itself is enclosed in

the lens capsule , which is held in position by

the suspensory ligaments . Its index of refra c tio n is and it represents from 1 6 to 1 9 diop

tries of plus when the eye i s at rest .

m r rto ete . C rytomete r. S ee Cu = k . Cu b e (kub ) . (Gr. ub os a die , a cube ) (a ) A regular solid with s ix square faces ; ( b ) to raise to the third power ; ( 0 ) the third power of a

number .

Cu be Root . The cube root of a perfect third power

is one of the three equal factors of that power . A number which has not a perfect third power

has not three equal factors .

’ - - - u e s n e us L . . C n u ( cu ) . ( wedge ) The wedge shaped

portion of the occipital lobe of the cerebrum , si tuated between the occipital and calcarine 6 8 LE \ V I S P O CKE T

= fissures . The cuneus receives the cortical ter

mini of the optic tract .

C e D i upp d s c .

u D C p p e d i s c . Tha t condi t ion in which the optic

disc has becom e cupped , as seen in glaucoma .

’ Cu rt om et e r. An instrum ent for measuring curved

surfaces .

’ rva t ur rv - - Cu e ( cu a ture ) . The bending of a line

without form ing angles .

’ k - - - t n m . Cu a eo us ( u ta e us ) . P ertaining to the skin

’ - - k k Cy c l it i s ( cyc li tis ) . (Gr. y l os circle itis

inflammation . ) Inflammation of the ciliary

body .

’ - - - - - I ma Cy clo cho roiditi s ( s i xl o ko roid i tis ) . n fl am

tion of the choroid a n d ciliary body .

- Cy cloi d ( si kl oyd) . Like a circle .

’ - - - - k klos Cy c lo p ho ri a ( cyc lo fo ri ah ) . ( Gr . y circle O PHTHALM IC DIC TI O NARY 6 9

phora movement . ) That condition in which the vertical axis of the eye inclines to the right

or left instead of standing vertically , the ex trin

sic muscles being a t rest .

’ - - - = e . r k k Cyclo p i a ( si klo p ah ) ( G . y l os circl e

2 ops eye . ) A single eye in center of forehead .

’ - - - - k k z- c i . r l Cyclo p l egi a ( y clo ple g ah ) ( G . y os cir

cle p l eg e stroke . ) P aralysis of the ciliary

muscles .

Cy c lo pl egi c . A drug which produces paralysis of the ciliary muscles or muscles of accommoda tion

’ k kl o Cy clot omy ( Gr. y s circle tome inci

sion ) . O peration of cutting the ciliary body of

the eye .

k k l 2 r os . C yclot ro p i a ( G . y circle trope turn )

The actual turning of an eye on its optic ax 1 s .

’ - in - k n = Gr . li dr . Cylinde r ( cyl der ) . ( y os a roll ) L S ee ens .

R . Cylind ri ca l . elating to or the shape of a cylinder

Gr k i s t . s t s . Cy ( sist ) . ( y bladder ) Any sac con

taining a liquid . D ermoid cyst is congenital .

n n fl It is a painless , u i ammed spheroidal mass , situated generally at the outer angle of the

orbit , on a level with the outer end of the eye

brow .

’ t - - m C yst i om e ( sis tit o ) . An instrument used for

opening the sac of the crystalline lens .

’ s t t k s tis C y o omy ( Gr . y bladder tome inci

- sion ) . Incision of the capsule of the Crystalline L ens . 70 LE W I S P O CKE T

D . . Abbreviation for dioptry , dexter , or dose

’ Da c r a d e a a - r - a d- eu- al - i- ah Gr y n lgi ( dak y g ) . ( . dak a l ryon tear aden gland gos pain . ) P a in I n a lacrimal gland .

’ - - - = Da c r a u r . Gr y gog e ( dak y a g og ) ( . dakryon tear a = + gogos leader . ) A medicine which causes _

a flow of tears .

’ ------D r t n r. a c yoa deni is ( dak ry o a d e i tis ) . ( G dak I n fl mma ryon tear aden gland itis . ) a

tion of a lacrimal gland .

’ D - - - k r n z tea r a c r c e e r r. da o yo l ( dak y o cele ) . ( G y

kele hernia . ) A protrusion of the lacrimal

sac .

’ Da c r c s t -r - — r yo y ( dak y o cyst) . ( G . dakryon tear k s ti . y s sac ) The tear sac .

’ Da c r c s ta -r -o- - al - i- Gr yo y l gi a ( dak y cyst g ah ) . ( . dak

ryon tear k y s tis sac a lgos pain . ) P ain in the lacrimal s ac .

' D r t t -r — - - - a c yo cys i i s ( dak y o cys ti tis ) . Inflammation

of the lacrimal sac . D ’ a c ryoid. R esembling a tear .

’ - — - =- D r m r . r. a c yo a ( dak y o ma ) ( G dakryon tear ,

and suffix oma , morbid state . A lacrimal tumor which causes an obstruction of the lac

rimal puncta , so that the tears flow over the

lids upon the cheek . “ D r n a c yo ( Gr . a

’ - - D r Gr. a c yo p s ( dak ré ops ) . ( dakryon tear

2 ops eye . ) A watery eye . Applied to a swell t ing of the lacrimal sac or one of its duc s .

Da c r orr e rh oia . y h a ( Gr . dakryon tear flow ) E xcessive or morbid fl ow of tears . O PHTHALM I C DIC TI O NARY 71

Gr Da c ryopyorrh ea ( . dakryon tear pyon fl pus rh oia ow) . Discharge of pus from the

lacrimal duct .

’ Da c ryo p yo s i s ( Gr . dakryon tear pyosis

suppuration ) . A discharge of tears mixed with

purulent matter .

’ D - - zm - a lto n i s m ( dawl ton i ) . Color blindness .

’ Da - n n s - - y bli d e s ( day blind ness ) . P artially blind by

day, with better vision at night . S ee H emera

lop ia .

’ D eca t - - - m e er ( dek a me ter ) . Ten meters .

’ D ec e t r - - L n e ed ( de cen terd ) ens . A lens with its O ptical center to one side or above or below the

center.

D e cen t ered L en s es .

Decent e ri n g of Lens es . Instead of having a prism a and lens combined , where you wish to obtain

the effect of both , it is possible to get the same result by simply decentering the optical center

of th e lens . The optical center of a plus lens

is at the thickest part , and i n the minus at its

thinnest part , while the geometrical center of a

lens is the point midway between all edges . A

' 1 - dioptry lens decentered 1 0 mm . will give the

° 1 2 -D effect of a prism , while a . lens will only

require to be decentered half this amount , or

- - 5 mm a 3 D . lens , one third of this amount , for

the same effect , and so on according to the

strength of the lens . To obtain the effect of a 72 LE W I S P O C KE T

° 2 pri sm these lenses must be decentered twic e — - D as much that is to say , a 1 . lens , 2 0 mm a

- - 2 D . lens , 1 0 mm . ; a 3 D . , mm . F rom this table one can easily figure the exact amount any lens should be decentered to obtain a given : prismatic effect . La w of D ec ent ra tion A n y lens i s capable of producing as many prism dioptrie s as the lens possesses dioptries of re

— ~ fraction , provided it i s decentered 1 cm . P ren

tice , Archives of O phthalmology , Vol . X IX , No . 1 2 Y 1 890 and No . , New ork , .

’ - - - Dec ent ration (de cen tra tion ) . Th e act of re

moving from a center .

' D - - = ec im a l ( des i mal ) . ( L. decem ten . ) P ertain

ing to ten .

’ - - - - D . ec im et e r ( des i me ter ) . O n e tenth of a meter

Dec m t t o p o s i ion of Ligh . If parallel rays of sun light pass through a prism it is not only re f racted but it is also decomposed into its vari

r r n i ous colors . This is due to the unequal ef a g b ility of th e ~differen t colored rays which form

white light , the violet being refracted the most

and the red the least , thus forming the spec

trum .

’ D - - - L r z t ecu s s ation ( de ku s a shon ) . ( . decus s a e o

cross . ) The act of crossing or intersecting ; the

etc . crossing of two lines , rays , fibers of nerves , Through the decussation of the rays in the pupil of the eye the image of the object ‘on the

retina is inverted .

D ef e ct ( de A departure from the normal . When speaking of defects of vision we mean

the visual power of the eye is not normal .

74 LE W I S P O C KE T

in which the eyes turn to the right when the

extrinsic muscles are in a state of rest .

' ’ - - - Di a ca us ti c ( di a kas tik ) . A curve formed by the consecutive intersections of rays of light re a s fracted through len , and when reflected it is

called catacaustic .

’ - - - = D a . i a gona l ( di g o nal ) . ( Gr dia th rough

2 r gonia co ner, angle . ) A line through the a n

gles of a figure , but not lying in its sides or

faces .

D m t Gr di m tr i a e e r ( . a e os ; dia through metron

measure ) . A straight line joining opposite

points of a circle , drawn through the center .

' D a - - - n - i- i p h a n eity ( di a f a e ty) . Transparency ; the

power of transmitting light .

’ Di a p h a nou s ( di - a f - a - nous ) H aving power to trans

mit rays of light, as glass .

’ D r m - - i a p h a g ( di a fram ) . ( Gr. diaphragma a

“ partition wall . ) A term applied to the partition w ith a central aperture in optical instruments

so that rays of light may be controlled . The iri s with its pupil constitutes the diaphragm of the

eye .

’ - - - - D a es a i e S . i p y i s (di p sis ) . uppuration

’ - - ff Diff ra ction ( dif frak shun ) . ( L . di ra ctus ; diff rin

r = g e e to break up . ) Defl ection or decomposi tion of light in passing by the edges of opaque

bodies or through small apertures .

’ - - Diffus ion ( dif fu shun) . n . ( O ptics ) A spreading or

scattering of rays of light , causing a blurred

image by imperfect refraction .

' D - Th i i L . i git ( d i t) . ( . digitus finger ) e number 1 represented by any one of the ten symbols 0, , O PHTHALM IC DI C TI O NARY 75

i 2 . 9 . The term i s more often used to d es g

nate one of the ten symbol s mentioned .

D t ila ant . A medicine that causes dilatation .

’ t - - — Dil a atio n ( di la ta shun ) . (L . dilatare to ex

pand . ) The expansion of any orifice or can al .

’ D at r -l - i il o ( di a tor ) . Dilator iri s refers to the ra d at

ing fiber of the iris which dilates the pupil .

’ D t - - io p er ( di op ter ) . ( Gr . dia through op s oma l

I shall see . ) A leveling instrument of ancient

times , equipped with sights at both ends and a

water level in its center . The theodolite , by

H ipparchus , the ancient Greek mathematician .

' D t m t - - - e - An io p o e e r ( di op tom ter ) . instrument for

testing ocular refraction .

’ D t t r - - i - - io p om e y ( di op to n e tre ) . The measurement

of ocular accommodation and refraction .

D t r - w io p al , a . Applied to the refractive po er of ophthalmic lenses numbered accord-ing to the

metric system , and in which the unit of power

1 - has a focal length of 1 meter . Thus , a dioptry lens is S pecifically a member of the dioptral

- system , whereas a 40 inch telescope lens is a

member of a dioptric system .

’ - - Dio pt ri c (di op tric ) . S ee Dioptry .

’ - - - O Diopt ri ca l ( di op tri kal ) . f or pertaining to

dioptric .

’ - - Dio pt ri cs ( di op trics ) . That branch of optics which treats of th e refraction of light by any

W . transparent media , as air , ater , or glass

’ - - S . en Diopt ron ( di op tron ) . ( urg ) A dilating spe

i lum.

' e - D t r n di o . Gr. o s o io p y, . ( p tri ) ( dia through p th e mai I shall see . ) The unit for expressing 76 L E W I S PO C KE T

f re ractive power of a lens . The refractive power of a lens which will focus parallel rays of light

at a distance of 1 meter . A lens of 2 dioptries

( 2 D . ) has a focal length of meter . S ynonym s : D ioptre , D ioptric . S ee F ocus

’ D c r - -k o - r - i plo o i a ( dip lo e ah ) . ( Gr. dip lous dou

ble kore pupil . ) Double pupil .

’ D - - - i p lo p i a ( dip lo p e ah ) . (Gr . diplons double

o s is z i i p v s on . ) Double vision ; seeing one ob

e ct j as two . The obj ect of convergence is to direct the yellow S pot ( or macula lutea ) in each

eye toward the same point , so as to obtain

single vision ; diplopia , or double vision , at once resulting when the image of an object falls on parts of the retina which do not exactly corre

s on d p in the two eyes . B ino c ul a r d . , double vision only when th e two

eyes are exposed to view . H et e ronymou s d . , where the object seen w ith the right eye a p

on pears the left side , and that of the left eye h on the right S ide . H omonymou s d . , w ere the obj ect of the right eye appears on the right side

and the obj ect of the left eye on the left side .

Mono c ul a r d . , diplopia with a single eye .

’ D t - - - - - i p lo p iom e e r ( dip lo pi om e ter ) . An instrument

for measuring diplopia .

D i s c ( disk ) . A round body which resembles a

t . small circular plate . O p i c d , a whitish circular spot in the retina representing the entrance of

the optic nerve into the globe of the eye .

’ - - D . i s c i s s io n (dis i sh un ) . ( L . discindere to split ) The rupture of the capsule of the crystalline

lens in the operation for soft cataract .

D th e e e i s ea s es of t h e E ye . The diseases of y are O PHTHALM I C DI C TIO NARY 7 7

many , but nearly all of them can be directly or

indirectly attributed to eye - strain or impurity

- of the blood . F irst , relieve any eye strain by

glasses ; second , keep the bowel s regular ; third , “

fresh air and exercise . When th e patient re

quires further attention , p rop er treatment

S hould be instituted .

’ D a ra te P o n ts - - i r r = t i s p i ( dis par at ) . ( L . d s p a a e o

separate . ) P oints on the two retina e upon which

light does not produce the sam e impression .

D s e r L dis ers us dis er er = t t i p s e ( . p ; p g e o sca ter

about ) .

’ - - Di s p e rs i n g Le n s (dis p er S in g ) . Same as concav e

lens .

’ D - - T i s p e rs i on ( dis per S hun ) . h e process of scatter

ing the rays of light through any kind of a lens .

’ ’ h D - -k - - - - - Dist i c ia s is , i s ti c hi a ( dis te i a sis , dis tik e ah ) . n ( Gr. di double stichos row . That co di tion of the eyelashes in which a s econd row

m tiOn . rub s against the cornea , causing in fl am a

’ - - di = art Di v erge n c e ( di ver gens ) . ( L . ap + ver z T t n m gere to incline . ) o ur outward fro

parallelism .

’ - - = Div i de n d ( div i dend ) . ( L . dividere to divide . ) A number or quantity to b e divided by another

- i s called the dividend .

Donde rs ( F ra n s Co rn eli s ) . A Dutch physician , M 1 wa s born at Tilburg , Holland , ay 2 7, 1 8 8 . H e

educated at Utrecht , where he became a pro

f es sor of physiology .

m - Dou bl e P ri s . An opaque disc found in tes t case

- - with a S li t like O pening . O ver thi s S lit there

are two prism s with their bases together . U sed

for testing for muscular imbalance . To test f or muscular imbalance use a small round bright 78 LE W I S PO C KE T

1 frosted light ( about to 4 inch , at 2 0 feet ) , the double prism will make this light appear as

two , both of which will be displaced from their t true posi ion . O ver the other eye p lace the red

glass di sc which will color the light red . The t patient will then see hree lights , two white ,

one red . If the red light is seen midway b e

tween th e two white , no muscular imbalance i s

present ; if n et, the prism that will bring it

there is the measure of deviation . The two prisms used in this disc are of five diopters h each , joined base to base . When t e line formed by th e bases i s placed horizontally before the

pupil of an eye the light will be seen as two , i ll s ep ara ted , vert ca y from their true position h leaving th e other eye , whic is wearing the red

o . glas s disc , t see the light in its true position

S ee Dou bl e Vi s ion . S eeing one object as two .

D iplopia .

’ - Dou bl et ( doub let ) . Composed of two lenses .

Du ct ( dukt ) . A tube for conveying a fluid .

D ura Mat e r. The outermost membrane of the

brain , spinal cord , optic nerve , and capsule of

Tenon .

Du ra l S h ea th . The external covering of the optic

nerve .

’ - - - Dyna m et e r ( dy nam e ter ) . An instrument for de

termin in g the magnifying power of telescopes .

Dyna mi c ( Gr. dynamis power ) . The powers

whereby bodies are put in motion .

’ - - r Dyna m i c Ref ra ct ion ( dy nam l o) . ( G . dynamis ( power . ) The refraction of the eye dioptric power ) while using all of its accommodation

and adjusted for the near point of vision . The O P H T H A L NI I C DI C TI O NARY 79

difference between the dynamic and static re fraction is known as the Amplitude of Aecom

m i n oda t o .

’ ’ D n a m c S a met r - - ic - a m - e- y i ki y ( di nam sky try ) .

2 ( Gr. dynami s pow er S kia shadow met

ron measure . ) Is defined as the measuring of the refraction of an eye by the shadow test ( retinoscopy ) while the accommodation is under

tension . It i s the opposite of static S kiametry,

where the accommodation is relaxed .

The value of dynamic S kiametry i s said to b e in its offering a mechanical means for absorb

ing spasm s of accom modation , and thus reveal ing latent errors without recourse to cy clop l eg

ics . In the practice of the dynamic method the patient i s required to accurately fix his vision on a test card that is situated the same distance 1 away ( say , 6 inches ) that the nodal point of an examiner ’ s eye ( behind the peephole of his skiascope ) i s situated during the examination ;

f x t n erv t n that is , the i a io and o bs a io must b e

U ‘ exactly the same . nder these conditions , if the examiner w ill keep adding a ll the plus spherical lens power possible before reversal of the shadow takes place ( even though the shadow does not indicate hyperopia ) it will be found that an eye will surrender that portion of its accommodation which is in ex c es s of what is needed to correctly harmonize with the con vergence required for the distance at which the

examination is made . With the dynamic method no allowance in strength of lens i s made for the

working di stance , as by the static method , and where the patient is presbyopic or has la tent 8 0 L E W I S PO C KE T

hyperopia there will be a di fference in the fi n d

ings between the dynamic and static .

The recognized text - book on the subject is “ calle“d D ynamic S kiametry in Theory and P rae

tice , by Andrew Jay Cross , D . O . S of Columbia U Y niversity , New ork C ity , who i s the origi

nator of the method .

’ D n m - - - - y a om et e r ( dy na mom e ter ) . An instrument for measuring force or power ; especially the

muscular power .

’ ’ D n mmt - - - - y a o e ry ( dy na mom e try ) . The process of

measuring force while doing work .

’ D - - - s ex . y l i a ( dis lex se ah ) ( Gr . dys bad lexis

word . ) Inability to read caused b y a disease

of th e brain . Vision is good , but the power to

read i s wanting .

’ D s o s - - O s is y p y ( dys op s y ) . ( Gr . dys faulty p

vision . ) Dimness of vision .

’ ’ C C E N k - - k E T R IC ( e sen trik ) . ( Gr . e out k e n tr n . f o center ) Away rom a center .

E c c m Gr k ut ch m hy o s i s ( . e o y os juice ) . An t f t t ex ravasation o blood in o issue .

E cta s i a ( ek Abnormal distention or

dila tation of a part .

' ’ E k - - k t r . r . c i i s ( e ti ris ) ( G . e tos outside iris ) The external portion of th e iris

' E k - - - - - k cto c ho roi dea ( e to cho roi de ah ) . ( Gr . e tos

t l th . outside . ) The ou er ayer of e choroid coat

’ k - - - - E cto c o rn ea ( e to kor n e ah ) . O uter layer of the

cornea .

8 2 L E W I S PO CKE T

while thet muscles of accommodation are in a t s ate of rest . E mm etropia h as no reference whatever to

th e sight , or disease , but simply means that optical apparatus has ‘ the correct focal length

for the globe of the eye . In other words , no lens

i s required for distant vision . When this condi

tion does not exist the eye is out of measure , or

ametropic . E ’ mphys e ma ( Gr. en in p hys ema a blow

ing ) . The infiltration of air into the cellular

tissues of the orbit . M ay be caused by rupture

of the lachrymal sac .

’

k . E n ca n t hi s ( Gr. en in an th os canthus ) A

minute tumor in the inner canthus of th e eye .

E n doth eli um ( Gr. endon within thele nip

ple ) . A layer of flat cells lining serous cavities ,

- blood vessels , and lymph atics . The fifth layer

of the cornea .

E n e rgy. ( P hysics ) Capacity for performing work .

- - E n e rvat e eu er . ( vate ) To deprive of nerve , force ,

or strength ; to render feeble .

’ - — - E n t n . o p h ha lmus ( e of thal mus ) ( Gr . en in h op h t al mos eye . ) A condition where the eyes

- are deep seated .

‘ E n s t ro n - -f Gr en ph e ( e stro e ) . ( . in strophe

a turnin g ) . A turning inward .

’ E n en tos tad ( Gr . within ) . Toward a center .

’ n - - - - — Gr en tos E n t ho ro dea e . oc i ( to cho roi de ah ) ( .

h r wi thin c o ioeides choroid ) . The inner layer

of the choroid .

' - - - - - r n t s E n tocorn ea ( en to cor me ah ) . ( G . e os wim

’ in . ) D escem et s m embrane . O PHTHALM IC DI C TIO NARY 8 3

’ E n t t c eu- - n 2 r . op i ( top tic ) . ( G e tos within op

tikos visual . ) S ituated within the eye .

’ ’ E n topti c P h e n ome n o n ( eu- top -tic phe - nom - e - non

That which is peculiar with itself , such a s M uscae Volitantes .

’ E n t t s c m- - - - o p o o p y ( e top tos co p y ) . (Gr . en tos o tos k within p visible s op eo I view . )

Inspection of th e interior of the eye .

’ E t ret e n - - - - n o ina ( to ret in ah ) . The nervous or inner

layer of the retina .

E t r n o p ion ( Gr . en in trop e a turning) . S ee E ntropium .

’ E n t r m u- - - o iu ( e tro pi um ) . A turn in g in or inver p _

sion of the eyelid or eyelashes .

’ E n c ea t - - - u l e ( e nu cle ate ) . ( L . e from nucleus

2 kernel . ) To remove from its cover .

’ ' E c ea t - - - - h t n u l ion ( e nu cle a s un ) . O pera ion for the

removal of the eye . “ ’ “ E r p hi d o s i s . ( Gr . I sweat . An excessive se

cretion of the sweat glands of the eyelids . It

s cause itching , irritation . and inflammation of.

the skin and conjunctiva . It is d ifficult to cure .

’ E a n t s -i- - e i z u on — p i c h u ( ep can thus ) . ( Gr. p p l = t k a n th os ca n th us . ) A fold of skin projec ed

over the inner canthus .

’ - - - E r e r . G a p i p ho a ( pif o a ) ( r. epi upon phori

tend ing . ) An overflow of tears , causing them

to run down the cheek .

E e r kl r s e os . p i s cl a (Gr . epi upon hard ) The connective tissue between the sclera and th e

conjunctiva .

’ E s - i- - p i cl era l ( ep s cl e ral ) . S ituated over the sclera

of the eye . 84 LE \ V I S PO CKE T

’ E - - - - p i s c l e riti s ( cp i s cl e ri tis ) . Inflammation of the

outer layers of the sclera . E ’ p ith elio ma . Cancer composed largely of e p ith e

lial cells , and is the most frequent of malignant

growths affecting the eyelid . It seldom appears

before the age of forty .

’ - - - E t m e i d u . p i h eli u ( p the e m) ( Gr . epi upon

z: - . t thele nipple ) The non vascular , ex ernal

th e m layer of skin and ucous membrane . F irs t

layer of the cornea .

’ - = . L ae ualis e ual . Eq ua l ( e kwal ) ( . q q ) H aving

the same value .

’ - - Equati on ( e kwa shun ) . A propositio n asserting the equality of two quantities and expressed by

n the S ign between them . I Algebra , an equality which exists only f or particular values

of certain letters called unknown quantities .

E te r kwi L a e uus = e ual quil a a l ( e L . q q

'

latus side . ) H aving all of the sides equal .

’ E r t O r t . q uil i b a ing p e a io n Tenotomy of the muscle . which antagonizes a paralyzed muscle of the

eye . E rro rs of Ref ra cti on . Abnormal conditions of re

fraction in the eye .

’ e - th r fi r ed r t r s a . er os y h o p i ( erythro psia ) . ( Gr y

op s is vision . ) R ed vi sion ; a condition in

wh ich all objects appear to be tinged with red .

’ E - - s erin e ( es er een ) . An alkaloid obtained from

- the calabar bean , which will cause contraction

of the pupil . It has an action exactly opposite to t hat of atropine , since it places the iris and

ciliary muscle in a state of tonic contracti on .

Consequently , m iosis develops , so that th e pupil ’ w i s about t h e size of a pin s head . ith adjust O I HT H A L M I C DI C TI O NA RY 8 5

' th e e e m ent of y for the near point , as if

marked myopia were present . We generally 1 apply sulphate of eserine in per cent solution .

This solution , when freshly prepared , is color

‘

less , but after some days becomes red , although

without losing its activity . The instillation of “

eserine produces , simultaneously with th e

- n cha nges i the iris , a feeling of great . tension

th e in eye , and frequently headache , and even

nausea , so th at with many persons it cannot be “ v emp lo ed . F or this reason , hydrochloride of 2 r pilocarpine , prescribed in a 1 to p e cent solu

tion , i s recommended as a miotic for ordinary t use . Its solution keeps better than tha of

eserine , and does not act as powerfully as the

un l ea s latter , but is not accompanied by any p E ant complication . serine is best reserved for

those cases in which pilocarpine is ineffectual .

’ - -fo - - es o : in ward E es . s o p h ori a ( o ri ah ) ( Gr .

phoria a tending . ) That condition of the eyes

in which the visual axes , although parallel when

I n in use for distant vision , deviate nward whe

the extrinsic muscles are in a state of rest .

’ - - - - s o = in w ard Es ot ro p ia ( e s o tro pi ah ) . ( Gr . e + z trope turn . ) This term expresses a stronger

meaning than E sophoria , in which there is E merely a tendency , while in sotropia there i s a positive and visible appearance of the eyes

turning inward .

’ v - - - = to un E ol utio n ( cv o l n shun) . (L . evolvere

roll . ) The extraction of roots from powers .

’ Ex - - - re to cavatio n ( ex cav a shun) . (L . excava

hollow out . ) E xcavation of optic nerve ; cupping

or hollowing of the optic disc . 8 6 LE W IS PO C KE T

’ - - - - = E Gr . x tw r x op ho ri a ( ex o fO ri ah ) . ( e o ou a d

phor a tending . ) That condition of the eyes

in which the visual axes , although parallel when

n in use for distant vision , deviate outward whe

th e extrinsic muscles are in a s tate of rest . The internal rectus muscle s are overworked f rom this continual convergence and relieved

s only when the l id s are closed , or pri ms worn ,

u to th e base in , that are strong eno gh bend light t to suit . th e eyes in thei r deviating posi ion of

rest .

’ ’ E x c ht h a lm ic t e r k - - - - p Goi ( e s off thal m ik goi t er) . A g oiter w ith exophthalmos and cardiac palpita B ’ ’ tion ; asedow s disease ; Graves disease . Th e most prominent symptoms are protrusion of the

eye , excited action of the heart , enlarged thy

r oid ( goiter ) , an d certain nervous phenomena .

The protrusion is almost invariably bilateral , though not infrequently grea ter on the right

S ide . The upper lids do not follow the eyeball

’ in looking down ( Von Graefe s S ign ) : in fre q uen cy of involuntary winking ( S tellwag s S ign ) and abnormal width of the palpebral apertur e

are also found .

’ - - - 2 E . x ophtha lmo s ( ex of thal mos ) ( Gr . ex out A th e op h th almos eye . ) bnormal protrusion of

eye .

’ Ex or b t s m ) . P ro i i (L. ex out orbita orbit

trusion of the eyeball .

' - - - - Gr . Ex ot ro p i a ( ex o tro pi ah ) . ( exo outward d trope turn . ) When the eye is turned outwar

D S . from parallelism . S ee ivergent trabi smus

’ - - trah ere = tu L . ex Ext ract ion ( ex trak shun ) . ( O P H T H A L IVI I C DIC TIO NARY 8 7

draw out . ) The removal of a body by surgical

means .

’ Ext ra va s a t on ek s - tr h 4 - - r i ( a vas a shun ) . ( L . ext a out The escape of fluid s

from their proper vessels , into surrounding

tissues .

k == u r~ Ext re mes ( e s ( L . extremus o te

most . ) The first and last term s of a proportion

or of any other related series of terms . ’ M Ext ri n s i c . O f exterior origin . E . uscles ar e

those on th e outside of the organ .

. T h e Eye ( L . oculus eye ) . The organ of sight

’

function of each eye , taken singly , is to form

upon the retina , or nervous membrane which L E W I S PO C KE T

lines the inside and back part of the organ , a S harply defined inverted image of an y objec t

’ looked at . The eye resembles a photographer s

' camera in a s much a s the image produced upon the retina is precisely the same as that pro

d uced - on the ground glass of a camera . B y m eans of the optic nerve the image that i s re

c eive d On the retina i s conveyed to the brain , which recognizes the visual appearances and m co pletes the act of seeing . M ore than thi s we d o not know , but we do know that it depends upon th e sharpness and clearness of the retinal

image . I f th e image is blurred and indistinct it will be impossible for the brain to recognize th e

object accurately .

E y e b row s . They are two projecting arches of in t ’ egument covere d with short , thick hairs , which

form the upper boundaries of the orbits . ifi id d he S e a . E y e G ro und . T n b ack part of the eye

‘

The F undus . E y e l a s h es . The hair of the eyelids . E y e li ds . The anterior covering of the eye ; that portion of movable S kin with which the eyebal l it is covered or uncovered at will , protecting

from injury by their closure . The upper lid is m th e the larger , the ore movable of two , and is

a l eb supplied by a separate muscle , Ievator p p

are o rae su p eriori s . When the eyelids pen an

’

elliptical space is left between their margins , the extrem ities of which correspond to the

junction of the upper and lower lids , and are

called canthi . The outer canthus is more acute h than the inner , and the lids ere lie in close

contact with the globe , but the inner canthus is r p rolonged for a sho t distance inward , toward

00 L E l S F U C K E T

a t th e g o f th e lid i ma r in s w i th t h e c c t v onjun a . T h e S u bc uta n eou s reo a r T A l i s s ue in v e r r la x d a t s d and elic e , el om ta s a n v fa t con in , a n d is t ex remely lia ble to s erou s fi t t in l ra ion .

P O S T E IU O R ” - P T il l3 P A L P II B R A L T H E C ' ’ U S J l N t T l V A R E M O V E “ 1 . O rig in o f t h e T e s - n o r t u rn ! M us t ie . S up e rio r t l l n l l n e q u t t e r a s s in ' p g t h ro u h I t T rn t h l e u g

3 . I n te io r r O bl i ue M us c l e q . 4 t t A a c h me n t n r H b c r l ul n rl n P a p e b ra ru m t it e l x s ‘ l t \ ' l . 5 . T u rs n l C a rt i e l a g s s h o win o s o g p it i n o f M e itm m l a n ( iluml s 0 ! O e n in e p g b t w e e n t h e l id s ‘ k n o w n u t t h e l xs l l te l t ru l F ‘l lfl l re

0 L o w e r p a rt o r O - rb it n is rin P a l p e b ra rum N T h e in s e o r t i n o f ( e e ~ ‘ h T n s o r | n rs i M n m e e ‘ ‘ l n a r t h e l l t h t l a it . l a c h ry m a Ru t I n t h e mu m l .

E e y ec e . Th e s pi len or combina tion of len s e s a t th e e e e n d o r u t y el e s cop e or o ther op ti c a l in s t e t t r w rum n . h ou g h h ie h th e im a g e formed h v the objec t l a s s is vie wed g .

E es t y g . s s s i h The en e of eein g : s i gh t of the e ye ; v iew in g : bs e v t o r a ion . O PHTHALM I C DI C TIO NARY 9 1

’ T O f k - Z n F AC R ( a tor ) . ( L . facere to do . ) O e of two or more numbers which when multiplied

together produce a given number .

’ F t t - - - a c v L . ul a i e ( fak ul ta tiv ) . ( . faculta s faculty ) The power or ability to maintain extra effort

whenever called upon .

F l in E a l g y el a s h es . ( S ee M il p h a e and Madarosis . ) F a l s e Im a ge . The image seen with the deviating

eye .

F s M a l e yo p i a . D ue to a spasm of accommoda

th e tion , where crystalline lens i s kept con

vexed by the spasm and simulates true myopia .

F P a r oint . The far point or punctum re motum is the most distant point at which an obj ect may mmo be seen clearly , with th e muscles of a cco

t . P f r da ion at rest roperly speaking , the a point t is an optical and not a visual point , and is tha point from which rays of light will focus on

th e . the retina , eye being in a state of rest

’ F - e - S a s c i a ( fash ah ) . A band or heet of tissue

connecting and investing muscles .

F V i e l d of i s ion . The area or space which the

fixed eye can see .

F t t A n il ra ion gle . ( S ee Iritic Angle . )

' F s r fi h - fi n d = t i s u e ( s ur) . ( L . o o split . ) l n anat

om P a e r f s s r y , a cl eft , or slit . l p b a l i u e is the

opening between the margins of the eyelids .

S ph enoi da l fis s u re i s a large S plit- like opening

si tuated in the upper and back part of the orbit . S p h eno -m a x ill a ry fi s s ur e is an opening in the

back part of the orbit between the sphenoid ,

maxillary and palate and malar bones . C h o 9 2 LE W I S PO C KE T

rol da l fis s ure is the opening in the choroid through which the optic nerve passes to form

the retina .

E x t R Fla p t ra c ion . emoval of cataract by making

a flap in the cornea . k Flo a ting S p ec s . S mall floating opacities in the

S e M humors of the eye . ( e usc ae Volitantes . )

’ F - f . P c a o . F . D t o l ( kal ) ertaining to a focus e p h ,

penetrating power of a lens . F . Di s ta n c e , dis tance between the center of lens and its prin

cip a l focus .

F Le t o o ca l ng h f Le ns es , in inches , centimeters and millim eters taken from the basis of forty

inches as the equivalent to one meter .

E n g l is h I n c h e s 3 3 3 1 60

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 O PHTHALM IC DIC TIO NARY 9 3

D io p trie s C e n t im e t e rs

5 5 0 a The above table is approxim tely correct , yet

there is a slight difference in close figuring , but is correct as far as the optometrist is con

1 - cerned ; for instance , a D . lens has a focal

length of inches , while we call it 40.

F oca l P l a n es . Straight lines through the foci per

p en dicul a r to the principal axis .

’ F - Th o c us ( to kus ) . e point produced by light

t P r n c coming to or going from a point . Fi rs i i p a l Fo cu s is a t the point the light leaves as divergent rays and emerges from the optical 9 4 LE W I S PO C KE T

to system as parallel the principal axis . T h e S econd P rin c i p a l Foc u s is th e point where the emergent rays cross each other when the inci ' dent rays have been parallel to the principal

e t e F axis . N ga i v o cu s i s the point from which

rays of light appear , to , but do not come from , th e . S focus of a minus lens ec onda ry Fo cu s .

Any focus of the secondary axis .

F t ogging S ys em . The system of fitting glasses by first making the patient artificially myopic by

means of plus spheres , if they are not already

myop ic , the idea being to relax all accommoda t ion before using cylinders .

F e r - old s . A term employed for eye glasses that

can be folded up and placed in a small pocket .

’ F c - ik -l L f l i = . . ol culus a olli le ( fol ) ( small bag . ) A small secretory cavity or sac .

’ F - - - c a r ik . olli ul ( fol u lar ) Containing follicles . F .

Conjun ct i v it i s . A form of conj unc tivitis marked

by the presence of follicles . This occurs gen

r ll z h e a y in children , and is characteri ed by t e t forma ion of small , Clear elevations , consisting

th e of adenoid tissue , in th e conjunc tiva of lower l id ; in some cases they are present also h th in t e retrotarsal fol d of e upper lid .

F t I on a n a , S p a c es of . n the anterior chamber of th e eye , where the corneal margin j oins the

base of iris and sclerotic , we find a number of delicate bands of ti ssue pa s sing from th e mem

brane of D escemet to th e ba s e of the iri s . These are known as the ligamen tum p ec tin a tum iridis

and between them small comb - like openings

’ leading into S chlemm s Canal , known as the

S paces of F ontana . O PHTHALM IC DI C TIO NARY 9 5

’ - - m L . Fora e n ( to ray men ) . ( foro to bore a hole . ) A hole or opening through any bone or a mem

b ra n ous structure . l n f ra orb ita l F . , the external

n opening of the infraorbital canal , on the a terior surface of the body of the m axilla ; o pt ic

F . , the opening between the lesser wing and body of the sphenoid transmitting the optic

n erve and ophthalmic artery . ( F or other fora

men , see under orbit . )

F r e . L o c ( . fortis strong . ) ( P h ys icis ) Any

action between two bodies which changes , or t tends to change , their relative condi ion as to

rest or motion ; or , more generally , which

change s or, tends to change , any physical rela

tion between them , whether mechanical , chem

ical , or any other kind ; as , the force of gravity .

- F x L . . orn i . ( arch , vault ) A vault like space .

Forn ix C on j un ct iva . The turn or fold of the con

jun ctiva .

' Fos s a e P at ell a ris ( p a-tel -la -ris ) ( meaning dish

like depression ) . The depression in the anterior surface of the vitreous body in which the crys

l in ta l e lens lies . Also called the H yaloid F ossa .

F . . os s a . ( L . a ditch ) A pit , cavity or depression

’ - - = F v v L . o ea ( foh e ah ) . ( . fodio to dig ) A small

depression . F . C e n t ra li s is employed to des ig nate th e little depression In the center of the

macula lutea .

’ - = F r k L fr n r . ra cti on ( f a shun ) . ( . a g e e to break )

O n e or more of the equal parts of a unit .

F ra me Fitti n g. There are tim es when patients t complain that their glasses are not comfor able ,

yet they have the right correction . The cause L E \Vl S PO C KE T

of the trouble i s sometimes found in the im~

proper adjustmen t o f th e frames . The fitting of

ta t t a frame is very impor n , and if neglec ed will s ometimes destroy th e benefi t of th e most care

t s fully fitted lenses . When a s udent understand th e relation between accommodation and con v ergence the value of frame fitting b ecomes t easily unders tood . A convex lens , wi h its

v cur ed surfaces , may be described a s made up o f an infinite number of pri sm s with their

ba s es meeting a t the center ; a concave lens , in

n a like manner . i s made up of a infinite number

F ra me it tin F g .

of t t prisms wi h heir bases outward . When a person looks through th e inner side of a convex l ens , as he i s compelled to do when the frames a re t too wide for the pupillary dis ance . he i s t looking not only hrough convex lenses , b ut al so through prisms with their bases outward ; when th e frames are too narrow he looks t t hrough pri sms wi h thei r bases inward . With concave lenses , of course , this condi tion will

be reversed . and besides giving a prismatic

9 8 L E W’ I S PO C KE T

press on th e fl esh . If you desire to tilt th e

lenses do not bend temples , but bend the end

piece . All glasses should tilt outward from the t top , but reading glasses more than distan ones . Cylinders should always be worn as spectacles , as it is very important that they should b e held

in their correct position . It is always best for one who is just com men cin g to practice to supply him self wi th a

full set of measuring frames . They are p ut up

and sold by all wholesale optical houses . The optical houses also supply cards on which are

printed the various dimensions . Then by fin d ing a sample fram e among your set that about

' fits your patient you lay it down on the card ,

allowing for any change you wish to make , and

you can easily figure the exact dimensions .

’ - F . un ct io n ( funk shun ) ( L . functio toexecute . ) The special duties which an organ or group of M t organs has to perform . ( ath . ) A quan ity so connected with another quantity that if any alteration b e made in the latter there will be a E consequent alteration in th e former . ach

quantity is said to b e a function of the other .

Thus , the circumference of a circle is a function

of the diameter .

’ - Fundus ( fun dus ) . That portion of a hollow organ

farthest from the entrance . The fundus of the

eye is seen by m eans of the ophthalmoscope ,

namely , the retina , blood vessels , choroid . optic

disc , collectively .

' - = k . Fu s ci n ( fus S in ) . ( L . fus cus dus y ) A brown

pigment of the retinal epithelium . O PHTHALM IC DIC TIO NARY 9 9

’ G A G L O - - n Gr N I N ( gang gle o ) . ( . a knot . I n

- anatomy , a knot like aggregation of nerve cell s .

It is a partly independent nerve center , with dis tinct functions in connection with nearby strue

a r G . tures . C ili y , sometimes called ophthalmic i z ’ or lenticular , s about the S i e of a pin s head ,

situated in the back part of the orbit , between

th e external rectus muscle and the optic nerve .

The three nerves which enter it are , one from

th e nasal branch of the ophthalmic ( sensory ) , one from a branch of the third nerve ( motor )

and a roOt of the sympathetic . F rom it passes off about ten filaments which pierce the poste rior part of the sclera supplying the ciliary

G s s e r a n muscles , the iris and the cornea . a i or

S emi l un a r G. l ies in a depression (cavum M eck el ii) oh the anterior surface of the petrous t por ion of the temporal bone near the apex . It is a flat expansion on th e sensory root of the

( fifth ) trigeminal nerve , receiving on its inner s ide filaments from the carotid plexus of the

sympathetic and giving off the ophthalmic ,

superior maxillary and inferior maxillary . The

ophthalmic nerve i s a sensor nerve . It supplies i sensation to cornea, ciliary muscles , ris , lach

rimal gland , mucous m embrane of nose , skin of r J b e eyelids , eyebrow s , fo ehead and nose . ust h fore entering t e orbit , through the sphenoidal

l ach rimal fissure , it divides into three branches , ,

frontal and nasal .

Geo met ri ca l C e n t e r. A point midway between al l

0 edges . = m i . omet r . eo etr a to Ge y ( Gr . g measure ) That 1 00 LE \ V I S PO C KE T

branch of mathematics which I nves tigates th e .

relations , properties and mea surement of solids , .

surfaces , lines and angles ; the science which treats of the properties and relations of magni

tudes ; the science and relations of space .

G n e r m L e i c Co p o un ds . enses having spherical and cylindrical curvatures of the same S pecies ;

t . that is , both convex or bo h concave Con

r n ri t a g e e c compounds have one surface convex ,

the other concave .

G ’ Gl ’ lum S l a b el l a , a b e l . ( L . glaber s mooth . ) pace

between the eyebrows .

G a d . z to l n ( L . glans acorn . ) The name applied organs which separate from the blood any fluid

whatever .

’ B - ruc h s Gl a n ds . The lymph follicles of the

’ r conjunctiva . H e nl e s G la nds a e a number of follicular cavities formed by irregul ar fol ds

in the epithelium Of the tarsal conjunctiva .

’ K ra us e s Gl a nds , the tubular glands which lie

at the border of the tarsi near the fornix . These

a r are regarded as accessory glands . C ili y r Gla n ds are the sweat glands of the eyelids and located in several rows close to the free margi n

Th e a re G a n ds of the lid . y_ _ also known as the l

of Moll . Lac h rima l Gl a nds , th e glands which.

d res secrete the tears . They are located in a ep sio n of the frontal bone at the upper and oute r

d o angle of the orbits . The gland is divi ed int

two parts , the superior and in ferior and a t ta ch ed to the bony reof of the orbit fiy th e

- t in r itgtl . tarso o b fascia The ducts , abou ten I ts n th f . umber , open into e ornix conjunctiva nerve s upply i s the smallest of the th ree

1 02 LE W I S PO CKE T

t S F s hus closing the paces of ontana , the drain

age system would be blocked , while the humors t continue forming , resulting in . a painful in ra

ocular pressure . Glaucoma may be divided into P two kinds , primary and secondary . rimary, w hen it makes its appearance in a healthy eye , S or with a disease like cataract . econdary ,

when caused by a disease like iritis . It is a

p rogressive disease , and unless checked by

treatment ends in permanent blindness . S t m 1 P ym p om s of Gl au co a . ( ) ain , sometimes

o f a neuralgic character . ( 2 ) Increased tension

of the eyeball , sometimes becom ing stonelike . ( 3 ) Rapid failing of the power of accommoda

tion . ( 4 ) Dimness of vision . The pupil is

dilated and sluggish . ( 5 ) The patient complains of seeing flashes of light and colored halo

around a flam e or candle . ( 6 ) Cupping of the

optic disc . ( 7) Conjunctivitis . The iris also

appears steamy . When glaucoma i s suspected th e patient S hould be sent to an oculist at once . The use of atropine causes the iris to crowd h into the periphery of t e anterior chamber , somewhat occluding the S paces of F ontana and h interfering with the free exit of aqueous umor .

As the intraocular tension increases , the stop

page becomes more complete . When the atro p ine i s discontinued the sphincter muscle of the pupil draws the iris away from the S paces of

F ontana and th e normal outlet is again opened .

As age advances , the sphincter loses its power , and frequently in ol d people fails to pull the iris

away from the S paces of F ontana , and this con r dition may result in glaucoma . F o the reasons O PHTHALM IC DI C TI O NARY 1 03

m " entioned it is , as a rule , unsafe to use atro f pine after the ages o from 3 0 to 3 5 .

’ G m t - - t- la uc o a o us (glau kom a ous . ) O f the nature

of glaucoma .

’ G m - - lio a ( gly oh mah ) . ( Gr . gli a glue oma , )

‘ A malignant tumor of the retina .

’ Glio s a rco ma . Glioma combined with sarcoma .

’ - - = Glo buli n (glob u lin ) . ( L . gl obul us gl obul e . ) A

protei d from the lens .

Goggl es . S pectacles with wire screens for the

eyes .

’ - t . L . n Goi e r (goi ter ) ( . guttur throat ) An e

E x largement of the thyroid gland . op hth al mi c 9 . E ( S ee xophthalmic Goiter . )

’ Gon rr e = m a O t m . on n o h l p h h a l ia ( Gr . g os s e e rh i o a fl w h h lm . a o . O p t a us eye ) The most

acute form of purulent conjunctivitis . It i s caused by the introduction of the urethral dis

charge to the conjunctival sac .

r d a ted T n t m L . G a u e o o y. ( . gradus a degree . Gr z n tenon z tendon tome incisio . ) An in com

p l ete cutting of the tendon of an eye muscle .

T m . L G ra n a r L d ra c ho a . ul i s ( ) ( granulum , dim of

g ran un ra in . ) R oughness and soreness of

the insid e of the eyelids . This roughness i s

‘ - ca us ed b y a swelling of the lymph corpuscles ,

forming , as it were , little lymphatic gland s or

lymphatic follicles .

’ Gra n u e . . n e l A small rounded body . G Layer, o

of the layers of the retina .

’ G r v t - - = a i . L . The i y (grav ty ) ( . g ravita s h eavy )

state of having weight . ( P hysic s ) The ten deney of a mass of matter toward a center of 1 04 L E W I S P O C KE T

tt t . S a rac ion peci fic gravity , the ratio of the weight of a body to the weight of an equal volum e of some other body taken as th e stand

ard or unit . This standard is usually water for

solids and liquids , and air for gases . Thus , 1 9 ,

the speci fic gravity of gold , expresses the fact

that , bulk for bulk , gold is 1 9 times as heavy as

water .

’ G r v tat n -i- - a i io ( grav ta shun ) . The act of gravi t t P a ing . ( hysic s ) That kind of attraction or force by which all bodies in the universe tend

toward each other .

r v . G roov e ( oo ) A furrow , crease or sulcus . A g ,

narrow , elongated depression on any surface .

La c h rima l G . , the bony channel which lodges

the lacrimal sac . It is located at the anterior

and inner part of the orbit ; cav e rnous G . , ca r

ot id s ul c us , the groove on the upper surface or the sphenoid bone supporting the cavernous

sinus and the carot id artery ; o pti c G . , a groove on the upper surface of the sphenoid bone b e tween the optic foram en in which rest the optic

commissure .

’ H A LL E R S CI RC LE S . Arterial and venous

circles within the eye .

. H a lo . ( Gr . halos a circular threshing floor ) A

reddish yellow ring surrounding the optic disc .

’ ’ H a lo Gla umato s us . A whitish ring around the

optic disc in glaucoma . ’ t m S H a lo S ym p o . eeing of colored rings around

t . lights . This is a symp om of incipient glaucoma

’ H ec to mete r. O n e hundred m eters .

1 06 LE W I S PO CKET

’ et e r met ro a -er- o- - - - H o p i ( het me tro pi ah ) . ( Gr. het eros other metron 2 measure —i ops

eye . ) That condition in which the refractive

power i s unlike in the two eyes .

’ ete ron mo s -er- ou -im- u H y u (het s ) . (Gr . h eteron

mos = h a vin y g a different name . ) Cros s ed .

S ee D iplopia .

’ ete r h ra a . P H o p o l gi ain with heterophoria .

’ et ero r -er- - - - a H pho i a (het o pho ri ) . ( Gr. heteros = other phoria tending . ) That condition of

the eyes in which the visual axes , although

parallel when in use for distant vision , deviate in another direction when the extrinsic muscles

are in a state of rest . It is subdivided into

eight kinds . When the eyes have a tendency to turn in it is known as es o ph ori a ; if a ten

e ex den y to turn out , it is known as o ph ori a ; if

o r a tendency to turn up , it is kn wn as hyp e

e re s r pho ri a ; if up and in , hyp o p ho i a , and if up and out: hyp e rex o pho ria ; if a tendency down

‘ w r i cata r a a d , t is known as pho i ; and if down

t or a ex oc ta and in , es o ca a ph i ; if down and out , a

ph oria . Any error of refraction is liable to

bring on H et e ro p ho ri a , and by correcting the

et e r r a error , the H o p ho i may di sappear , though

it may linger for a month or two . Again one muscle may be too short or too long and a

prism will have to be worn , thus allowing the

eyes to deviate in order to avoid strain .

’ . o h H ete ro phtha l mos ( Gr . heteros other p = th almos ey e . ) That condition in which the

irides differ in color .

’ - - - - - H et e rot rop i a (het er o tro pi a ) . ( Gr . heteros

other trope I turn . ) A condition in which O PHTHALM IC DIC TIO NAR Y 1 07

the extrinsic muscles are no longer able to hold the eyes parallel and there i s a positive and

vi sible appearance of their deviating . They

may turn in any direction , as in h et e ro p ho ri a ;

e rt r a h ot ro if upward , hyp o p i ; if downward , yp

ia ca ta t ro ia es t r p or p ; if inward , o o p i a ; if out x ward , e ot roo ia . F or permanent deviation see ,

S trabismus .

’ - = us us . H ip p (hip ) ( Gr . h ip p os h ors e so named

from its irregular movement . ) S pasmodic

pupillary movements , independent of the action

of light .

’ s to - - - = i H i logy (his tol o je ) . ( Gr. h is tos t s s ue +

: logia discourse . ) The science of the minute

structure and composition of tissues .

’ H olmgr en s T e s t A color test with a number of differen t colored yarns represent

ing the various shades of different colors . U sed

for detecting color blindness .

’ m R - - - e t r s h Gr. H o o c n i c ay ( o mo sen tric ) . ( homos

'

2 same k en tron center . ) A conic pencil of

light rays .

m Gr h omon mos = of m n . H o o y o us . ( y the same

‘

D . name . ) S ee iplopia

’ - - - H o rd eolu m (hawr dee o lum ) . ( L . hordeum

barley . ) S ty ; inflammation of sebaceous glands

of the eyelid .

’ z - - L z = H ori on (h o ri zun ) . ( . hori on the boundary

line . ) The circle which bounds that part of

’ the earth s s urface V isible to a S pectator from a given point ; the apparent junction of the

earth and sky .

, ’ - -zn - H orizo n ta l Li n e (hor 1 o tal . ) A constructive

line either drawn or imagined , which passes , LE W I S PO C KE T

through the point of sight , and i s the chief line i n th e proj ection up on wh ich all verticals are

fixed , and upon which all vanishing points are

found . H orizontal plane is a plane parallel to z ' the hori on , upon whi ch it i s assumed that oh

ect j s are projected .

n E t m or e . n H y p i h li u Trachomatous conju ctivitis .

’ ro t r h - - = H o p e ( o rop tur ) . ( Gr. h oros limit + = opter one who sees . ) The fi eld of binocular

vision as seen with the eyes fixed .

H t E o ye . Temporary congestion of the eye . This

is seen in gouty patients .

m L u r me e . A H u or. ( . h to be moist ) fluid ele _

ment of the eye . (Aqueous , crystalline lens a n d

vitreous . )

’ t n n P n H u chi s o s up il . O e that i s dilated on one

side .

' — - h i a l in Gr h s . a n alo . G Hy li e ( ) . ( . y glass ) lassy

’ a t h - l - - H y li i s ( y a i tis ) . Inflammation of the vitre

ous humor or hyaloid membrane .

’ ‘ - - —— a d h a l oid Gr. h al os s H y loi ( y ) . ( y glas i eidos r in resemblance . ) That which esembles glass

e its transparent qualities . H yaloid membran surrounds and encloses the vitreous humor a n d

form s the suspensory ligaments .

rt H ya loi d A e ry . The fetal branch of the central

'

artery of the retina .

t . H ya loi d C a na l , or Ca n a l of S illing The canal h t e . through the vitreous body , occupied by

hyaloid artery during f etal life .

2 L . H y a loi d Fos s a . ( Gr . h yal os glass fossa f di tch . ) The depression in th e anterior sur ace

21 0 LE W I S PO CKE T

parallel rays of light focus back of the retina

with the muscles of accommodation at rest , due

S to the hortness of the eye from before , back

or insu fficient curvature of the dioptric m edia .

— S ubdivided into three classes l at ent, m a nif e s t

'

and t ota l . La t e n t h . has no subdivisions ; i t is hypermetropia that i s hidden by cramp of the

ciliary muscle , and will not relax without the

us e of drugs at the time of fitting , but when

th e correction for th e manifest is worn , the cramp begins to relax and more hypermetropia

becomes manifest . It may take a week or a M year. a nif es t h . is that part found and cor I t rected with the trial case and retinoscope.

is said to have three subdivisions , namely ,

F t t v h . facultative , relative and absolute . a c ul a i e is where the patient has the ability to overcom e

h e r m t ro i e T h e h e a v in e A y p e p c e y . y l s S h ow t h e f o c us o f a ra ra n r i p ll e l y s b e h i d th e e t n a . T h e d o t t e d l in e s s h o w t h e e ff e c t of a c c om m o d a tion u on t h s a m r p e e a y s .

his error by accommodation , and sees well at

. G all distances lasses relieve strain , but do not

improve vision in this case . Rel a t i v e h . i s where

it is possible to accommodate for a near point , b — y converging to a point still nearer in fact ,

by squinting . This eye has blurred vision for

close work , and plus spheres improve vision . O PHTHALM IC DIC TIO NARY 1 1 11

Abs ol ut e h . is W here the error exceeds the

amount of the accommodation , and the patient

is unable to bring the focus to the retina , and d vision is blurre at all distances . The c orrec

tion always improves vision . T ota l h . is the full

amount of hypermetropi a the patient has . F or

instance , we correct the eye with the trial case

- and find 2 D . of manifest ; then by the use of drugs relax any cramp ; and now find th at the

- - same eye has 6 D . of hypermetropia . 4 D . wa s

' - hidden by cramp . Thi s we call l a ten t, 6 D . ,

being the total amount of hypermetropia .

’ - - H yp e ro p e (h i per op ) . A person who has hyper

metrop ia .

’ H e r hi- -o - é - : yp op ia ( per p ah) ( Gr . hyper over

ops eye . ) S ee H ypermetropia .

’ - - - - H yp e rp ho ri a (h y per fo ri ah ) . (Gr . hyper

above phoria tending . ) That condition in o wh ich one of the eyes , alth ugh parallel with

its fellow when in use for distant vi sion , d evi ates upward when the extrinsic muscles are in

a state of rest .

' ’ - - - z- h H yp e rp las ia (h i per pla e ah ) (Gr . yper

above p l a s is a moulding) . E xcessive tissue

formation .

’ — - - f . h e H yp e rt rop hy (hy per tro y) . ( Gr yper abov

; trop h e nourishment . ) An abnormal in

crease in the size of a part or an organ .

’ - - - - h p H yp e rt rop ia (hy per tro pi ah ) . ( Gr . y er s an i above trope turn . ) E levation of one vi

axis above the other .

' - - - h o = b el ow H yp h e mia (h i fe me ah ) . ( Gr . yp

e e. haima blood . ) H emorrhage within the y 1 1 2 L E W IS PO C KE T

’ n e n et 2 H yp og i c . ( Gr . hypnos sleep genesis

. production ) Causing or producing sleep .

’ H n ol e s - - - r yp p y (hip no lep s e ) . ( G . hypnos sleep l e s is z z p a sei ing . ) Abnormal sleep iness .

’ t - - - - - e a h o . r H yp om ro p i ( y p m e tro pi ah ) ( G . hypo

under m etron measure ops eye . ) S ee M B yopia and rachym etropia .

’ r a h i- o- o -r - Gr H y p o pho i ( p f e ah ) . ( . hypo below t phoria ending . ) That condition in which one

of the eyes , although parallel with its fellow

' u t when in se for distant vision , devia es down ward when th e extrinsic muscles are in a state

of rest .

’ - - - o on h i o e on . H yp py ( p p ) (Gr . hypo beneath

: pyon pus . ) P us in the anterior chamber of

t h e eye .

’ i- - - ot e n e h e . H yp us ( pot nus ) ( Gr . hypo under

tein ein to stretch . ) The S ide of a right

angled triangle opposite the right angle .

’ - - - - — n . o H yp oton ia (h i p o to e ah ) ( Gr . hyp under l = tonos tone . ) D iminished intraocular tension .

’ - - - ee . H ypotonus (h i pot o nus ) . S H ypotonia

’ - - - H yp otony (h i pot o n e ) . S ee H ypotonia .

I D E NT ICA L P O INT S . When the image falls on _ corresponding points on th e retinae of the two

eyes .

’ - - — - L = a . ill a qu eatio n ( il lak w e shun ) . ( illaqueare ~ to ensnare . ) The curing of ingrowing eye

lashes by drawing with a loop .

’ ’ - - - - llumin re ; L . i a Illuminatio n ( il l n min a shun ) . ( f

- oh to light up . ) The lighting up of a place or

1 1 4 LE WIS PO CKE T

in are : eye their order a s follows the cornea ,

' m h the aqueous hu or , t e crys tallin e

lens , and vitreous humor, Di fferent indices of refraction would mean different den

sities .

' - - Indu ction ( in duk shun) . ( P hysic s ) Th e prop

ert y by which one body, having electrical or

magnetic force , induces it in another body with

out direct contact .

’ e t n - - - L l n r ia ( i er shi a ) . ( . idleness . ) ( P hysic s ) That property of matter by which it t ends when

at rest to remain so , and when in motion to

continue in motion , and in the same straight line or direction unless acted upon by some

external force .

’ - - - t ih fil . L fil r re i nfil rat io n ( tra shun) ( . in , and t a

to filter . ) The act or process of infiltrating a

fluid into the cellular tissue .

Infinit e Di s ta n c e. When rays of light proceed from a distance of twenty feet or more they are

considered parallel . and are said to come from

infinity .

’ - — - fl m e m t fl L . in am ar I n fla m a io n ( ln a m ma S hun ) . (

to burn . ) A diseased condition characterized by

m t i. . ra a c redness , pain , heat and swelling T u i ,

that which follows a wound or injury .

’ - - fl ectere l n fl ect i on (l n fl ek shun ) . ( L . in in t to bend . ) The act of bending inward or hat

state of being bent inward .

in f ra . A prefix denoting a position below the

part denoted by the word to which it is j oined .

in f ra ducti on , Deors umv e rge n c e . The act or power

of turning one eye downward from its fellow . O PHTHALM IC DI C TIO NARY 1 1 5

’ f ra o rb ta in - - r - - l n i l ( fra o b i tal ) . S ituated beneath

th e orbit .

’ n e rva t ih - - - In ion ( nerv a shun ) . ( L . in not

r : nervus nerve . ) The sending of nervous s timu

lus or power to an organ through its nerves .

' e rvat e in - -e i nn ( nerv t) . To supply with nerves ; to give nervous stimulus to .

IN S T R UM ENT S A N D T H EI R US E S

b s c e . Am lyo o p An instrument to stimulate , exerci s e and dev e lop the fusion faculty in stra

b is mus . , or squinting patients

rT s t Colo e A set of worsteds , t consisting of various shades and tin s , for test

ing color blindness .

’ F t - - - o c im e e r ( fo sim e ter ) . An instrument for measuring the focal lengths of lenses or com

bina tion of lenses . t m t K era o e e r. S ee O phthalmometer .

Kryp tos c op e . An instrument used for testing n ru s train in ophthalmic lenses . With this i s t ment strain can be detected in fused ( k ryp tok ) l enses or when the screw holding a lens in its f rame i s too tight .

L t es t O t a p om et e r. An instrument combining th e advantages of a fixed and revolving cell 1 1 6 L E W I S P O C KE T

P trial frame , S tevens horometer , Rotary P rism

and M addox Multiple R od .

’ M m t r m - - yo e e ( y o meter) . An instrum ent for diagnosing and correcting muscular insufficiency

at the near point of vision .

O phtha l mos co p e . An instrument with which

the interior of the eye may b e examined . A l so the dioptric and pathological states may be de

termin ed . There are many different kinds of L O phthalmoscopes ; for instance , the oring i s

a small hand affair , which contains a mirror

- and a number of lenses ; the self luminous , by

D Z n e e g , also a hand instrument ; and the com

binea ophthalmoscope and retinoscope , a com b in ed instrument for indirect ophthalmoscopy

and for retinoscopy . This is a large machine

which stands on a table .

O p hth a lmo met er or K e ratom et e r. An in s tru ment for determining the amount and axis of

corneal astigmatism , an obj ective test .

O phth a lmom et ros co p e . An ophthalmoscope w ith an attachment for measuring the refra c

tion of the eye .

P e rim et e r. An instrument for measuring the

vi sual field .

P unct umet e r. A simple instrument for deter

mining the far point and the near point . there

fore the amount of hypermetropia , myopia , or f presbyopia . It also indicates the age o the

patient .

S a v a ge Mo n o cul a r .P ho romet e r a n d Cyc io

P ho romet e r. Two instruments which together make a complete appliance for measuring all of

the muscles of the eye . s an d S k i a s co p e . A fram e with a serie of plus

L E TY I S PO C KE T

’ - - k - l ri d e ct om e ( ir id e tom ) . An instrument used in cutting the iris in iridectomy

- fi ir de t ze - id ek t mo iz i c omi ( ir o e ) . To cut away a

part of the iris .

’ t - i - k - - dec d e m . Iri omy ( ir to y ) ( Gr. iris ek tome

excision . ) The operation for removing a piece from the iris for the relief of tension of the

eyeball in the case of glaucoma , thus producing

an artificial pupil .

’ ir d e s ( - id - en - l - i en c l isi ir c i sis ) . ( Gr . iri s en kl eio

to enclose . ) An operation for displacing the

its pupil from natural position , brought about by drawing the iris into a wound made near th e

periphery of the cornea , and ca us mg it to b e

come adherent there .

’ - id - er- - - r — d e r e . G i ri em i a ( ir mi ah ) ( . iri s i eremia

to deprive . ) D efect or imperfect condition of

the iris .

’ - - z P u . Iri des ( ir id e ) . l ral of iris

’ - - - i Gr . id e S s . l ri des i s ( ir ) ( iri s desis to bind . ) S trangulation of a part of the iris to form an

artificial pupil . z V ra in b ow . I rid es c ent i s ion . ( Gr . iris ) That con dition in which variously hued borders are seen

surrounding arti ficial light .

’ - - k P . I ri di c ( i rid i ) . ertaining to the iris

’ ’ - - - - - iri do a v ul s ion ( ir i doh a vul shun ) . A term a p plied to the total removal of the iris when it is

completely torn from its periphery .

’ - - r I i . Iri do c e l e ( i rid o ( G . r s kele hernia )

H ernial protrusion of a slip of the iris .

’ - - - k - - i - I n fl amma l ridoc horo idit is ( ir id o o roid ti s ) .

tion of the iris and choroid . O PHTHALM IC DI C TIO NARY 1 9

’ l ri i i - - - - - doc n es s ( ir id o sin e sis ) . The movement of

th e iri s in contracting and expanding .

’ r d c t - id - - - - c s o s c . r k k l I i o y li i (ir y li tis ) ( G . iris + y os

circle itis inflammation . ) Inflammation b ‘ of the iri s and ciliary ody .

’ r i i dod es is . That condition in which a loop of iris ut is drawn o , and strangulated by a fine ligature tied around it over the incision ; the little loop

- soon drops off , and the result i s a pear shaped

pupil , with its broad end toward the center .

’ r d d a s -id - o- - a - - r dia l i i o i ly i s ( ir di l y s is ) . ( G . iri s y i = S s s separation . ) eparation of th e iris from

the ciliary body .

’ r n - i - - - - n I ido do es i s ( ir d o do n e sis ) . ( Gr . iris do eo

agitation . ) Trembling condition of the iris .

’ r d - - - I i on c us ( ir id on kus ) . ( Gr. iris onkos

swelling . ) A tumor or swelling of the iri s .

’ ’ l ri ------r G . dop e rip ha c it is ( ir id o per i ia S i tis ) . ( iris m peri around p h ak os lens . ) I n fl am a

'

tion of the capsule of the lens of the eye .

’ - - - - - l ri l n i id ui . r . dop a a ( ir o pla ah ) ( G . wandering )

Trembling of the iris ; iridodonesis .

’ - - - - Gr. l e e I ri dop l egi a ( ir id o p l e g i ah ) . ( iris p g

stroke . ) P aralysis of the iris . Without defect

th e of accommodation , it usually affects only

action to light , reflex iridoplegia , the associated

action remaining . It occurs as a very early

symptom in locomotor ataxia , sometimes with

out any other symptoms of that disease , and

should always lead to full investigation . It is , probably due to degeneration in that part of the nucleus of t h e third nerve which pres ides

over the reflex action of the pupil . 1 2 0 L E W' I S PO C KE T

’ l ridorrh ex i - id - r- rh x - s ( ir o e is ) . ( Gr . iris rhexis

. R rupture ) upture of the iris . Tearing away of

the margin of the iris . d ’ r s c e r t . Gr. I i o l o omy ( iris tome incision . ) P uncture of the sclerotic and of the edge of the

iris .

’ d t - id- ot - o-m Gr iris m l ri o omy ( ir y ) ( . + to e

incision . ) The operation whereby an artificial pupil is formed by the natural gaping of a sim

ple inci sion in the iris . iridotomy is most use

. ful when the iri s has become tightly drawn toward the operation scar by iritis occurring

after a cataract has b een removed .

r s . Gr . m I i ( . rainbow ) S o called fro its resem

th e bling rainbow in its many colors . The

membrane , stretched vertically in the anterior

part of the eye , in the aqueous humor , in which it forms a flat circular partition separating the

anterior from the posterior chamber . It i s the n anterior part of the seco d tunic , and is per

fora ted b y a circular opening czalled the pupil , which is constantly varying in s i e , owing to the

contractions Of its two sets of muscles . Its posterior surface is covered with a black coat of pigment which continues backward over the

ciliary body and choroid . The greater circum f erence of the iris is adherent to the ciliary body and to the sclerotic by the ciliary liga

L P tin tum . ment . ( igamentum ec a Irides ) Its

arteries are from the long ciliary arteries , which

form two circles , one broad near its circumfer

ence , the other small and seated around the

circumference of the pupil . Its veins empty into the long ciliary veins and into the Vena t Vortis os ea . The pupil is con racted by the cir

1 2 2 LE W I S PO C KE T

’ s s c e e i- - - z l o l s ( sos e l e ) . ( Gr. i sos equal s k el os

leg . ) H aving two sides equal .

C t r - = s c tro I k . r I o o p i ( p ) ( G . isos equal trope a

turning . ) E qual in refrac tive powe r .

’ J A G E R S T E S T T Y P E . The standard type for

close reading , a hand chart .

’ J r s S t t off oy ym p om . That condition which exi s s when patient suddenly turns his eyes upward and there is absence of facial contraction ; seen

in exophthalmic goiter .

’ - - - KAT AP HO RIA ( kat a phor ia) . ( Gr . kata

- - z t down l p h oria ten din g . ) That condi ion in which the eyes turn downward when the ex

s trin s ic muscles are in a state of rest . S teven gives 5 0° for the maximum depression of nor ma l eyes

' - - - - K e ra ta l gi a ( ker at al je ah ) . ( Gr . keras horn

a l gos pain . ) That condition in which there i s

pain in the cornea .

’ t - a t- k - - - K e ra tec a s i a (ker e ta si ah ) . ( Gr. keras

horn ektasis extrusion . ) That condition in

which the cornea protrudes .

’ - - - t i . r K e ra iti s (ker at tis ) ( G . keras horn i ti s

inflammation . ) Inflammation of the cornea .

’ - - - = —1 t a t o . r k r rn K e ra o cel e (ker cele ) ( G . e a s h o z k el e h ern ia . ) Corneal protrusion of Desce

’ m et s Membrane .

' n - a t- -k - = K e ra to co us (ker o o nus ) . ( Gr. kera s horn O PHTHALM IC DIC TIO NARY 1 2 3

konos cone . ) That condition in which there

is a conical cornea .

’ e ra t bus -at- - - K oglo (ker o glo bus ) . ( Gr . keras h orn L = lob us b a ll . + . g ) A globular p rotru

sion of the cornea .

’ e rat e c s s - a t- o- - k - K oh l o i ( ker hel o sis ) . ( Gr. keras

horn helkosi s ulceration . ) That condition

wherein there is ulceration of the cornea .

’ e a t r t . K r oi i i s (Gr . keras horn itis in fl a m

mation . ) That condition wherein the cornea

and iris are inflamed . m K e ra to a . (Gr . keras horn oma tumor . )

- A horn like tumor or swelling .

’ r ------r K e atom a l a c i a (ker at o ma la she ah ) . ( G . keras

horn malakia softness . ) S oftening of

the cornea .

’ t - - m K e ra om e (ker at o ) . A knife for incising the

cornea .

’ - - - - r K e ra tomete r (ker at om e ter ) . ( G . keras horn — i metron measure . ) An instrument used for

measuring the cornea . It is commonly called

th e O phthalmom eter , of which there are several

different makes .

’ ’ - - - - M K eratomet ry ( ker a t om e try ) . easurement of

corneal curves .

- - - K e ra tomyc o s i s ( ker at o my ( Gr. keras F horn ( cornea ) mykes fungus . ) ungous

disease of the cornea .

’ - — - - k r = h orn k Gr . e a s K e ra to n yx is ( e r at o nik sis ) .

P t . nyxis a pricking . ) unc ure of the cornea

’ - - - - t t Gr. K e ra to p l as ty (ker a o plas y ) . ( keras horn z" P p l a s s o I form . ) lastic surgery of the

cornea . 1 2 4 LE W I S PO CKE T

’ e ra t s c er t - - - k - - K o l i i s ( ker a to s l e ri tis ) . (Gr . kera s

- horn sclera i itis . ) Inflammation of both

cornea and sclera .

’ e ra t s - - - k r = r c e a t o . r e a s h o n K o o p (ker scope ) ( G .

s k o eo = I p examine. ) Instrument for exam

ining the cornea .

’ - - - - K e ratos c o p y (ker at os ko p e ) . E xamination of

the cornea with a keratoscope . S kiascopy .

’ k - - - k = r t m r . r h rn K e ec o y ( e rek to me ) . ( G e a s o + = ectome excis ion . ) R emoval of part of the

cornea .

m t . n e K ilo e e r O thousand meters .

’ k - - - — Gr K op io p ia or Co p io p i a ( o pee oh pee ah ) . ( .

k . op os fatigue ops eye . ) S ee Asthenopia

’ k - - - - Korectomia or Corect omia ( o rek to mee ah ) .

x t m . ( Gr. kore pupil e o e excision ) The operation for artificial pupil by r e moval of a

part of the iris .

- - fi n K k h . orectop ia ( kor e to p e a ) ( Gr . kore pupil th ektop os out of place . ) D isplacement of e

pupil .

' - - - : k k . Gr Ko ros co py ( o ros o pee ) ( . kore pupil = k R . s op eo I view . ) S ee etinoscopy

K k L r a : a d n r to . c t . yp . ( yp vault ; a hi de p lace ) _ The name applied to a bifocal lens made by fusing two pieces of glass of different densi ty

together , so as to become one integral piece

with no visible line of de marcation .

’ - - m = a LAC H RY MA L (lak rim al ) . ( L . l acri a

tear . ) P ertaining to tears

La c r a t h ym l A p p a ra u s . Consists of the lachrymal

1 2 6 LE W I S PO C KE T

th e eyes turn to the left when the extrinsic

muscles are in a state of rest .

’ L t - f - - a go p h halm us ( lag o thal mus ) . That condition in which it is impossible to close th e eyes;

’ - - 2 im . L el . L d . a m e ll a ( lam ah ) ( . of lamina plate )

L . A thin plate or scale . am ina

’ - - L ln . L . a mina ( lam a ) ( . a plate A layer con

sisting of a flat , thin membrane .

’ ’ ' - - - - L m l min , a a r b r s a a r s a L . in C i o a ( crib o ) . ( a ” - plate cribrum sieve like . ) The perforated area I n the sclerotic of th e eye through which

' th e to optic nerve fibers pass form the retina .

m ’ La a F . L in u s c a ( . a plate fus cus brown . )

The outside layer of the choroid .

La d t E d m d M D. n ol , un , . O phthalmologist , born in S z Aaran , wit erland , in 1 8 4 6 ; pursued his p rofes

s ion a l t studies in the universi ies of H eidelberg , V ienna , B erlin , U trecht and Z urich , graduating from the latter in 1 8 6 9 ; then worked for more than a year as H orner ’ s assistant in the Zurich clinic for eye diseases ; in 1 8 74 he establi shed

n himself in P ari s a s an ophthalmologist . H is l v es tig a tion s in his S pecialty have been distin g uis h ed by their originality? Among his works “ ” “ h th l are O n the R etina , A Manual of O p a

mos co F E G er published in rench . nglish , p y , “ ma n and S panish ; The R efraction and Aecom

modation of the E ye .

’ - L . a p s us (lap sus ) The dropping of the upper lid , produced by a paralysis of th e levator palpebra

P i . muscle . S ynonym , tos s

« La s h es . The name given to the hairs of the eye

lids . O PHTHALM IC DI C TI O NARY 1 2 7

’ L t e n t - z a . L . a r (la tent ) ( l te e to be concealed . )

That which i s not apparent or manifest . S e e

H ypermetropia .

La y er. A stratum having a certain amount of

thickness and serving the purpose of a covering .

’ ’ Leb e r s D L - h s ea s e a . i ( erz ) ( Theodor L eber , Ger O man phthalmologist , Atrophy of the

optic nerve , which i s hereditary .

’ L m l - e a e . ( ma ) The dry , hard , yellowish incrusta

tions which collect in the inner canthus . “ L e n s . ( L . a The term lens was fir s t applied to any transparent refracting body

on a ccoun t which had two spherical surfaces , _ of its resemblance to a vegetable known as a

. n lentil A lens is a transparent substance , crow

or fl int glass chiefly, ground with regular curva

ture on one or both of its opposite sides , but not t parallel to each other , through which an obj ezc may appear to be increased or decreased in si e , and may have either convex or concave spher f i ical or cylindrical sur aces . Th ere are S x vari eties of spherical lenses— three plus and three minus— a l l of which can be made the same d iop

tric power , the only difference being in the P shape of the lens . lus or positive lenses are M thickest in th e center . inus or negative lenses

‘

are thinnest at their centers . A plus sphere will refract the same in a ll its m eridians and con

verge parallel rays of light to a point of focus . while a minus sph ere will diverge parallel rays

from a point . The different forms of plus and minus spherical lenses are here represented A line passing through the optical center a t right angles to the surfaces of these lenses i s 1 2 8 LE W I S PO C KE T

a not refracted , and is known as the princip l

axis , while all other rays undergo more or less

refraction . A secondary axis is any line which

. P a n o x P a D . o n n o o n a v . A l C v e . l C c e i o . x E i n a c n . c o c v e . B B v e . B

C . P ri e s c o i n x P e ris c o ic C o n c a v e . p c C o v e . F . p

crosses th e principal axis a t the optical center

r of a lens . It is not a straight line , but a e

fracted one , and on emerging takes a direction parallel to that which it would h ave pursued ‘

had it not been interrupted by the lens . A c h ro

a t L m i c . , a lens composed of two pieces , one of crown and the other of fl int glass ; the former

one b eing plus and the latter minus , and only f f f hal as strong in its re ractive power , but o

equal dispers ive power , and overcomes ch ro

t L. I matic aberration . A p l a n a i c S on the order of th e achromatic lens , except that th e minus is

divided and placed half on each side of the plus . In thi s way not only the chromatic but the

spherical aberration i s overcome , and a perfect

- n lens formed . They are used for high power i

m n B . t tru ca L. m s e s e ts . ifo l ( see B ifocal ) Co p o i

L . , a lens having three features , namely , S pher

. d r ca L . ical , cylindrical , and prismatic C ylin i l , a lens with refractive power in all meridians

1 3 0 L E W IS PO C KE T

T o ri c Le n s es . The word toric was taken from o the w rd torus , which means in architecture th e large semicircular molding used in the bases of

columns , and the term i s applied to a len s h av

ing curvature i n all meridians , but of different

amounts , on the sam e side of the lens with its meridians of greatest and least curvature at

' right angle s to each other . The meridian of

least curvature i s known as the base curve ,

while the other side of the lens will be plano , a concave or a convex sphere ; but usually made

concave . To give an idea of the appearance and proper

uses of such lenses , I will put up a prescription fiv .for one of the e subdivisions of ametropia

which can be corrected by lenses in toric form .

This can best b e explained by diagrams . This prescription will be for compound hyper

op ic astigmatism 3 . s p h 2 . cyl . ax . 90.

This lens when ground must refract plus‘ three dioptries in the ninetieth and plus five dioptries in the one hundred and eighti eth m e

ridian s , independent of its shape .

B ut in order to get a deep periscopic effect ,

the advantage of which I will explain later , sup pose we grind one side of the lens thus : O PHTHALM IC DIC TIO NARY 1 3 1

The difference between the curva tures in th e two meridians gives us the desired value of th e

cylinder , and on the other side we will grind a t m inus hree sphere , which will neutralize plus

three from all meridians , leaving the lens with

the required strength . In this lens you get a plus sphere and a plus cylinder , and at the same i time , f a cement scale is required , it can be placed next to the eye .

When a toric lens is desired , it is not n eces sary f or the refractionist to m ention the curva turef F or the sake of S implicity, just write the word toric ” beneath the description of the lenses in your prescription . Then write the pre scription in the usual way . Toric lenses are more expensive than the old form of lenses , but on account of their superior

m n ' m re ity they are co i g o into general use .

In the first place , they allow a greatly en l a rg ed field of vision , by allowing the patient to roll the eye and at the same time see through

the edges of his lens .

With lenses of the ordinary type , when an eye turns it looks obliquely through them and f obtains a prismatic e fect that is not desired , causing the image to b e more or less distorted

on the retina , and at the sam e tim e the patient 1 3 2 LE W I S P O C KE T

i s bothered with reflection from the back of the

lenses of obj ects on the S ide . With deep peri scopic lenses the curve coincides approximately

with the arc formed by the eye in turning , and

the eye i s looking much more directly through the lens and obtains a much larger field o f

vision without the extra prismatic effect . The diagram s show the shape of the two

n ki ds of lenses from the same prescription ,

2 1 . s p h . C cyl . ax 90.

Again , the edges of the lenses com e nearer to

’ the face, thus adding to the patient s appear

ance . The result of a lens of this description i s

freedom and comfort to the wearer , so much so

that the extra cost should not be considered .

When a cement bifocal is required , the toric

‘

side should always be plus , so that a minus sphere will be next to the eye on which the

scale may be cemented .

2 L . s . Le n s C a p ul e ( a lentile dim of capsa box ) . t A transparent , highly elas ic , and brittle mem

brane which encloses the crystalline lens . It rests in a depression of the vitreous body just

behind the iris , and is held in position by the

suspensory ligaments .

’ - - - = . l n Le nt i co n u s (len tik o nus ) . ( L e s + con us

1 3 2 L E YVI S PO C KE T

i s bothered with reflection from th e back of the

lenses of obj ects on the side . With deep peri scopic lenses the curve coincides approximately r with the a e formed by the eye in turning , and

the eye is looking much more directly through the lens and obtains a much larger field of

vision without the extra prismatic effect . The diagrams show the S hape of the two

n ki ds of lenses from the same prescription ,

2 1 . 9 s p h . C cyl . ax 0.

Again , the edges of the lenses com e nearer to

’ the face , thus adding to the patient s appear

ance . The result of a lens of this description i s

freedom and comfort to the wearer , so much so

that the extra cost should not be considered . t When a cement b ifocal is required , the oric

'

side should always b e plus , so that a minu s

sphere will be next to the eye , on which the

scale may b e cemented .

L . . Lens C a ps ul e ( a lentile dim of capsa box ) .

A transparent , highly elastic , and brittle mem

brane which encloses the cryst alline lens . I t rests in a depression of the vitreous body just

behind the iris , and is held in position by the

suspensory ligaments .

' - - — = . n Le nti conu s (len tik o nus ) . ( L l e s + con us O PHTHALM IC D IC TI O NARY 1 3 3

cone . ) E xaggerated curvature of the crystalline

lens .

2 L L . e n ti c ular ( lenticula a lentile ) . R esembling

L - a lentil . ens shaped ; pertai n ing to a lens .

Le t r t t . S n i c ul a A s i gm a i s m ee Astigmatism .

’ L - es l . L l r io n ( e S hun ) ( . oed e e z to injure . ) Any

w . hurt , ound , or local degeneration

' ’ L m - k - e uco a (lew o mah ) . S ee L eukoma .

' Le uk ma -k - k = o ( lew o ma ) . ( Gr . l eu os wh ite . )

White corneal opaci ty . Albugo .

Levat r L o ( . levare to lift ) . E levator ; a muscle

raising a part .

’ ’ Leva to r P a l p e b ra Mus cl e (l e-va -tor pal -pe-bra

’ -l M mus ) . S ee uscles .

’ L a me t - - z ig n ( lig a ment ) . ( L . l igare to bind . ) A f tough band of connective tissue , the purpose o

to con n ect which is . the bones together or sur

a round them as capsule . There are several liga

ments concerned i n the anatomy of the eye .

L ‘ men t P Check igament , Cil ia ry L iga , alpebral L igament , E xternal P al pebral L igament , Inter P L L L nal alpebral igament , ockwood igament , S uspensory L igament or Zone of Z inn , L iga

m ent of Z inn . The C ili a ry L . , or circl e (annulus n albidus ) , is the bond of unio between the ex

ternal and middle tunics of the eyeball , and

a t serves to connect the cornea and sclerotic , th their line of junction , with e iris and external

layer of the choroid . It i s also the point to which the ciliary nerves and vessels proceed

previously to their d istribution , and it receives the anterior ciliary arteries through t h e anterior a margin of the sclerotic . A minut e vascul r 1 3 -1 LE W I S PO C KE T

canal is situated Within th e ciliary ligament ,

th e t called ciliary canal , or the Canal of F on ana ,

f ts k . rom i discoverer . Ch ec L , the fibrous bands attached by one end to th e anterior wall of th e O rb it and by the other to the tendons of th e

recti muscles . Those on the inner side are l t called the internal check igaments, and hose

o n or e tem l e th e the outer p side . external check

ligaments . The action of these ligaments is a

normal one . They prevent or retard overaction L kw of the abductors or adductors . o c oo d L . , a band of orbital tissue in th e anterior part of

- th e orbit , where it forms a hammock like band

attached at. one end to the l a ch rimal and at the I t l other to the malar bone. s broader centra part passes below the eyeball over th e Capsule

T h e L of Tenon . e P a l p bra l . joins the cartilage of the lids to the orbit the same as the tarsal

E t r P L . t th e ligament . The x e na l a l p eb ra l uni es

lid to the outer edges of the orb it . The Int erna l

P r L a l p e b a l . covers an area including the upper

maxilla to the inner margin of the l id . The

S s r L . Z Z u s p en o y , or one of inn , surrounds the crystalline lens a n d holds it in place within the

circle of th e muscle of accommodation .

Liga m ent of Z inn . A circular ligament which is h attached to th e bone at t e optic foramen , from

which arise the four recti muscles .

Liga m entum P ect in atum . The ligaments which

pass from the base of the iris to the cornea .

’

Through its m eshes pass F ontana s spaces .

: L L t L l ux l i h t . igh ( . g ) ight is that physical t force which , af er entering the eye and acting ‘ the upon the sensitive elements of retina , ex

1 3 6 L E W I S PO C KE T

D ifferent colored light has different wave

length . R ed has the longest and violet the

shortest waves . It will be noted that violet must travel much faster than red in order to

- travel with it through space . The main primary u colors are red , yellow and bl e ; the others ,

a re orange , green , indigo and violet , secondary “ or binary colors . In moving colored objects so that their image moves from the macula to th e periphery of the

retina , colors grow dim ; green is lost first , then

red , yellow and blue last . Color blindness is l generally congenita , but may be acquired by .

changes in the retina , p articularly in atrophy

of the optic nerve . F rom an optical s tandpoint there are two

theorie s of the way in which light travels ,

namely , rays and waves .

Ra l l l A y i s the sma est visible ine of light . A Be a m i s a col lection or bundle of parallel

rays . A P e nci l i s a number of converging or diverg

in g rays . Rays emanating f rom an illuminating or an illuminated point always d iverge ; i n nature

there are no converging rays , neither are there l any abso utely parallel , but those proceeding from a point 2 0 feet or farther away are so nearly so that th e difi eren ce can only b e mathe

m i a ll a t c y expressed , and for th e purposes of t op ics are con s idered as parallel . According to

th e calculations of astronomers , light moves at the rate of about miles in a second ;

according to this , it requires about nine minutes f or the waves of light from the sun to reach th e O PH T HALM IC DI C TIO NARY 1 3 7

earth , and those from the nearest fixed star are

fi vé years on their journey before they reach us . F rom an optical standpoint we now refer to “ ” the W ave Theory , and in order to do thi s it will be necessary to draw somewhat on one ’ s

imagination . Y ou have ofttimes noticed when a stone is dropped into a calm pond of water it throws forth circular waves in all directions . The first or nearest wave to th e stone will have

the shortest radius of curvature , or , in other

W . ords , the greatest strength of curvature As this wave spreads it will decrease in curvature 2 2 0 until it has traveled 0 feet . Beyond feet the

waves are considered plane , meaning by this

that , when on account of the pupil of the eye

being about an eighth of an inch in diameter , we cut from a wave of light that has traveled

f - 2 0 eet a piece one eighth of an inch long , that

is , the amount that would enter the eye , it would have so slight a curve that it is con s id \ ered to have none . Thi s i s known as a plane

wave . The word minus denotes les s ; the farther the

wave travels from its center , the less its curva ture ; therefore all waves that are going from a point we consider m inus , and for the sake of simplicity we must compare the wave s of light with the waves of water , and instead of drO p ping the stone we will light a candle that will

throw off waves in all directions . When a wave has traveled one -half inch from a point it has

a curve of minus 8 0, because it has a radius of

- curvature of one eightieth meter . N ow , as the

one and same wave moves on , it lose s its curva

ture ; thus , when it has travele d one inch from 1 3 8 LE W I S PO C KE T

i 4 0 its center its curvature is less , or m nus ; 2 0 i and at two inches , minus ; three nches , 1 0 m inus 1 3 ; f our inches , minus ; five inches , 2 m inus 8 ; twenty inches , minus ; forty inches , 0 minus 1 ; eight y inches , minus . 5 ( these figures h are the fractional part of a meter , whic the c distance represents ) ; twenty feet , no urve , or

plane wave . Now , if one will stop to think , he will observe these figures compare with the focal length of lenses in the trial case ; that

is to s a y , a wave that has traveled forty inches 1 from a point i s known as a m inus , and a

- 1 dioptry lens has a focal length of forty inche s . A wave that has traveled twenty inches from a 2 2 point i s known as a m inus , while a dioptry

F or in lens would focus at twenty i“nches . e e stance , you may ask yours lf , What would b the curvature of a wave of light that has a ” radius of thirteen inches ? Y ou would at once “ think of the dioptric number of the lens that

“

would focus at thirteen inches . This would be

3 - ou w ould a dioptry . Then y e say that the curve

is minus 3 , if it is gomg from a point , but I f

‘

going to a point , plus 3 . Y ou will notice that in referring to a meter it i s S poken of as forty

inches . There is a difference between the two ,

yet it i s near enough for our purpose , and saves the trouble and inconvenience of working with

fractions ; so far , we have spoken of the minus

wave , as all waves in nature are minus ; in order to have a plus wave we must use arti

n oia l means , and will work out the following example : P lace a lighted candle forty inches from a plus 3 sphere ; considering the candle the point from which the light comes ; the wave

4 at M i + . C op try rror.

1 4 4 L E W I S P O CKE T

' L de - - e = o a s d r. a d s h g (log a ees ) . ( G log t e whites

of the eyes . ) The first coat or tunic of the eye .

’ Lo a r t - - i = g i hm ( log a r th m) . (Gr . logos w ord a rith m = os number . ) The exponent of the power to which a number called the base ( in

th e common system , 1 0) must be raised to pro

duce a number . L im ’ mi o o ht h a l a . p Contagious ophthalmia .

’ L n it d e - i- L o g u ( lon j tud ) . ( . longus long . ) The

angle at the pole between two meridians , one of w P M hich , the rime eridian , passes through som e conventional point and from which the angle i s

measured .

- L o S t ed es s . S ee ng i gh n H yperopia .

Lorgn ette ( lorn Double eye - glasses attached t o a handle . Thi s term is often applied to

- opera glasses .

L t . ou ch e t es A kind of O paque glasses in which ,

for each eye , there is a small opening which makes it impossible to look in any other way

than through this opening .

’ - - - Lox o ht ha imos . Gr l oxos p ( lok sof thal mus ) ( . That condition

in which the eye is turned from parallelism .

( S trabismus ; H eterotropia . ) L L u ci d ( . lucere to shine ) . Clear , distinct .

’ L - - - u c ifu ga l (l n sif u gal ) . That condition which

exists where a person avoids bright light .

Lumino us Bodi es . Those sources of direct light ,

as the sun , a lighted candle , etc . P i Lumino us u p il . The appearance of the pup l

under observation with the retinoscope .

’ x - - L l xare zzto Lu ation ( luk s a shun ) of Lens ( . u O PHTHALM IC DI C TIO NARY 1 4 5

dislocate ) . That condition where the crystalline

lens i s dislocated . L = m h L . . y p ( lympha water ) A transparent , slightly yellow liquid which fills the lymphatic

vessels . It is occasionally rose color from the

presence of blood corpuscles , and is often

. S t opalescent from particles of fat L. ys em is a collective term for the lymphatic glands and S l v e s e s .

’ L - - k P m t i . of y p ha i c (lim fat ) ertaining to , the

nature of, containing , or conveying lymph .

’ R - - - M AC O P S IA ( mak rop s i ah ) . ( Gr. makros large That condition of an eye in which obj ects appear larger than they

really are .

’ M - - - a c r s c c m k r l . o opi ( a o scop o) . Gr makros

large skop eo I view . ) That which may b e

seen with the naked eye .

’ ’ M L - - - a cuia utca ( mak yu lah lew t e ah ) . (L . a sp ot

lutea yellow . ) The small yellow S pot of

the retina which lies directly in the visual axis . 4 It is about mm . to the temporal side of the

center of the optic disc , on the horizontal me

n . ridia , and is less than 2 m m in diameter . A

depression in its center , fovea centralis , i s the

most sensitive point of vi sion .

’ - - - Ma da ros i s ( mad ar o sis ) . ( Gr . bald . ) T hat condition in wh ich the eyelashes are perma

n en tly destroyed .

Ma dd x Rod E E M o ( rnest . addox , E nglish op h th al

mologis t) . An opaque disc with a slit through

- the center . O ver thi s slit is placed a glass rod 1 4 6 L E I VI S PO C KE T

or cylinder . In looking through this rod at a small round light it causes the light to look like

M a d d o x R od .

a long streak . This rod with a re glass disc over the other eye is use d for testi n g muscular f imb a l imbalance . Be ore testing for muscular

ance correct all errors of refraction .

’ - - - i- Ma di s te riu m ( mad i s ter um ) . An instrument

used f or removing the eyelashes . t t Ma gn et O p e ra ion . A me hod used for removing particle s of iron and steel embedded within the

t . tissue of the eye , by means of a magne

' - - in Ma gnify ( mag mi fy ) . To render an apparent crease in the S ize of an object above that seen

in emmetropia .

’ - - - k = t M i . m l ia a a ia c a ( mal a se ah ) . ( Gr a a sof

ness . ) M orbid softening of tissue .

' ------Ma la c ocata ra cta ( mal a k o kat ar ak tah ) . A soft cataract which form s in the crystalline lens of

a person under the fortieth year . This form of

cataract i s usually the result of injury .

1 4 8 LE \ V I S PO CKE T

M ed a 11 i n lin e, . A line perpendicular to and b i s ectin g the di stance between the centers of

rotation of the eyes .

Med i um . Intervening body or quantity . The

dioptric media of the eye consist of the cornea ,

aqueous humor , crystalline lens , and vitreous

humor .

’ Me a oc ea -al - o- -n e- g l orn ( meg kor ah ) . ( Gr. megas = large . ) That condition in which there i s

bulging of the cornea .

' Me a a - al -o - - r g lo p i ( meg pi ah ) . ( G . megas great

op s eye . ) S ee Macropsia .

' Me a s -a i- o - - Gr g lo p ia ( meg p si ah ) . ( . megas great i op s s vision . ) That condition of the eye in which objects appear larger than they really

are .

' Me a s c e s k o eo g lo o p ( Gr . megas great p I

' l ar ma n if in view ) . A g e g y g lens .

’ Me a s c e - a -s k o e g o p ( meg p ) . A microscope for ex min in a g large obj ects .

’ Me t a s - of- - go ph h lmu (meg thal mus ) . ( Gr . megas i great op h th al mos eye . ) That condition in

which the part of eye is abnormally large .

’ Mei bomi a n Gl a nds ( mi - b o -m e - an ; after M eib o

n d s mius , the discoverer ) . A variety of gla l

which are embedded in the tarsal cartilages . There are from thirty to forty in the upper lid

and from twenty to thirty in the lower lid . Their ducts open upon the free margin of th e

lids . These glands secrete a sebaceous , oily fluid which assi sts in lubricating the lids as

they glide over the eyeball , and also prevents the lids from sticking together when we have

them closed . Another function is , that as the O PHTHALM I C DI C TIO NARY 1 4 9

margins of the lid s are kept oily at all times the

. tears do not flow over the m so easily Thi s oily , substance also mixes with the tears and assists ’

N T M O F D A A O Y LI S .

N o 1 m ia a r i a ri . . M e i o b n G l n d s . N o. 5 . O b c ul s M us c l e s . N o . 2 . P un c t a L a c h r m a i a r m a a n d s y l a . N o . 6 . L c h y l G l .

N os . 3 a n d L a r 4 . c h a a n a ym l C l s .

in preventing friction between the eyeball and

lids , and at the sam e time prevents the cornea

from becoming dry so quickly . Also known as

tarsal glands . S ee Chalazion ;

’ Me mel a s = l k e l a nin ( Gr. b a c ) . A dark pigm nt

from choroid , hair , and other dark tissues . = M . el a s m a ( Gr . melas black ) . Melanoderma ;

morbid cutaneous discoloration .

’ ’ Mel a s m a P a l p eb ra ru m (mel -as - ma pal - p e - bra

rum ) . A d iscoloration of the eyelid , which m occurs frequently in pregnant wo en . M em b ra na C a p s ul a ri s . That portion of the ar teria centralis which forms a vascular network

and coats the posterior surface of the lens . 1 5 0 LE W I S PO C KE T

’ M m - - e b ra na P u p il la ri s ( mem bra na ) . A membrane

covering the pupil of fetal life . This some

times fails to disappear up to time of birth .

’ M - em b ra n e ( mem bran ) . A thin tissue covering

some surface or organ . M m L = e b r n t t t n i r . a e Ni c i a ing ( . ict ta e to wink ) That which is sometimes called the third eye

lid , to be seen in various animals . M k = enis c us ( men ( Gr. men is os cres

' A cent . ) crescent . When applied to a lens , woul d mean that it is more periscopic than

necessary to produce the same refracting power .

’ h i - -t - - Me n otyp los s ( men o yf lo sis ) . A condition of the eye in which there is diminution of vision

during night .

’ - - - M en s uratio n ( men s u ra shun) . Th e science of

measuring .

’ - - - - M e rama uros is ( mer am au ro sis ) . A condition of the eye in which part of the field of vision is

lost ; partial amaurosis .

’ M - - - t e ridi a n ( mer id i a n ) . In optics , any straigh line passing from edge to e dge on the surface

of a lens a n d over its optical center . A merid ian of the cornea is any straight line crossing

its S urface through its anterior pole . A circle

- describes one half of which , or is “

marked on the trial frame . 0 and 1 80 are found

° in the horizontal , 9 0 describes the vertical .

O u - the clock - dial ( astigmatic chart ) they are

numbered from left to right , which must be

remembered when fitting glasses , and on trial

frame from right to left . These figures on trial frame correspond with clock -dial when they

face each other .

315 2 L E I V I S PO C KE T

when in a state of rest , they will be forced to use two m eter angles of convergence in order

to view an object one meter distant . Thi s de scription applies to th e different varieties of

muscular imbalance . M t e e r Le n s . A lens that will focus parallel rays

of light at a distance of one meter . M et ri c C urv e. A curve that has a radius of one M meter ; two , C . has a radius of 2 0 inches .

M et ri c S ys t e m. A decimal system of weights and measures adopted in F rance ( 1 79 5 ) and various

E uropean countries , and gradually coming into

general use for scientific purposes . Ten units o of one denomination marking one unit of th e

next higher . A meter i s equivalent to about

E nglish I nches . Decimal parts of the standard or principal unit are denoted by L atin prefixes ; multiples of

the same , by Greek prefixes .

F rom t h e Lati n F ro m t h e G reek Milli means Myria means Centi means Kilo means D eci m eans H ekto means 1 00 D eka means 1 0 In the tables units in common use are in bold

f a c ed ty p e .

Units of Le ngt h

Standard unit , the Mete r

T a b le

2 1 nt m t m c e e r . 1 0 milli et e rs (mm . ) i e ( cm )

1 0 centim eters 1 decimeter ( dm. )

1 0 decimeters 1 m et e r (m. ) O PHTHALM IC DI C TI O NARY 1 5 3

‘ ‘ 1 0 meters 1 d ekameter ( URL ) 1 0 dekameters 1 h ek ton ieter ( H m ) 1 0 hektometers 4 1 k i lometer ( Km ) 1 0 kilometers 1 my’ riameter ( Mm )

M c r b r - s i o l ep h a i a ah) . ( Gr . mikro

small blepharon ey elid . ) A very narrow

and thin eyelid .

’ Mi - k - c rocorn ia ( mi ro kor (. Gr. mikros n small . ) A small cor ea .

’ - - — - : M ic role n t ia ( m i kro len tiah ) . A very smal l crys

n talli e lens .

Mi r met r E m ll metrO n c o e (Gr . mikros s a

‘ measure ) . An instrument which is used for n d maki g measurements of very small bo ies .

’ M h m m - k r f- - - c r ht a a o h . r i o p l i ( y thal mee a ) ( G . mi

' h th l m s n m kros small op a o eye . ) Ab or ally

small eyes .

’ M - - - k c r s m . ros i o p ia ( y krop see ah ) . ( Gr m i i f h small op s s z sight . ) That condit ion o t e eye in which obj ects appear smaller than they

really should .

’ M - - m i c ro s co p e ( mi kro scope ) . ( Gr . ikros small k s op eo I view . ) An optical instrument

used for examining minute obj ects .

M = - k ra n ion i g ra i n e ( mi (Gr . hemi half i

skull . ) A kind of sickness or nervous head ache usually periodical and confined to the si de ,

of the head .

' - M il k . M . i ron (mi kron ) (Gr . mikros small )

l i n o th part of a meter .

M : ili um ( L . millet seed ) . A small elevation , on

the skin of the eyelid , filled with a grea s y

secretion . 1 5 4 LE W I S PO CKE T

’ M il h a e - p ( mil phae ) . A morbid condition in which

t h e eyelashes. drop out .

’ M l - - i p ho s i s ( mil fo sis ) . That condition in wh ich th e eyebrows as well as th e eyel ashes have f allen out .

' M f -i- ini y ( min fy ) . To render an apparent de crease in the S ize of an object from that seen in

emmetropia .

’ M n ue n d - - = . ) u L min u re . i ( min end ) ( . e to lessen The number from which another num b er is

subtracted .

’ M - ° inu s ( mi nus ) . L ess that from which some thing has been subtracted ; negative ; as a M minus quantity . inus lenses , same as con

cave .

’ M - - s s o r . io i ( mi sis ) . ( G . meiosis a lessening ) E xcessive contraction of the pupil .

’ M t c - - t - i io i ( mi o c ) . Any agent or medicine which

causes th e pupil to contract .

’ M - - ol ec ul e ( mol e kul ) . The smallest particle of

any substance .

’ - - = M . m . L m lli oft ollu s cu ( mol us kum ) ( . o s s ) A

skin disease w ith pulpy tumors , chiefly on the

face , neck , and trunk , due to altered gland

secretion . A small pearly , warty elevation which breaks down in the center and discharges

a cheeselike material . It is said to be con ta gious

’ - - If. Mome n tum ( mo men tum ) . ( momentum mo

tion . ) The quantity of motion in a moving body being always proportioned to the quantity ,

of matter multiplied into the velocity .

- mon os = on e Mon oblep s is ( moh o ( Gr . That condition in which

1 5 6 LE W I S P O C K E T

t hickenin g of the lining membrane , and in

creased secretion of mucus . The mucus may be r t clea or turbid . Any tumor con aining mucus .

’ ' s c a e Vc l it n t es - mus- v - - - Mu a ( cae ol itan tes . L . _ ) ( a flying S mall flo ting bodies , resem

s e t bling ticks , c, , which move about in the field

of vision , but .do not actually cross the fixation

point , and n ever interfere with s ight . They are

e usual ly se n against some bright object . They n m u a s th depend upo in te ch nge in e vitreous ,

which are present in nearly all eyes . They r t th t vary , or seem to vary, g eatly wi h e heal h t t t b and s ate of h e circula ion , ut are of no real

importance . They are mos t a bug dan t and

e troublesome in myopic yes .

L m = r s c e . us cu s a Mu l ( lu . little mouse , f om the m u i rese blance of a m scl e, n contraction to the M movements of a mouse under a cloth) . uscles . ( E ye ) The eyeball is ro tated around its center of rotation by the in d ividual or combined action

‘ s re cti or of six muscle , namely , four straight ,

and th e two oblique ; th e s eventh muscle , l eva l i o u tor pa pebrae , s attached t the pper lid ,

which it raises .

O f the six musc les inserted in to th e eyeball , five take their origin from the apex of the

n d t orbit , while the sixth a S h or est, the inferior

it s u oblique , takes s origin from the perio r max illary bone at th e an terior and na sal side of the

orbit .

n d Int e rn a l Rect us Mus cl e turns the e ye in , a is supplied by the third cran ial or mote r oculi

n erve .

S r or Re t s c e th e e e n d u p e i c us Mu l turn s y up , a O PHTHALM IC DI C TI O NARY 1 5 7

is supplied by the third cranial or motor oculi

nerve .

n f e r or Rect us M us c e I i l turn s the eye down , and is supplied by the third cranial or motor

oculi nerve . I n f e ri o r O bliq ue M us cl e rolls the eye on its w optic axis , dra ing the bottom and back part of the eye in and down while the front moves up

and out , and . is supplied by the third cranial or

motor oculi nerve .

E x . e t M t e rn a l R c us us c l e turns the eye out , and is supplied by the sixth cranial or abducens

nerve . S up e rio r O bliq ue Mus cl e rolls the eye on its

optic axis , turning the back p art of the eye inward and upward while the front part moves u down and out , and is supplied by the fo rth

cranial or patheticus nerve .

M s c e Cili a ry u l s are inside the eyeballs , and are used for accommodating only . They are

'

supplied by the third nerve . O rbi c ul a ri s P a l p e b ra rum M us cl e closes the d li s , and is supplied by the seventh , or facial

nerve . ( O n e of the muscles of expression . ) ‘ t r S u e r r s Leva o r P a l p e b a p io i lifts the lids , and is fed by a branch of the third cranial nerve .

n t r Mus c e - S p hi c e l , which closes the pupil , i s supplied by the third nerve .

M s - t Ra di at i n g u s cl e of the iris , which dila e t t the pupil , are supplied by the sympa he ic

nerve .

’ H o rn e r s Mus cl e . S ee Tensor Tarsi . P a l p eb ra l M us cl es are two involuntary mus i fies , superior and inferior . The super or is p rincipally inserted into th e upper margin of LE W IS PO C KE T

f the tarsal plate . The in erior , found in the

lower lid , interwoven with the fasciculi of the orbicularis palpebrarum .

’ Ri ol a n s M us c l e is the muscular tissue sur rounding the hair follicles and glands of Moll , near th e border of the eyelids .

T e ns o r T a rs i compresses the lachrymal sac S u and the puncta against the eyeball . p .pulls plied by the seventh cranial nerve .

C o rrugato r S up e rc ilii d raws eye b row do wn

1 GO LE W IS PO CKE T

M ll ’ ‘ u e r s Mus c l e . B ands of circul ar fibers sit uated internal to the radiat ing muscles in the

ciliary body . They are sometimes called the M ring muscle of uller . F i be rs of Mulle r are th e radiating fibers which pass through nearly

th e entire thickness of the retina , supporting its f dif erent layers and binding them together . They form at one end the membrana limitans

I n nterna and at the other end the exter a .

M A t s a r s . u cul h eno p i a . S ee Asthenopia

- Mu s c ul a r Imba l a n c e . It is generally a greed by the authorities of today that ametropia is re M sponsible for 9 0 per cent of uscular Imbalance . F or this reason it i s considered advisable to always correct any ametropia that may be pres

ent , and have the patient wear the correction

for at least six weeks . At the end of this time ,

should any muscular imbalance be manifest ,

correct half of the amount . Always test for muscle trouble while the patient i s wearing his o full correction for the ametropia , therwise it

‘

will not be considered a proper test . There are

: . . but few exceptions to this rule e g , when a

prism , base in , will allow you to decrease a

S ee m inus lens or in crease a plus , prescribe it .

H eterophoria and H eterotropia .

f f - - h l - - h In flamma Myc o p ht ha lmia ( mi kof t a mi a ) .

tion of the conjunctiva , caused by a spongy

growth .

’ r - - - il i n My d ri as i s (mid ri as is ) . D atat o of the p upil , caused by the us e of atropine or other mydria t

th . ics , or paralys is of e motor oculi nerve

’ Myd ria tic ( mid -ri - at -I c ) A drug that dilates the

pupil . O PHTHALM IC DI C TIO NARY 1 6 1

’ M oc e a o n m - i-o- - a l -ou r r yi p h l ( y sef ) . ( G . myia fly

k ep h a l e head . ) A small protrusion of the iris

through a perforation of the cornea .

’ M t - i - z r . y i i s ( m i tis ) . ( G mys muscle itis ih fl mm a a tion . n ) Inflammatio of the muscles .

' M d es o s a Gr — yo p i ( . myla fly l op s is sight ) .S ee M uscae Volitantes .

’ M o ra m - - = — o . Gr m m y g p h ( y graph ) ( . ys us cl e l

grapho I register . ) An instrument for record ng the d fferent phases such as the velocity i i , ,

intensity , etc . , of a muscular contraction , with

the aid of a regi stering apparatus .

’ M o ra m - o - r - y g p hy ( y g a phy ) . (Gr. mys muscle

graphe a drawing . ) A descripti on of muscles . of including the study muscular contraction .

w ith the aid of a registering apparatus .

M lo m - l fl - — o e o i Gr. y gy ( y j ) . ( mys muscle l logia

a discourse . ) A description of the muscles m of the hu an body .

’ o o is t m - l - - n e in My l g ( y o o gist ) . O skilled that part

of anatomy which treats of muscles .

’ M m - - e . d yo p ( y ope ) A near sighte person .

' M - - - - Gr m . yo p i a ( y o pi ah ) . ( myo close ops

eye . ) An optical defect of the eye which causes p arallel rays of ‘ light to focus in front of the

retina , with the muscles of accommodation at B rest . It i s also known as rachymetropia and

H ypometropia . A correction ( concave lens ) i s

necessary before normal vision can be obtained . In the ea rly days the G reeks noticed that all

near - sighted persons could see better at a di s

tance by half closing the eyelids ( squinting ) .

hence the name myopia . The eyeball may l l!: LE \ V I S P O CKE T

be too long ( axial ) or the refraction too great , causing the parallel rays to cross and meet the

retina a s d ivergent rays , which form a circle of f di fusion , and so cause a blurred and indistinct

of h e M i mage t object . yo p i a from excess of th curvature i s much rarer than e a xial form . We som etimes see a case of apparent myopia

d ue to excess of curvature of the lens , caused

by a spasm of the ciliary muscle . This i s what d i s known a s false myopia , and will isappear f t under the in luence of a ropine , or rest .

Th es e cuts h a v e n ot b e e n m a d e w ith m a th em a t ic a l p re c is i n a r e t ro u h e x e m if t h e o , b ut e m ere l y in t n d e d o g ly pl y

rin c i in v a b ov i us t ra t e s t h e e ff e c t o f a. p pl e o l v e d . T h e e ll d is t a e rv e d t h a t n t p o in t up on a m y op ic e y e . I t w ill b e o b s t h e ra y s f ro m t h e d is ta n t p o in t c a us e t h e im a g e f ro m t h a t p o in t t o s p re a d o ut ov e r a c o n s id e r a bl e a r e a o n t h e re t in a. s A m ill io n p oin t s w oul d m a k e a m ill io n b l urre d s p o t . T h e y w o ul d o v e rl a p e a c h o th e r a n d r e n d e r t h e p ic t ure in d is tin c t .

D onders pronounced every highly myopic eye

a diseased eye , but of late years it has been shown that this remark i s liable to convey a

- D 3 . false m eaning . It is admitted that up to

th e cases are seldom serious , it being generally

possible to give perfect vision by proper glasses ,

- but when th e case is above 5 D . we do not

always ob tain perfect vision by proper lenses .

v c and look for a ri us p a thol og ical conditions .

1 6 4 LE \ V I S PO CKE T

AS D T N AL UC (L . nasus nose ducere to

lead) , That part of the tear duct which extends from the lower part of the lacrimal sac to the ih

f erior - t canal of the nose . It is about n ve eigh hs of a n inch in length and lined with a mucou s

membrane similar to the lacrimal canals . At

the end of the duct we find the valve of H asner .

N P P x ea r oi n t (or un ctum P ro imum) . The nearest point at which the eye can see distinctly when

employing its full amount of accommodation . It varies with the amount of accommodation the

eye possesses . The way to determine the near point is to note the shortest distance at which an emmetrope can read small print with each n eye separately . P roperly speaking , the ear

’ point is that point for which the eyes refrac tion is adjusted when the full amount of aecom

modation is being used .

- S t S M . N ea r igh . ee yopia

’ N e b ula ( L . S light corneal O pacity.

’ - N eedli n g ( need ling) . An operation for soft cata

ract . The lens capsule is needled , and the

aqueous allowed to absorb the lens .

’ - - L . N egativ e ( neg a tive) . ( . negare to deny )

The opposite of positive . The negative surface

of a periscopic lens i s the concave surface .

- - fi L N eon atus ( n e on a tus ) . ( Gr . neos new . na

tus born . ) Newly born

' - - - f- - - h S ee N eotocophtha lmia ( n e ot ok o thal mi a ) .

O phthalmia N eonatorum .

' - - - - S ee S N ep h a b l ep s ia ( nef ah lep si ah ) . now

Blindness . O PHTHALM IC DI C TIO NARY 1 6 5

’ N e h e lo i —e - o — - r p p a (nef l pi ah ) . ( G . nephele cloud

: d ops eye . ) A diminution of vision , cause by a cloudiness of the transparent parts of the

eye .

’ e h r t R t t - - k in N p i i c e i n i i s ( nee frit i ) . A form of

’ fl amma tion of the retina associated with B right s

disease of the kidneys , characterized by white

- streaks along the course of the blood vessels .

N L = - rve n r u n r . e ( . e v s e ve ) A white string like fiber which transmits impressions from an organ

to the brain or from the brain to an organ . N C ra n i a l . , any nerve arising from the brai n

direct . There are twelve cranial nerves , a s follows

1 . O lfactory , special sens e of smell . O 2 . ptic , special sense of sight ( retina ) .

M . 3 . otor O culi , motor nerve for eye muscles

4 . P atheticus , motor n erve for superior oh

lique muscle .

"

5 . Trigeminus , sensory , motion , and taste .

6 . Abducens , motor nerve for external rectus

muscle .

7 . F acial , motor nerve for muscles of face .

8 . Auditory , special sense of hearing .

- P 9 . Glosso haryngeal , sensation and taste .

’

P . 1 0. neumogastric , s ensation and motion

1 1 . . S pinal Accessory , motion 2 1 . H ypoglossal , motor nerve of tongue .

The nervous system is a system of connection an d communication by which the d ifferent or

gans , vessels , and various parts of the body are brought into direct relation with each other a n d timu with the mind , and the various organs s

lated to harmoniou s or alternating action . I t 1 06 LE W I S PO C KE T

consists of the brain and spinal cord , called the

central nervous system , which controls the vol

un tar y actions of the body , sometimes called

the nerves of animal life , and is directly con

n d ecte with the sympathetic nerves , which have

been termed nerves of organic lif e , they be ing involuntary nerves and control the involuntary action of the various vital processes of the

body . The nervous system is divided into the

- cerebro spinal or central , sympathetic , and the

v aso motor . The vaso motor system is a part of the sympathetic system and consis ts of the vaso motor center located in the medulla oh l on gata ; of certain other subsidiary vaso motor

centers in the spinal cord , and of vaso motor t nerves . This system i s connected w i h the

- blood vessels in the various parts of the body . the muscular coats of which are supplied with fi laments and plexuses of vaso motor nerves

“ — which regulate the size of the blood vessels .

They are of two kinds : vaso dilators , stimula tion of which causes‘ dilatation of the blood vessels and an increased amount of blood to a

part , and vaso constrictors , stimulation of which cause s constriction or contraction of the blood vessels and a diminished amount of blood to a

p art . This last named system is very important t o the practitioners of manipulatory forms of

healing , and has only in the past few years

been known to any extent . the vaso motor cen

t er being discovered by S chiff in 1 8 5 5 , and more

accurately localized by L udwig in 1 871 . The cranial nerves are those that have their appar S ent origin in the cranium . ommering and

other E uropean anatomists name twelve pairs ,

1 6 8 L E \ V I S I ’ U C K E T

e a c h one termina te s in a s en s i tive poin t ( rod s " a n d cone s ) and in a ll parts o i the third tunic

( th e t re ina ) , excep t a t th e en tran c e o f th e op tic

v ( t s ) . S e e R t : O t t ner e op ic di c e ina p ic Trac .

H E D O F T H E O P T C N E V A I R E .

l t h n l u p i m os c o p l c v ie w o f t h e O t ic D is p c . T h e s m a ll e c a v a t io n s s e e n a ro x u n d t h e c e n t e r is t h e L a m in a V ' ri o s ‘ b r a . T h e l n il lzl e p is n c i rc l e d b y t h e W h it e S c l c l n l in er ( c l a s o ‘ R s. l t h e d a r k t h o ro l i iu l R in g m a rk e d o L n g it ud in a S -c l o o r t n f H i m! o r O t ic N e e e l p v ; r. t h R e t in a h t ic ‘ ‘ ; . O p E x c a v a t io n u n i l ( u n a l f o r ( e n t rn l r t e ry ( o ro us o t ic us ) c h t e C A p p ; . h h o ro id 3 O p t ic ; ,

c . t h e n a r ro w t in e rs n n c e w h ic h c o rre s p o n d s t o t h e S c l o rn l R l n r s c c p, n by ( h e fl p l i i h n l m o s c o e s S c ie p ; . ro l l c : c l E n t r a ‘ , n c e o r s h o r t t l l in r v A r t e ry .

e ra s t e a - - t - - ( i . G r N u h ni nu ras hen ah ) ( . neuron

v a s th c n e ia s s ner e weakne . ) E xhau s tion o f v ner e force . O P HT H A L M I C til l

’ - - ti G r. t s N eu ri ti s ( neu ri s ) . ( neuron nerve i i

inflamma tion . ) Inflammat ion o f th e O pti c

nerve .

’ ‘ - - r ‘ N eu rology ( nu rol o ( G r. neuron nerve

r - z t f s log ia d is cours e . ) A s udy o nervou

s sy tem .

“I“T H E E Y E F R O M T H E T E M P O R A L S I D E P T AR O F T H E O RBI T R E M O V E D .

E e a w it a r o e l . h t f e x a r c t s u e y b ll p t e r n l u m s c l . o S u e r i r M a x i a 3 T h ird a ir o r i n e r v e s . . o t o r p ll . p ( M O c ul ) T h e a re d is t ri t e d 0 a l l us s h e e e x c e t y b u ( t h e m c l e o f t e y . p t h e S u e r io r O i ue E x t e r n a l c t us n d h e D il a t o r p bl q , R e a t M s e s o I v r s o f e d in u c f l i i 4 . r t a i o N e r e s e ( . u h r f v l F p , g S l l 'v rl fl l ‘ U l i l l uv us c e s ( i S x t a ir N e r ve s f e e d M . . i h o f l q l p . in E x t r a n s 8 N s e r i o i ia r e r ve t e n t h e b e . g e n l v i . . C l y n g g l

' e ro e a P t o i N u d l gi a . ain or excessive s ensib ili y

h e t re tina .

e r e t N u od a ro p hi a . A trophy of th e re tina .

e r ret t s - ro - re t- ih G N u o ini i ( neu ( r. neuron

i. G t r t s . t o nerve . re ina . i i ) Inflamma ion f

th e t op ic nerve and re tina .

’ — z e - z s e ut a e t i e L n ith r. N r li ( neu ral ) . ( . neuter e e ) The me thod of coun terbalancing or doing away

w t e i th power in lenses . In ord er to de erm in

w t s is s s he her a len of plu or m inu power , hold

. 2 up a few inches from th e eye and look a t 1 70 LE WIS PO C KE T

some distant object through it , then move the lens from side to side a n d if the object appears to move in the opposite direction to the move

ment of the lens it is a plus lens . If you wish

to find its dioptric power , take from your trial case a minus lens and put them together and

o th e again l ok through them at obj ect , and should the obj ect still move against the move ment of the lenses the minus is not strong O n enough . the other hand , should the move m ent be reversed and now the objects appear

to move with the lenses the m inus is too strong , and you must find the minus lens that will

allow the object to remain stationary . Whatever minus lens is required to do this will be of the

same power as your plus lens ; for in stance , it will require a — 3 sphere to neutralize a + 3

S phere . When you look at an obj ect through

a minus lens , and move the lens as explained

above , the obj ect will appear to move with the

movement of your lens , and in order to find its dioptric power use plus lenses as in the previous test until all movement of the object

looked at has disappeared , and then the minus

lens will be the same power as your plus . If

the lens is compound , use the weakest spherical lens which neutralizes the motion in one direc

tion ; this usually gives the spherical surface , then use a cylinder to neutralize motion at

right angles to this . If in order to neutralize

a given compound lens , + 2 sphere combined ° with + 1 cylinder, axis 9 0 is required , then the lens being neutralized is a — 2 sphere com a — 1 bine w ith cylinder , axis etc .

- z t t n . L i r Ni c i at i o ( nik tit t . n ctita e to

1 72 LE W I S PO C KE T

tin guis h or the greater the distance at which it

can di stinguish an object of given size , the

greater i s the acuity of vision that it possesses .

S for t uppose , instance , hat the eye is j ust able to distinguish the letters in the line marked 50 on the S nellen ’ s test type from a distance of

twenty feet , then the vision would be The vision in this case would not be as good as if the line marked 40 had been read from the same distance ; and in order to have normal vision the patient should read the line marked

' 2 0 at twenty feet , with each eye separately , then the vision would b e known as S ometimes the patient will read the line

marked 1 5 or even 1 0 from twenty feet . In

this case the vision i s exceptionally acute , and i s desi gnated as or Normal vision does not indicate that the eye

is normal , as the patient may be straining to

bring the vision up to thi s point , as in F aculta

tive H ypermetropia . Again , an emmetropic eye

does not always have normal vision .

’ - - A n . N otation (no ta shun) . (L . otar e to mark ) system of written signs of things and relation s

used in place of common language .

' - - - f N ub ecula ( nu bek u la) . (L . dim o nubes

s . cloud . ) S light cloudines of the cornea

' - - N uc lea r ( nu kle ar ) . P ertaining to the center .

The controlling center of activity .

N uc l ea r C ata ra ct . S ee Cataract . z me r t n . L . N u a io ( . numerare to count ) The art

of reading numbers .

’ - - - N ume ra to r (nu m e ra tor ) . The number , in a O PHTHALM IC DIC TI O NARY

f “ common raction , which shows how many parts

of a unit are taken .

' N t lo m k - - - - : c a a o Gr . n n y p i ( y tal pi ah ) . ( ycto igh t

a laos e s obscur op eye . ) Night blind

ness . A condition where a person does not possess normal night vision

’ N ctot h lo is n k - -t f- - = t y yp s ( y to y lo sis . ) ( Gr . nyx nigh t = l in n S f yp h los is b d e s s . ) tate o blindnes s

at night time .

' t m - - n t m = Nys a g us ( nys tag mus ) . ( Gr . ys a g os a

nodding . ) S hort , j erking movements of the eye which are very rapidly repeated and always i th occur n e same d irection . The movements

of . f . the eye , as a whole , are not a fected by it D f t e ective vision of. such cases is not to be a

tributed to the nystagmus , but , on th e con

f V rt l n rary , i s the cause of it . e i ca . , the eyes

continually move vertically . Lat e ra l n . , the eyes

z Rot r n . constantly move hori ontally . a y , the

eyes constantly ro tate .

’ BF T O - -k - L 0 US CA I N ( ob fus a shun ) . ( . ob to

s ward fus cus dark . ) An obscuration of vi ion

or a confusion of sight .

. t O bj ect S omething visible or tangible . Tha

which is seen . An external something the

n image of which is upon the retina , which is i tellig en tly impressed a n d appreciated by th e

brain .

’ - - L b z a a in st acere O bjectiv e ( oh jek tive ) . ( . o g +j

r s te cast . ) S ymptom o bserved by operator

usually with ophthalmoscope or retinoscope . S ymptoms which the refractionist discovers by 1 74 L E W I S P O CK E T

means of one or more of his five sen s es .

e t iv E t j c e xa m i n a io n . An examination condu ’ t independent of the patient s statemen s ; e . g

retinoscopy , ophthalmoscopy and many oth e

tests by means of instruments . S O bliq uze . lanting ; placed in a plane b etween th e hori ontal and vertical planes .

’ O c c t k - - - i p i a l ( o sip it ai) . P ertaining to th e back t part of head . O c c i p i a l lo b e is the posterior

portion of the cerebral hemisphere .

O t - F r n t c c i p i o o a li s . The muscle which lifts the

eyebrow s upward . S upplied by the seventh

nerve .

' P k - - B O c c l us ion of t h e up il ( o klew shun ) . locking up of the pupil by a membrane

’ “ - - e L . A e O c ll us ( o sel lus ) . ( . the eye single y e .

’ - - O cul a r ( ok u lar ) . (L . oculus eye . ) That which

pertains to the eye .

O cul a r Ref ra ctio n . The science treating of the

op tical conditions of the eye , the estimation of its errors of refra ctiOn and t heir connection

with lenses for the eye .

t i O c ul a r S p ec res . maginary objects floating b e

fore th e eyes .

’ - - = O culi s t ( ok u list ) . ( L . ocul us eye . ) A physi

oian and surgeon who has received the degree, “ ” Doctor of M edicine , and makes a specialty of

th e eye and its diseases .

' O c ulo- Moto r C e n t er is a point situated beneath the floor of the aqueduct of S ilvius around which the impulse t o us e accommodation uni ted with the action to use the different muscles of

the eye is stimulated .

1 76 LE W IS PO C KE T

“ ’ th m of- - - e - Gr h th t O a a a . o a p h l l gi ( thal mal g ah ) ( . p

2 — mos eye i a lgo s pain . ) S udden violent

th e t of pain i n the eye , not resul inflammation ,

but n euralgic in character .

’ th m t r of- - - - - r O p h a l a o p hi a ( thal mah tro fe ah ) . (G .

m 2 t t op h th a l os eye a rophia a rophy . ) Atro

phy of the eye .

’ - - - O p hth a l mi a ( of th a 1 mi ah ) . S evere inflammation

of the eye . Thi s more particularly applies to

th t th e d e conjunc iva of eyeli s and eyebal l .

’ ’ h h l m m n t m Gr . o t a os O p hth a l i a N eo a o ru . ( p

! : - n n t s n w . eye + L . eo a u e born ) A form of purulent conjunctivi ti s whi ch attacks newly

born children .

’ - - O ph th al mi c ( of thal mic ) . That which pertain s m L to to th e eye . O p hth a l i c e n s , a l ens be

worn before the eye .

’ - - - O p ht h a l mit i c ( of thal mit ic ) . That which appl ies to inflammatory diseases of th e deeper as well

as the superficial structure s of th e eye .

’ - - - o h th al mos O phtha l mit i s ( of thal mi tis ) . (Gr . p t f eye i tis . ) Inflamma ion o the eye , more o es p ecia ll y th e globe with its membranes .

’ h - - r- - r . O p ht h a lmob le n n o rr o ea blen u re e ah ) . ( G O p h th a l mos eye blenna mucu s rh oia

A f . flow . ) flow of mucus rom the eye

’ - - - - O p htha l mo ca rc i n om a kahr si no mah ) . Cancer

o f the eye .

Gr o h th a l mos O p hth a lmo c el e . ( . p eye kele

l oma . hernia . ) S ee Sta p y

’ - - - h th lmos r . o a O p hth a l mo c o p i a koh pee ah ) . ( G p

2 = F t eye k op os f atigue . ) a igue of the eyes ;

Asthenopia . O PHTHA LM IC DIC TIO NA R Y 1 77

’ ht h m - - - " O a d a e . h p l o yni din ah ) ( Gr. op th a l mos

—— d n z in eye l o y e p a . ) N euralgic pain of th e

‘ ’ O t m r - - - a r . p h h l o g a p hy mog rha fee ) . ( G O p h th a l

s A mos eye graphe a de cription . ) de

scrip tion of the eye .

’ O ht a m s t of- - moI - o- O n p h l ologi ( thal gist ) . e who prac tices ophthalmology and has taken th e de D f ” o M . O gree , octor edicine An cul ist .

’ - - - - O p ht h a l molo gy ( of thal mol o gy ) . A study of the it eye and s diseases .

’ t h l m m r i - - - E O p h a o a c os s ma kro sis ) . nlargement

o f the eyeballs .

' ’ t - - - h th lm s O m h Gr . o a o p h h a l om a l a c i a ma la s a ) . ( p t eye malak ia softness . ) That condi ion in which there is abnormal softness of th e eye

ball .

’ O - - - h h l mos h m G r . o t a p th a l o p a thy mop a thee ) . ( p

r : t s o f eye pa ho suffering . ) Any disease

th e eye .

’ O i - - - h th a l ht ha lmO ht h i m t th i Gr . o p p s s o sis ) . ( p t mos eye phthi s is wasting . ) Tha condi

tion in wh ich there is wasting of the eyeballs .

’ O t a m e - - - h th lmos a e . o a p h h l o p l gi ple j ah ) . ( Gr p i eye p ege s troke . ) P aralysis of the ocular

s o f th P rt muscle e eye . 0 . a a a form n wh ch i l , iz i only som e o f th e muscles are paraly ed . 0 .

P s ro gr es s i v e , a gradual paralysis of all th e mu

f s n d cl es o bo th eyes . 0 . T ota l, when the iri a

d t s c iliary bo zy , a s well as the ex ernal mu cle s , are paraly ed . O . E xt e rn a , when th e external

z. t f muscles are paraly ed 0 . l n e rn a , paralysis o th e internal muscles . 1 78 LE W I S P O C KE T

’ O ht ha lmo t om - - - p p a mop to mah ) . P rotrusion of

the eyeballs .

' O ht ha lm t i - - - o os a . r l m p p mop to sia) ( G . op h th a os

eye ptosis a falling . ) P rotrusion of the

eyeball .

’ O t a mor h a - - - - ph h l r gi a mor rha gee ah ) . (Gr . op h — th al mos 2 rh e n mi eye l g y I burst forth . )

H emorrhage from the eya or orbit .

’ O t m rh x - - - a or e s . ph h l i mor rex i s ) ( Gr . O p h th almos

eye rhexis rupture . ) The bursting of

the eyeball .

’ O t a mos o f - - - h p h h l c p e ( o tha1 mo s cope) . ( Gr . op th l m k a os eye s op eo I examine . ) An ih

strument for observing the interior of the eye ,

and thus - determining the appearance of th e

m edia , the condition of the retina , choroid and

optic n erve , and the state of the refraction . The O phthalmoscope consi sts of a round

e . mirror , with a small perforation in the cent r

The surface of the mirror i s usually concave . The more improved ophthalmoscopes have a

reversible mirror, one side of which is flat and

the other concave . In addition to this there are located on the back of the ophthalmoscope several wheel s which contain a great variety of

convex and concave lenses . B y rotating these wheel s the different lenses conta ined in them can be thrown immediately behind the aper

ture in the mirror . There are two methods of examining the eyes

W ith th e ophthalmoscop e , viz . : the indirect and

the direct . Th e indirect m ethod is n ot of much value s o far as es timating the refraction of the eye i s

LE W I S PO CKE T

w ell to place the patient und er th e influenc e.

e o f atropine , assuming that th operator h a s thorough control of his own accommodation

and can suspend it at will . B y reflecting the light into the E mmetropic eye we illuminate the retina ; the retina again reflects the light so that it passes through the

pupil and out of the eye . The rays from each

’ reflecting point emerge from th e eye as parallel

' t s rays . Therefore , if the opera or s eye i E mme

tropic he will , by the aid of these rays , be able to d istinctly see the details of the fundus in th e

’ back part of his patient s eye , because th e

' l ’ ight leaves the patient s eye as parallel rays ,

’ and the operator s eye , being also emmetropic .

i s adapted for parallel rays , and hence he has each point on the patient ’ s retina represented t by an exact focus on his own re ina . It can readily b e s een that if a patient has used any accommodation the rays would le ave

h is a s . arall el eye , not p , but as convergent rays . and therefore th e operator would have been unable to distinctly s ee the details of th e fun

n dus . O the other hand , if the patient had been under the influence of atropine and the rays

” h a d left the eye as parallel rays striking th e

’ observer s emmetropic eye , as parallel rays , they would not focus upon the operator ’ s retina

th e if he had used any accommodation . H ence necessity of thorough relaxation of a ccommo dation in both the patient and operator . We will next suppose that the hypermetrop ic eye is being examined by an operator who is emmetropic . The rays of light . will leave the h ypermetropic eye as divergent rays and there

LE W I S P O CKE T

h t of t is eye , a concave glass must be used s rong enough to render parallel the convergent ray s

which are leaving the myopic eye . It i s usually conceded tha t in astigmati sm

the ophthalmos cope is of little or no value . I t i s true that w e may be able to s ee the blood vessel s and the edges of the optic disc clearer

. t t i n one m eridian than in ano her . and hat we m a y use a gla s s strong enough to render plain the

m eridian which was at first blurred . and there by dim the meridian which was firs t seen

plainly . The glass which clears up th e merid ia n which seem ed blurred at first would be the measure of the ametropia in th e meridian at r ight angles to it . It must also be remembered that if the operator i s not emmetrop ic he must either have his own refraction properly corrected by glasses , or he must make deductions or additions . as th e case may be , to or from whatever glass clears up the

’ F r r . o etina in the patient s eye instance , if th e operator knows himself to be hypermetropic

to the extent of one d ioptry, and on examining

’ t - his paient s eye he finds that a plus 3 D . glass is required to enable him to see the details of

’ h is patient s fundus . he then knows that his " patient has two dioptries of h yp ermetrop ia , b e O PHTHA LM I C -DI C TI O NA RY 1 8 5

cause one of th e three was required to correct

his own eye . and likewise if he h ad been exam

i t n - ning a myopic eye and found hat a mi us 2 D .

’ wa s to t lens required see h is pa ient s reti n a , he

would know that his patient h ad three dioptri es

i of myopia , because he himself was one diO p try

hyperm etropic .

’ ’ O t a m s h - - - p h h l o c o py ( op thal mos copy ) . The art of judging healthy or diseased conditions of the

eyes by m eans of the ophthalmoscope . There are two methods of exam ining the eyes with iz th e ophthalmoscope , v . : the direct and the

indirect .

’ ’ O t a m s ta t of- t — - Gr h h l p h h l o ( hal mo stat ) . ( . op t a

mos eye statos made to stand . ) An eye

speculum .

’ O hth a lmula of- l - mu- p ( tha lah ) . A cicatrix located

upon the eye or its appendages .

o s is . O pt i c . (Gr . p vision ) That which pertains

to the science of light , and also to the eye

itself , together with its functions .

O pti c At ro p hy . A partial or total loss of sight

due to atrophy of the optic nerve .

O pti c A x i s . A line drawn through the center of

the cornea , through the nodal point to the t inner side of the macula lutea . In o her words . through the center of the eyeball from before

back .

r O pt i c G ro ov e . A transverse groove on the uppe surface of the sphenoid bone on which the optic

nerve rests .

N . O pti c ue rit is . Inflammation of the optic nerve

O t P . p i c a l . ertaining to the organ of vision 1 8 6 LE W I S PO CKE T

C riti ca l C e n t e r. A point where the secondary axis crosses the principal axis on line wi th the thickest part of a plus sphere or the thinnest

part of a. minus . A ray of l igh t w h en passing through the optical center of a lens will always emerge parallel to the incident ray or in the

n . same pla e O p t i ca l C ent er of a Lens . The t center of refrac ion . It is found by making two

parallel radi i of curvature , and connecting the

points in which they meet the surfaces . The

point at which this line cuts the principal axis ,

i s the optical center .

t t L th O p ical C orrec ions . enses that change e d i rect ion of light rays entering the eyes to such an extent that the eyes are adapted to receive fi and focus them upon the retina , creating a rti cial emmetropic conditions when ametropic con

dition s exist .

’ O t mm s r - -ur p i c Co i s u e ( kom mis ) . The linking or joining together of the right and left opti c

nerve .

O p ti c Di s c . That spot on the retina which marks

the entrance o f the optic nerves into the eye .

It is also called the blind spot , or papilla .

x O pti c E cavati on . The depression in the optic

disc.

O t rv e p i c N e e . S e under nerve .

’ O - il - ptic P a p illa ( pap lah ) . The elevation of the optic -nerv e head ; also called the optic disc and

blind spot .

’ - - th e O pti cia n ( op tish ah ) . A person skilled in

manufacture of optical instruments .

E 1 8 8 . L W I S PO C KE T

each optic tract d ivide , and the outer fibers of each tract are continued into th e nerve of th e

same side , while the central fibers of each tract continue into the op tic nerve of th e opposi te t side , crossing each o her and passing through

th e f optic oramen to enter th e eye . The dura mater and pia mater which lines th e skull passes through the optic foramen ( hole into orbi t ) and forms the optic sheath or cover ing of the optic nerve until it enters th e

lamina cribrosa ( sieve - like opening of th e eye ) t t and spreads ou to form th e re ina .

’ - O i . pt is t ( op t s t ) . A person skilled in optometry

’ - - t s - Gr . o o O ptog ra m ( op to gram ) . ( p visible l

r m z t t g a ma a picture . ) A fain image s amped

on the retina for a brief period .

’ - - - O e e O . ptology ( op tol o g e ) . S ptometry

’ n r fra c . O pt om et ri s t . O e who measures the eye s e

tion .

’ - - - tik = b . r o os e O pto met ry ( op tom e try ) (G . p

— longing to sight l me tron measure . ) The science and art of employing th e various meth

ods of measuring the optical state of th e eye .

’ ’ O ra S e rra ta ( a serrated border ) . The anterior it limi t or edge of th e retina . S o named from s

- saw like appearance .

O rb . A spherical body .

' = O r L a . bi cul a r. ( . orbiculus small disc ) Annu

lar , circular .

O rbi cul a ris P a l p eb ra rum . The circular muscl e of t h e eyelids .

r z - O bi cul us C i l ia ris . A one of about one sixth of O PHTHALM IC DIC TIO NARY 1 8 9

: an in h in width . It is direc tly continuous wi th

th e anterior part of the choroid .

’ - L z - t r . . O rbi ( o bit ) ( . orbita track ) The bon y

socket in which the eyeball is placed . The orbi ts are conical in shape w ith their apices extending backward and toward each other

while the front or base of the cone is open , leaving the eyeballs to b e protected by the ey e

lids in front .

An a to my of O rb it s . The orbits are two pyra midal cavities inches wide by 1 34 inches

deep , situated at the upper and anterior part

a e t th e . f c of . their bases being direc ly forward and outward and their apices backward and

inward , so that the axes of the two if continued backward would meet over the body of the

ri s sphenoid bone . The orb it is lined with p e o

. E of teum , the periorbita ach orbit is formed

th e f . seven bones , rontal , the sphenoi d , ethmoid

superior maxillary , malar , lachrymal and pal f th ate ; but three of these , the rontal , e moid and

sphenoid , enter into the formation of both or

bits , so that the two cavities are formed of

eleven bones only . The orbital opening , or

mouth , i s called aditus orbitae (Aditus O rbitae

— entrance to orbit ) . At the apex , or back part

of the orbit on the nasal side , is a small circu

lar opening known as the optic foramen , which transmits the optic nerve and ophthalmic

artery . There are nine openings communi v iz h ea tin g with each orbit , . , t e optic foramen ,

- the spheno maxillary fissure , sphenoidal fissure

supraorbital foramen , anterior and posterior

' i ethmoidal foramina , infraorbital canal , mala

foramina , and the canal for the nasal duct . 1 330 LE W I S PO CKE T

S pheno - maxillary fi ssure transmits the superior

r maxillary ne ve and its orb ital branches , the i nfraorbital vessel s , and the ascending branches

’ - M from the spheno palatine or eckel s ganglion .

S phenoidal fi ssure transm its the third , the r fou th , the three branches of the ophthalmi c d ivision of the fifth , the sixth nerve , some fila ments from the cavernous plexus of the sympa

thetic , the orbital branch of the middle m enin

g eal artery , and a branch from the lachrymal t ar ery of the dura mater , and the ophthalmic

vein . S upraorbital foramen transmits the

supraorbital artery , nerve and vein . Anterior ethmoidal foramen transmits the anterior eth

moidal vessels and nasal nerve . P osterior eth moid al foramen transmits the posterior eth

moida l vessels . l nfraorbital canal opens just

‘ h rb it M below the margin of t e o . alar foramina i s a passage for nerves and vessel s from the

orbit .

’ - - 1 P th e O rbita l ( or bit a ) . ertaining to orbit .

’ - - = i n L ori o b e in n in . O ri gin ( or j i ) . ( . g g g ) The

more fixed end of a muscle ; for instance , the

end attached to the bone of the orbit .

’ - - h r - -i O rtho ch romati c ( or tho c o mat c) . (Gr . orthos

straight chroma color . ) A term used by photographers denoting that the colors are

normal or correct .

’ - - - O rthometer ( or thom e ter ) . (Gr . orthos straight fi n d metron measure . ) An instrument for ing the exact relative protrusion of the two eye~

balls .

’ - - O rthopti c ( or thop tic) . (Gr . orthos straight = l the op tikos rel atin g to sight . ) R e ating to

1 9 2 LE W I S P O C KE T

’ O a ox - - o - - r ox xyo p i ( y p i ah ) . ( G . ys acute ops

eye . ) That con dition in which the sight is

abnormally acute .

’ P Y B L E P RO - - b l ef— -on Gr AC H H A N ( pach y ar ) . ( . a h t — p c y s hick l blepharon eyelid . ) T h a t condition in which the eyelids have becom e

thickened .

’ P a eb ra - L = l p (pal p e ( . p al p eta re to palp i t Th ate . ) e eyelid . I n f e rio r lower eyelid . w

S r P . T rt i P up e io r , upper eyelid . e a third eye

. ee M N i ti i n lid S embrana c t a s .

’ - - z P . r . l r i a l p e b ra l ( pal p e bral ) . ( G p a p eb a eyel d )

That which relates to the eyelid .

f - t P a lp eb ra l Fi s s ure ( p al p e b ral ) . The space b e

tween the free margins of the eyelids . The outer angle of fissure i s called the external can

th . thus ; the inner angle , e internal canthus

The small ‘ space between the lids and globe a t

l r m inner angle is called the a cus l a ch y al is .

' - - - t e . L P a lp eb ri is (pal p bri tis ) ( . palpebra eyelid

Gr. itis inflammation . ) An inflammation of

th e eyelids .

’ - P L . a nn us (pan nus ) . ( . a piece of cloth A

web - like patch of grayish membra n is h tissue

r n h usually cove i g t e upper half of the cornea ,

. v making it almost opaque . It is us uall caused by the rubbing of roughened or granulated lids over th e cornea and results in the effort of

n nature to protect this m embra e .

’ - - - - n fl P a n o phtha lmi a ( pan oi thal mi ah ) . An i amma

tion of the entire eye structure . O M C C O 1 9 3 PHTHAL I , DI TI NARY

’ t - ff- - - t m r. P a n op h h a l i i s ( pan o thal mi tis ) . ( G pas

(pan ) all op hth almos eye . ) General ia

fla mma tion of the eyeball .

i i . P a n t s cop c A lens tilted outward at the top .

’ - - - r P a n tomet e r ( p an tom e te ) . An instrument for measuring angles and determ ining p erp en dicu

lars .

’ - - P a il . L p ill a ( pap lah ) ( . nipple . A conic ele

- P vation observable at the optic nerve head . . h Lac ryma lis , the mound at th e inner canthus

of the eye pierced by the lachrymal puncta .

’ P t - - - a p illi i s ( pap ii li tis ) . That condition in which there is an inflammation of the optic disc or

papilla .

’ P i r t t - i - - -in - - I n fl a p llo e ini i s ( pap l lo ret i tis ) . amma

tion of the O ptic disc and retina .

’ P a ra b e s - ab - - ara = b es ide l p i s ( par lep sis ) . ( Gr . p F ‘ bl ep s is sight . ) alse vision . P ’ a ra c e n t e s i s . ( Gr . para besid e k en tes is

puncture . ) S urgical puncture of a cavity .

I ’ - - - P a ra c e n te3 1s Co rn ea sen tee s is ) . P uncture of th e cornea .

’ P - - a ra lla x ( par a l lax ) . An apparent displacement

’ of an object , due to change in the observer s

position , or when closing one eye .

’ - - P a ra ll el ( par a l lel ) . That which pursues the

same di rection , but in a separate path .

’ - - - - - P a ra e e e a e ed . ll l p i p d ( par lel pip ) ( Gr . paral n lelos parallel ep ip edo plane . ) A prism

whose bases are parallelograms .

’ - - - - G r m a o . r s P a rall elog a ( par lel gram ) ( . p arallelo

parallel gramma line . ) A quadril ateral

whose opposite sides are parallel . 1 9 4 LE W I S PO C KE T

’ P a ra e s - l - - ll li m ( par a lel ism ) . S ta te of being p ar

allel . That condition in which th e v isual axes

of both eyes lie in nearly parallel paths .

’ P is . r a ra s G . n l y ( I loose I relax . That con dition in which there i s a loss of power of v ol un ta ry motion or of sen sation in a part from

- lesion of nerve substance . O cu lo mot or P . ,

where the motor oculi nerve is affected .

P a ra lys i s of A cc ommodat ion . That condition i n which the function of the branch of th e third nerve which supplies the ciliary muscle s has been interrupted and the eye cannot a ccommo

a t s t date , the ciliary muscles being in s ate of re .

P ’ P a a ra l t ic. Gr c . y ( . affe tion ) ert ining to , or fi a ected with , paralysis ; a person who is f a fected w ith paralysis .

’ - - P r . h a res i s ( par e s is ) . ( G . a relaxing ) A sl ig t

form of paralysis .

’ - - i P r Gr. o s s a o p s is (par op sis ) . ( para beside + p th vision . ) That condition in which e vi sion

to t i s disordered , and may be due ei her a false impression being made upon the retina or a dis

ordered condition of the mind . = P iv . a s s iv e . ( L . p a s s us to endure ) That which t t i s not active ; for insta nce , a muscle ha is in a

s tate of rest .

- - h P ath et i c ( p a thet i ) . That which pertains to

. s u the feelings . The pathetic muscle is the

perior oblique muscle of the eye , which receives

its na me from the fact that the patheticus , or its fourth pair of cranial nerves , control move

ments .

s . P ath ol ogi c . P ertaining to diseased condition

1 9 6 LE W IS PO CKE T

P e r t c S ee P io p i . eriocular .

’ P e r o tomet r -e-o - -et-re Gr i p y ( per p tom ) ( . peri around op tik os referr ing to vision metron

measure . ) M easurement of the visu al acui ty

of the retinal periphery .

’ P - - - - z — e r rb ta i or a . eri a roun io i (per b it ) (Gr . p d l = L . orbita or it b . ) That which relates to th e

lining membrane of the orbit .

P e r b ta l -i- ofl - - ior i ( per bit al ) . Around or about the

orbit .

’ P e r io rb it i - - - i- s ( per e or b tis ) . Inflammation of th e

lining m embrane of the bones of the orbi t. O rbital periostitis . 0

’ P e r s te t s - e- - - i - io i i ( per os te tis ) . Inflammation of

the periosteum .

’ - - — P e r s t e e - r ert : io um ( per os te um ) . ( G . p around z os teon b on e . s + ) The tough , fibrou mem

brane investing a bone .

’ P e r r - - - - v i p h e a p ho s e ( per if er a f oz) . The subj ecti e t f sensation of a dark spot in a pa ch o light . the

v t cause residing in the eye , optic ner e or ou

side of optic center in th e brain .

’ - - - P r : 2 r . e i p ha c iti s ( per i fa s i tis ) . (G peri around — 2 th e l p h ak os lens itis . ) Inflammation of

crystalline lens of the eye .

’ P e i h - ii- - t s r p a cus ( per a cus ) . The crys alline len

capsule .

’ - - - ri z roun d — P r r . e a e i ph e ry ( per if er y ) . ( G p l = p h ero I carry . ) Any outward part or sur th face ; for instance , the border of e cornea or

crystalline lens .

’ — P e r s c - - -i r eri z a roun d i o p i c ( per is cop c ) . ( G . p l k = v s op eo I view . ) A lens ha ing a concave O PHTHALM IC DI C TIO NARY 1 9 7

P and convex surface . eriscopic lenses are al so called m eniscus lenses ; taken from a Greek L word meaning a crescent . S ee ens .

' P r t - it - - e om o . i y ( per me ) ( Gr . peri around

t m = in cis i n o e o . ) An operation for the treat

ment of pannus , by removing a strip of the con

un iv j ct a around the cornea .

’ r - - -k - P e iva s c ul a r ( per i vas u lar) . ( Gr . peri around

L u . . vasculum vessel . ) S rrounding a vessel

’ P e r v t i as c uli i s . ( Gr . peri around L . vasculum

vessel iti s . ) Inflammation of the sheath

of a vessel . This is an increase or a hyperplasia

O f the connective tissue about the vessels , prin

ci al l p y, and usually , the arteries .

’ P e rs ic ilium - -il -i- p (per spic um ) . An apparatus to

enable an individual to s ee minute bodies , or

which will improve the eyesight .

’ P es corv i n us . That which is commonly known as

’ crow s foot ; or wrinkles at the outer corner of the eye :

P t e it . F rancois P ourfour du P etit , F rench sur

- geon and anatomist , 1 664 1 74 1 . P ’ etit s C a n a l . The space b etween the suspensory ligaments in which the edge of the crystalline

lens with its capsule is inserted .

' P - h a eo (fak O ) . P refix meaning of, or pertaining

to , a lens , especially the crystalline lens .

’ P - - k = t s . ha ci i ( fas i tis ) . ( Gr p h a os l en s itis . )

Inflammation of the crystalline lens .

fi P - - - h - ha c oma la c i a ( fak O mal a s e a h) . ( Gr . p h ak os

t . lens malakia softness . ) A soft catarac

’ P a om t - - - k = l en s h c e er ( fa com e ter ) . ( Gr . p h a os

me r n = m r t o eas u e . ) An instrument for meas 1 08 LE W I S PO C KE T

min uring the curvature of lenses , and so d eter

ing their refractive power ; if they are cyl in

d rica l , will locate their axes .

’ P a s r t -k - l - - k c c e s a s c e r . h h o l o is ( o O sis ) ( Gr . p a os

s k l r i lens e os s hardening . ) H ardening of

the crystalline lens .

’ P -k - k = a c s c fa O r. h a n h o o p e ( scope ) . ( G p os l e s

s k o = p eo I view . ) An instrument used for viewing the accommodative changes of the

crystalline lens .

’ k - k - k = P t i r . h a s en ha i i s ( fa tis ) . ( G p o l s itis . )

Inflammation of the lens . A supposition exis ts t hat the crystalline lens may become inflamed .

’ - - m = r . h a n ta s a a n P ha nta s m a ( fan tas mah ) . ( G p

appearance . ) A disease of the eye in which

imaginary objects are seen .

’ P - o- fo - b i- Gr n e n os h e ngo phob i a ( fen g ah ) . ( . p g

daylight phobos fear . ) S ee P h otop h o bl a .

' " P fi - - s t r t Gr hzimo s i s ( mo sis ) Con i c ion . ( . to muz l e . Abnormal smallness (as of the palpebral

fi s s ure ) .

’ G — P ho rotone . ( r. phora motion l tonos ten

sion . ) An instrument for exercising the mus

cles of the eye .

' - - k r G . P ho s geni c (fos jen i ) . ( phos light

L . g en n a o to produce . ) ight producing

’ - - - A G r. . P hly ctenula ( fl ik ten u lah ) . ( bli ster )

s mal l vesicle or blister .

’ - i fl . P h lys s ( y si s ) . A corneal ulcer “ ” P ho ri a . (Gr . a tending )

P horom et e r. An instrument for determining the

‘ in s uflicien cies of the external ocular muscles .

2 00 LE W IS PO CKE T

’ — P ot o h ob - -f - i- r h z a fo b . G os h h p i ( to O ah ) ( . p lig t h b = o os . p fear ) Intolerance of light .

’ P oto s t - - - : l i h t h p i a ( o top si ah ) . ( Gr . p h os g +

o s is = vi i n p s o . ) That condition in which one

sees flashes of light . It is caused p ither by pressure on the eyeballs or by disease O f the

brain , optic nerve , or retina .

’ P to to - - - - o met e r fO e . h p ( top tom ter ) (Gr . phos

light op tos visible metron measure . ) A device for measuring sensitiveness to light by s howing the smallest amount of light that will

allow an object to become Visible .

’ " P hth s B - s u . i i l bi (tis sis ) . (Gr . a wasting ) Shrink

age of the eyeball .

’

P h s o ca l. S ee y i log i phys iology .

’ P fiz- - l - - e r — s O G . hy iology ( e O j ) . ( physis nature l

lo i = dis ur g a co s e . ) That department of nat ural science which treats of the organs of th e

body and their functions .

’ t - - - P hys o s i gmi n e ( fi s o stig min ) . The same as

eserin .

P i M t L a a er ( . tender , affectionate mother The innermost membrane of the brain and spinal

'

cord , optic sheath , and capsule O f Tenon . = P me L in ere to . ig nt ( . p g paint ) The coloring

matter in the choroid coat ; the iris , etc .

’ ’ - - - - - L P il os eba c eous ( pi lo se b a ce O us ) . ( . pilus R hair sebum suet . ) elating to the hair

follicles and sebaceous glands .

’ n - wek - u- L in uis P i gu ec ul a (pin g g y lah ) . ( . p g

fat . ) A small , yellowish elevation , situated in

the conjunctiva near the margin of th e cérn ea .

F ound in old age . T O P H TH A L M TP . D I M o N A u I 2 01

P i n hol e Dis c . An opaque d isc with a pinhole in

th e center , found in the trial test case . It is placed in the trial frame quite close to the eye

under examination . This perforation gives pas sage to a small pencil of light which passe s through the center of the retra ctin g media of

the eye . If the patient can see better through

the pinhole , the retractin g system i s at fault ,

and vision can be improved by glasses . If, on

the contrary , vision is not improved , then we suspect a defect in the sensibility of the retina

or the transparency of the media of the eye .

P k E e . in y A catarrhal conjunctivitis . The eye

ball is of a pink or reddish color . It is a con ta gious disease which occurs among cattl e a n d Q

horses as well as in man .

’ P r r l r l a da o s i s ( G . p a da os flaccid oma tu

mor ) . That condition where there is a soft

tumor on the eyelid .

P L la n = fl a n e . us a t . l ( p ) When applied to glass ,

- a flat surface i s meant . A plano concave lens is ' a lens having one side concave while the

other side is flat . A plane disc , or a plano , i s an accessory found in the trial case which has

two surfaces , both of which are plane .

’ - ik = m P Gr l a s t os for . l a s t i c ( plas tik ) . ( . p ) Tend

ing to build up tissues .

’ P x - L l t r l e u s ( plex us ) . ( . p ec e e to weave . A

network or interjoining of nerves or vessels .

r P l i ca ( L . p lica e to fold ) . A fold . Applied to a disease in which the hairs become tangled and

glued together .

’ - c n u P li ca S e mil un a ri s ( ply kah ) . A fold of o j n c

t O f e iva near inner canthus the ye, 2 02 LE W I S PO CKE T

P o n t L . un t m i ( . p unctum ) The far point or p c u remot um is the farthest point at which the eye can see cl early and distinctly with the aecom

m da i n o t o at rest . The near point or p un ct um p rox imum is the nearest point at which the eye can see clearly With all of its accommodation in

use . P . of Rev e rs a l . In R etinoscopy the t erm is used to designate the point between an erect

and an inverted image , where the change from

one to the other occurs . Where convergent rays

change to divergent rays . The myopic far point i n retinoscopy is wherze the movement of the reflex appears neutrali ed . In other words , it is that point on one side of which the shadow

r movement is diff erent than on the other . F o

- instance , a t any position nearer the eye than the point of reversal the shadow will move

against the mirror , and at any position farther from th e eye the shadow will move with the

mirror . This refers to the concave retinoscope . With the flat mirror the movement would be

. x t n t directly opposite . P of F i a i o . The poin for

which accommodation of the eye is adjusted .

P ola rimeter ( L . pol aris polar Gr . metron

measure ) . An instrum ent for measuring the

rotation of polarized light .

l k eo P ola ris cop e ( L . polari s po ar s op I ex th e amine ) . An instrument used in showing

phenomena of the p olarization of light .

P ola rizati on . The production of a condition in light by virtue of which a ll its vibrations take

place in one plane , or in circles and ellipses . h P ole (L . polu s pol e) . T e s ummit of a spher

ical surface .

2 04 LE W I S PO CKE T

if ametropic ) cannot produce sufficient a ccom modation for the reading distance, the condi

tion is called presbyopia . The average age when e this stat of affairs is present is 4 5 , and as age advances the accommodation gradually dimi n ishes and the presbyopia correspondingly ih

creases . The amount of presbyopia is rep re sented by the di fference between the number of dioptries of comfortable accommodation present

and three dioptries , which must be made good

by plus spheres . The presbyope sees well at a

distance , providing there is no error of refra c

tion , but has difficulty in maintaining good

vision for near work , and the eyes become tired

after reading , especially at night . H e h a s trouble in seeing small“ obj ects because he has

to hold them far away , and consequently gets a

smaller visual angle . B efore correcting pres

‘ byop ia it is necessary to test the patient s d is n tant vision a d correct any error of refraction . Then place th e reading chart in his hand ; if he cannot read with comfort at the distance he

wishes to hold it , add plus spheres O f even amount in front of his correction until you find h t e weakest that will allow comfort in reading . The distance for which the presbyope requires glasses will also vary much according to his or

her occupation ; ordinarily it is thirteen inches . This gradual failure of accommodation is due

to hardening of the crystalline lens , loss of

power of the ciliary muscle , or both .

’ P r t - - L r = b efore s r n . a e e c i p io (pre scrip shun ) ( . p = th e + s crib ere to write . ) The formula for

d e s i lenses required by a patient , which are g O PHTHALM I C DI C TIO NARY 2 05

n a ted by technical characters placed on blank s

arranged for this purpose .

of P ri n c i p a l Foc us . The focus parallel rays of light on the principal axi s after being reflected

or refracted .

T P ri n c ip a l Me ridi a n s . h e meridian s of greatest

and least curvature .

' P r i n c ipa l P la n es . S traight lines which pas s

through the principal points , p erpendicular to

the principal axis .

P m - r s . d i When applied to optics , is a we ge shaped , transparent body of glass h avin g two plane

sides , employ ed for the purpose of bending ray s

of light . A prism is not a lens , and a ray of

light is always bent towards its base . It is u sed

in s uflici n ci s in making tests for muscular e e , and sometimes prescribed for constant wear in case s

of heterophoria . P risms are numbered by the angle which their surfaces incline toward each other ; for

° instance , four 90 prisms with their bases and h apices placed together would form a circle . T e bending power the prism possesses depends upon the di fference of density of the glas s itself

and the medium which it is in . The ordinary prism is made O f crown glass and deviates a

ray of light about hal f of its own value ; that is , a 4 ° prism would deviate a ray of light Dennett in hi s m ethod of measuring prism s

calls his unit the centrad , which is the hun

r d edth part of a radian , a radian being the angle subtended at the center of a circle by an '

arc , which i s equal in length t o the radian .

P rentice Method is the prism dioptry , which LE W I S PO C KE T

is any prism that has the power to deflect a ray

'

of light 1 cm . for each meter of distance . These three methods of numbering prisms differ Very little for low degrees in op h th a l

mology. t Ro ating P ri s ms . If two prisms of equal s trength be placed with the base of one over

th e a h z pex of the ot er , they neutrali e each

other , and if we rotate them in opposite direc tions we O btai n the effect of any pri smatic de

“ g ree up to their combined values . A pri sm m for s no imag e and has no focus , and when t looked hrough , the eye turns toward the apex .

Dea ton P . , a prism attached to a microscope to give the O blique illumination for observing very

L t - fine markings . a e ra l P . , an equal sided , total reflecting prism for illuminating a microscopic

field .

P rs - d o t r O i m i p y , n . In ptics , a standard deflection of a beam of parallel rays of light produced by m a prism . It is equal to 1 e . on a tangent plane s placed at a di tance of 1 m . b ehind the prism . To practically measure this deflection while

n looking through a prism or lens , and co s e quently upon a tangent plane placed in f ront of

th e prism , it is necessary to multiply these

dimensions by six , in order to insure parallel incidence of the rays constituting the beam of

- l ight . The prism dioptry establishes a definite r elation between the refractive powers of prisms “ - d n and lenses , since the prism dioptries in ece tered lenses are in direct proportion to their refractive powers and dec en tra t ie n ( see D ecen

- tration ) . The prism dioptry also bears a unique

LE W I S PO C KE T

i s an y pri sm that has the power to deflect a ray

'

f . o light 1 cm for each meter of distance .

These three methods of numbering prism s d iff er Very little for low degrees in op h th al m l o ogy . t Ro a t ing P ri s ms . If two prisms of equal s trength be placed with the base of one over

th e z apex O f the other , they neutrali e each

other , and if we rotate them in opposite direc tions we O btai n the eff ect of any pri smatic de

' g ree up to their combined values . A pri sm m for s no imag e and has no focus , and when l t ooked hrough , the eye turns toward the apex . D eato n P . , a prism attached to a m icroscope to give the O blique illumination for observing very

t - fine markings . La e ra l R , an equal sided , total reflecting prism for illuminating a microscopic

field .

P rs m-d o t r O i i p y , n . In ptics , a standard deflection of a beam of parallel rays of light produced by

a prism . It i s equal to 1 cm . on a tangent plane

placed at a distance of 1 m . b ehind the prism . To practically measure this deflection while t looking hrough a prism or lens , and couse quently upon a tangent plane placed in f ront of

th e prism , it is necessary to multiply these

dimensions by six , in order to insure parallel incidence of the rays constituting the beam of

- light . The prism dioptry establishes a definite relation between the refractive powers O f prisms “ - n and lenses , since the prism dioptries in dece tered lenses are in direct proportion to their refractive powers and decentra t i on ( see D ecem

- tration ) . The prism dioptry also bears a unique O PHTHALM I C DIC TIO N ARY 2 07

relation to the meter angle ( see M . The sign used to designate the prism -dioptry i s a

triangle . Thus the unit , 1 A of the dioptral sys tem i s distinguished from 1 ° of the old degree f system . S ince 1 89 5 American lens man u a c

turers have adopted the prism - dioptry as the

standard unit of prisma tic power .

’ m t - - i th e P ris a ic ( pris mat c ) . That which has

shape or efi ect of a prism . When a lens i s

decentered it will produce a prismatic effect .

’ r s m z- l a P i oid ( p ri moid ) . A body that resemb es

.prism in form .

’ P r o t mt - - - t- is p o e er (pris op tom e er) . ( Gr . prisma

prism op tos s een metron measure . ) An instrument used for testing the refraction of

the eye by means of a revolving prism .

P robe . A long, slender instrument for ex ploring

wounds . La c ri ma l P . i s a probe designed for

use on the tear passages .

’ P r l m - ob e (prob lem ) . ( Gr. problema a question

proposed for solution . )

' P rod -uk t r duc ere uct (prod ) . ( L . p o forward

to lead . ) The result from multiplying one

number by another .

P v M l rogres s i e Myop i a . yopia that is gradua ly on

the increas e .

’ P r hth l - l - op a mos ( prof tha mos ) . ( L . pro forward

z: op h th almos eye . ) A bulging forward or

undue prominence of the eyeball .

’ - - P ro rt o n . L rO Z b ef re p o i ( pro por shun ) ( . p o

portio share . ) A proportion is an expressio n

of equality of ratios . 2 08 LE W IS PO C KE T

’ ’ - - = . r r P roptos i s ( prop to si s ) ( G . p o forward +

ptosi s falling . ) A falling down or sinking of

a part .

P ros t es s . h i (Gr . in addition to to put ) The addition of an artificial part to supply that

which is wanting .

’ P ros t hes s O c r s - - i ula i (pro the sis ) . The Insertion f O an artificial eye .

P ot ra t r l L rotrah re c o S ca e . e r ( p to draw forth ) . A device for indicating the location of the axis

O f a cylinder lens .

’ P s e - -hl e - d b e s s . s d u o l p i ( seu do p sis ) (Gr . p eu es

- — l e i lz vi i n false l b p s s s o . ) That condition in which O bj ects look different from what they

really are .

’ ’ - - - - m , P s eudoglio a ( seu do gly oh mah ) . A circum

scribed collection O f pus in the vitreous .

’ - - - - . s P s oro phtha l mia ( soh rof thal mee ah ) ( Gr. p o

h 2 ros Scabby op ht almos eye . ) That in fl amma tory condition of the eye which is accom

n p a ied with itchy ulcerations .

' - - - = P t i ter x . e ryg um (ter yg i um ) . ( Gr . p y wing )

A thickening or growth of the conjunctiva .

’ having the appearance of a fl y s wing , usually

o n the nasal side of the eye , extending out

toward th e cornea . It can b e removed by opera

th e t ion , and should be as soon as it reaches

cornea , otherwise it will grow over it and i mpair

vision .

' - - te r x : win P t erygoid ( ter 1 g oid) . ( Gr . p y g +

- eidos resemb lance . ) W ing shaped .

LE W IS PO CKE T

opium or other drugs . A dilated pupil ( myd ria s is ) indicates eff ect of atropine or other

h rmetr drugs , myopia , amblyopia , absolute yp e o -

pia , glaucoma , or paralysis of third nerve . A a n is oc o ria . U nequ l pupils .

rect a . f Co o p i Displacement O the pupil .

Co rec lis i s . Closure O f the pupil by a mem

brane , which causes loss of visual acuity .

m r Co re o p ho s i s . The operation for artificial

pupil . The shape of the pupil is changed by syne

chiae , coloboma , iridodialysis , ruptures of the

sphincter muscle . The pupil appears black when no light returns through it to the eye O f

the O bserver . It is more dilated in youth than

in the aged .

’ r - - P P up ill a y ( p u pil lar ertaining to the pupil .

’ m t - — m - - r P o e e r u o et e . L u up ill ( p pil ) ( . pupilla p t pil Gr. metron measure . ) An instrumen

for measuring the diameter of the pupil .

L k eo P up i llos copy ( . pupilla pupil s op I

view) . S ee Retinoscopy .

’ t u- - - t- om - t- r L P up illos ta omet e r ( p pil o sta e e ) ( .

pupilla pupil Gr . s tatos placed metron

measure . ) An instrument to measure the

distance between pupils .

s i e Py rkin ges I ma ge . The mages seen on surfac

of cornea and lens . S ee Catoptric Test .

’ r m t - - - r z: P y o e e r ( p y rom e ter) . ( G . pyr fire met i ron measure . ) An instrument for measur ng

high degrees O f heat . O PHTHALM I C DIC TIO NARY 2 1 1

’ A D R I L T E L - - - - U A RA ( k w od ri lat e ral ) . ( L . qua

z - d tuor four latus a side . ) A four side

plane figure .

’ - - a t t . L ua n tus . Q u n i y ( kwon ti ti ) ( . q how much )

Any amount , in m easure or extent . zL = u . ua s i i in i iti n Q i ( q e t o q u s o ) . Instruction by

questions and answers . Q . Cl a s s , a body of stu dents forming a class for the purpose of being

questioned by a teacher . ( S ee last few pages . )

’ u t t - = Q o i en ( kwo shent ) . ( L . quotiens how many

times . ) The number resulting from the division

of one number by another .

’ - — : R AC E MO S E ( ras e mos ) . ( L . ra cemus a B bunch of grapes . ) unched ; clustered ; as in

staphyloma , where the bulging occurs in several

places .

' Ra di ra - a d ( de Towards the radial side .

’ R i - - a d a l ( ra de a l ) . O f or pertaining to the radius .

Ra dia n . An arc of a circle which is equal to the

radius , or the angle measured by such an arc .

’ - - t ra . L . Ra di a n ( de ant ) ( radiare to shine . )

Diverging , as rays from a center .

’ - - - Ra diation ( ra di a shun ) . Where rays O f light

appear to be thrown O ff from a common center .

Ra di us (L . The half of the diameter of

a circle . m Ra nge of A ccom odatio n . Th e distance of a p a

’ tien t s vision , or the range between the near

point and the far point of vision . 2 1 2 LE W IS PO CKE T

R a n ge of Vi s io n . The distance between the near

and far point .

’ R t r - a i o ( a sho ) . ( L from reri , ratus toreckon . ) The relation which one quantity or magnitud e

has to another of the sam e kind . It i s expresse d

by the quotient itself , m aking ratio equivalent

to a number . The term ratio is also sometimes applied to the difference of two quantities as

W ell as to their quotient , in which case the t former is called arithmetical ratio , the la ter

geometrical ratio . R atio of a geometrical pro

gre s s ion , the constant quantity by which each term is multiplied to produce the one suc

n ceedi g .

R t f l . a y. The smalles imaginary line O ight

Rec ro m r L i r n . i p cal N u be s ( . rec p ocus alternati g ) Two numbers which multiplied together make

unity .

’ Recta n e rek - - l L a n gl ( tang g ) . ( . rectus right

gulus angle . ) A quadrilate ral all of whose

angles are right angles .

Re t L c us ( . straight ) . Applied especially to cer

tain straight muscles .

R - e d B li n d n es s . That condition in which a person i s unable to distinguish red

’ - — Re du t n 2 c o re L . i ( duk shun ) . ( re back ducere z to bring . ) Changing the denomination of

. Reduct on As e n numbers i c ding , changing to a

higher denomination , as from 1 4 4 inches to 1 2

f Reduct De eet . ion s ce n di n g, changin g to a

lower denomination .

’ Ref e t i n re- fl ec z: — l c o ( (L . re back l fl ec

r: tere to bend . ) Throwing back light . R efl ec

2 1 4 LE W IS PO C K E T

e R . from th e perpendicular . Do ubl , refraction in which the incident ray is divided into two f refracted rays . S tati c R . , re raction of the eye

A 1 s if e mc rgc s

Y E SU F E RE F RAC T I O N B PLAN R AC .

1 ra f i h is a e d t h e in c id e n t b e f ore n t r i th e N O . y O l g t c ll e e n g o ra a s s in f r om a r a r r o a s e c n d m e d ium . A y p g e t e s r i ra t e d t ow a r d s t h r a r d n e m e d um is re f c e p e p e n d ic ul , T h ra B a s s h o w n in t h e a b ov e c u t . e y A is re f ra c te d on s t ri in a s s M M a n d a a in re r a t k g th e g l , g f c e d o n a r e m e rg in g . I n p a s s in g f rom d e n s e t o a r a r e r m e h r a f r om t h r ium t r a i r e f c t e d e e e n d i . d , e y s p p c ula r P re re s n a r f a in e r e n d ic u a r t o th e s ur a M p e t s a y ll g p p l f ce I t c on in u e s e p a ra t in g t h e t w o m e d ia . t s it s c ours e

w it h o ut un d e rg oin g a n y r e f ra c tio n .

2 re r e s e n t t h re fl e c t e d ra . T h e a n e f orm e d b N o. p s e y g l y t h e in c id e n t ra y w ith th e p e rp e n d ic ul a r is a l w a y s e q ua l i n t o th e a n g l e o f re fl e c t o . ' T h e d o t t e d l in e m a rk e d B A re p re s e n t s t h e co urs e th e N O ra w o a v t a e n h a d it n ot b e e n e r . 1 y ul d h e k r f a c t e d . T h e s id e o f t h e in c id e n t ra y m a rk e d B w ill b e f o un d a t R in t r e r a a h e e fl c ted a y , n d A t F .

D n m . at rest . y a ic R , refraction of the eye , plus

that secured by accommodation . Abs ol ute I n dex of Ref ra ct i on is that which is O PHTHALM IC DIC TIO NARY

found when light passes from a vacuum into a

given m edium .

’ Ref ra ct on s t re- - - n i i ( frac tion ist ) . O e who is skilled

in correcting errors of refraction of the eye .

’ Ref ra ct ve re - - P i ( frac tive ) . ertaining to refraction .

' R f ra t m t r r - k -t e - e c o e e ( e fra om ter) . An instrument

for measuring refraction .

' R la r re - - L egu ( g u lar ) . ( . r egula a rul e . ) Accord

ing to rule ; normal .

Relat i v e I n dex of Ref ra cti on is that which is found when light passes from atmospheric ai r

into another medium .

‘

Rela x ( L . re back l axa re to loosen ) : T o

loosen , to slacken .

’ R x t el a a io n . A lessening of tension .

R med L e . y ( re again mederi to heal ) . Any

thing acting as a cure for , or the relief from ,

‘ unhealthy conditions .

’ - - z- i a L . re os tus l Rep o s it io n ( re p O i shun ) . ( p to y l up . ) The act of putting back in a norma

position .

' - - L n O Ret ina (ret in a ) . ( . rete a et . ) n the inner

surface of th e choroid , and closely in contact

n d with it , w e find the internal or third a most

important of the ocular tunics , the retina ; to e rotec which , indeed , the other two are m er ly p

tive or containing membranes . Th e retina is the

n r wh ich immediate continuation of the O ptic e ve, .

erfo extends from the brain to the eyeball , p

rates the sclerotic and choroid , and immediately spreads out into a thin lam ina over the surface

of the latter , and is attached at two points only at the entrance of the optic nerve and at its 2 1 6 LE W I S P O C KE T

most anterior border , the ora serrata . The point of entrance of the optic nerve which is known , z as the optic disc , is nearly on the hori ontal

- f meridian of the globe , and about one tenth o

an inch to the nasal side of the posterior pole , so that h is the left ‘ eye which is represented in

E T I R N A . a — a a h os n iti r a m cul a l ute , t e m t s e s ve p a t o f th e re tin .

the cut under Anatomy . The function of the retina is to receive the pictures which are formed within the eye by m eans of the waves

of light reflected from obj ects , and , through the

medium of the optic nerve , to transmit the

resulting visual impressions to the brain . J ust as the sense of touch is not diffused uni

formly over the surface of the body , but is more — fi acute in some parts for instance , the nger

— tips than in others , so also the retina is not equally sensitive to the luminous impressions

over its whole surface , but in the highest de gree a little to the temple side of the posterior

n pole , i a part known as the macula lutea , or

yellow spot , which may be considered the real

center of the retina , yet it is to one side . F rom this spot the sensitiveness gradually diminishes

to its most anterior edge . The retina does not

2 1 8 PO C KE T

- light colored cloud before their eyes . But for the most part vision is very considerably re

duced , both because of the changes in the retina itself and because of the accompanying opac

ities in the vitreous . The course of retinitis is

always rather sluggish . It is only in the lightest cases that the infl ammation abates completely

within a few weeks , and then th e visual acuity

may once more becom e perfectly normal . B ut for the most part it takes several months for all the inflammatory symptoms to disappear from

the retina , while the sight remains permanently

. S impaired evere and , more particularly , recur rent in fl ammation s of th e retin a lead to atrophy

of it , pigmentation frequently occurring at the same time ( through migration O f pigment from

- the pigment epithelium ) . When atrophy O f the

retina has once made its appearance , the sight

is always destroyed , either completely or all

except a small remnant , and its restoration is

no longer possible .

’ Ret n o c - in -O - t i s o p e ( ret scope) . An instrument wi h which an objectiv e examination of the dioptric

state or condition of the eyes may b e measured .

( Made in plane and concave . ) The concave can b e combined with a strong

- h h a l 2 D . o t plus lens , about 0 , and used as an p f mos cop e . There is also a di ference in the move

m ent of the shadow in retinoscopy . In w orking

with the plane mirror between 5 3 and 60 inches ,

the movement is against in myopia of . 75 or a more , while in hypermetropia , emmetropi , or m less than . 75 of myopia the shadow oves with re the mirror . With the concave it is just the mmetro verse ; the shadow in hypermetropia , e O PHTHALM IC DIC TI O NARY 2 1 9

pia , and a small amount of myopia will go

against the mirror . In more than . 75 of myopia ,

th e movement will be with the mirror .

It makes no difference which you use . the

findings will be the same , and you deduct from plus and add to m inus findings the same amounts ; it depends on the distance you are

n e H a d R tinos cop e .

sitting from the patient . When sitting at a lit tle 4 over 0 inches , you subtract one dioptry from

all plus findings , and add minus . 75 to all minus

findings . Whe n working between 5 3 and 60

inches , you subtract . 75 from all plus findings

and add minus . 50 to all m inus findings .

’ Ret —ih - - - L s co eo s c co . ino o py (ret “os p y ) ( . retina p I examine . ) Skiametry . R etinoscopy , or

the S hadow Test , is one of the methods of esti

mating the refraction of the eye . We examine the movements of the shadow when the fundus is illuminated by light thrown into the eye from

a mirror . t W i h the Conca ve Mi rro r. The patient i s

seated in a dark room , with the light placed a

little above the head , and far enough back so

that it will throw no direct rays upon his face . It is best to use a shade around the light to prevent it from illuminating the walls of the

room , having a hole an inch in diameter in the 2 2 0 L E W I S PO CK E T

th h front and abou t e center of t e flame . We

will now begin with the examination . In examining the right eye have the pati ent

look across your right shoulder , and in exam ining th e left have him look over your left

shoulder . t O nce in a posi ion to begin the test , we reflect

the light from the mirror across several merid

’ ians of the patient s eye , at the same time watch

ing the reddi sh fundus reflex in the pupil . If the movement of the fundus reflex is against that

of the m irror in any one meridian , put a plus

sphere before the eye , and continue to increase its strength until you find the w ea kes t lens that

will reverse the last meridian , whose movement

was against that of the mirror . If there i s no astigmatism the reflex wil l be equally bright in all its parts like a small full

LE W I S PO C K E T .

tance we are holding th e mirror fro m the eye

of a patient .

x In writing the R , put down wha t is le ft of the sphere after deducting or adding for th e

working distance , combining with it the full

p ower O f the cylinder , placing its axis a t the degree the scratch on the lens points to on the

trial frame . If the above directions are followed plus cyl

inders will never be used . The larger the error the sl ower the movement

will be . Large errors are easier than small ones h to detect and correct with t e retinoscope .

P rove up your retinoscopic test subjectively . I f more plus can be added or less min us given h w ithout interfering w ith the vi sion , make t e

change . In using the plan e mirror follow above direc w t tions , but use plus when the shadow moves i h

a a s t and minus if g in . When the light that is coming from th e p a

’ tien t s eye (after reflection by the retina ) focuses in front O f the O perator the shadow will move

n w ith the movement of the concave mirror . O h th t e other hand , if these rays of light pass e

O perator without focusing , the movement wil l b e against that of the mirror

The shadow moves against in H ypermetropia , f E mmetropia and small amounts of Myopia . I " the O perator is working at 4 1 the eye must have one dioptre or more of Myopia for the s hadow to move with the movement of the

mirror .

O n page 2 2 3 are two cuts showing the fundus

reflex in the pupil . The reflex shows white O PHTHAL M I C DIC TI O NARY 23

instead of red as it really i s but they will answer the purpose ; the first i s round on the edge like

a full moon , indicating no sign of astigmatism , n while the second i s ribbon or band like , showi g there must be astigmatism between the 9oth 1 h and 80t meridians in this case .

’ - - Ret ra ctor ( re trac tor) . An instrument used for drawing and holding the parts away while

undergoing an operation , or for any other

purpose .

’ t r t - - - Re o bul b a r ( e tro bul bar) . (L . retro behind That which i s situated or

occurring behind the eyeball .

- Ret ro bul ba r N e uriti s . Inflammation of the op tic

nerve behind th e globe of the eye . 2 2 4 LE W I S P O CKE T

- v Re e rs a l P oint . Thi s term i s u sed ln reti n oscopy

to de scribe the change O f movement of th e

F or shadow . instance if the rays of l ight which are coming from the patien t ’ s eye focus behind the operator the shadow will always move against the movement O f the concave

mirror , if they are made to converge by th e

aid of a. plus len s so as to focu s just in front

of O the p erator, the movement will be with t h hat O f t e mirror , making it the point of reversal

R e r h h um ( ume) . ( Gr . r euma a flux . ) A watery

discharge from the eyes .

R e mat c r t s . h u i l i i Iritis cau sed by rheumatism .

’ h d o - - h od n = ros — R s . r r o e o p in ( rho dop sin ) ( G . l O z p S eye . ) Visual purple ; pigment O f outer

O f segment retinal rods .

’ t - - - w R d s id O . rin hy i o i s ( rit sis ) (Gr . rhytidosis a l kling . ) A wrink ing , as of the cornea .

Rio la n is Mus cl e . An involuntary muscle used in

e closing the y e. It reinforce s the orbiculars and brings the margin of th e lids closer to

gether .

o . c R d Relate s to the retina . It is one of the ell

' ’ elements of wh ich J a cob s Membrane is com

r u posed . These zmin te bodies are cylindrical in

o . . t m f rm , hence the t e r , rod ( rods and cones )

Rodent Ul ce r. A ( de structive ulcer beginning at

h ' t e margin of t he co rnea . It i s confined to the d B ’ surface , not g n ing eeper than owman s M r t des c M embrane . fFli s ( ribed by Dr . ooren .

’ Roe t e n . n m o f X n g Ra ys .A fin rays used in deter mining the p resence a n d also th e exact position h O f foreign b odieS iin lt e eyeball or orbi t .

2 2 6 LE W IS PO C KE T

D ioptries to cent imeters of focal length , divide

1 00 th e by number of dioptries . i Cent meters of focal length to dioptries , divide 1 00 by the number of centimeters . D ioptries to inches of focal length , divide 4 0

by the number of dioptries .

Inches of focal length to dioptries , divide 4 0

by the number of inches .

T o f d d t r c va ue of n in io p i l a y s urf a ce, multiply the diff erence of the index of refraction by th e number O f meter curves in the radius of curva ture and give it the sign O f the curve of the

denser m edia . R emember two meter curves in

- optics mean one half and three meter curves ,

- one third of a meter , and so on . T o find t h e a ngl e O f ref ra cti on , divide th e angle Of incidence by th e index of refraction of the

second media .

T o find t h e ra di us of c urvat ure of a n y medi a , , multiply the focal length desired by the differ

ence of th e index in the two m edia . - l n dex of Ref ra ct i on = Angle of Incidence di

v ided by Angle of R efraction . A n gle of I n c i d e n c e Angle of Refraction

multiplied by Index of R efraction .

Fo ca l Length of Cu rv ed mi rrors : one -half of

the radius . P ow e r of a Mi rror one meter divided by its

focal length ( catop tries ) . M et ri c C urve of a Mi rror one meter divided

by the radius of the mirror . Ra di us of Mi rror one meter divided by the

metric curve of the mirror .

T o fi n d t h e dio pt ry pow e r in any meridian of a e cylinder , take the distanc between the merid O PHTHALM I C DI C TIO NARY 2 2 7

I a n of which you wish to know the power and th e axi s of the cylinder , multiply it by th e

power of the cylinder , and divide by 90.

T O f n d t h e n umb e r of m met r i , illi e s t o d ec e n t e r a

e n s f or r s m t l p i a i c effect , multiply the prism wanted by 1 0 and divide by the power of the

lens . Wzhen prismatic effect i s wanted in b oth ' th e hori ontal and vertical meridians , one prism can a be used by placing prism obliquely .

T o f n d t h e r s m to re r i p i p s c i b e , square the power

of the original prism s and add . E xtract th e f square root O the sum , which will give you the

power of the new prism .

T o fi n d t h e me ri dia n to place the base of the n e w

prism , divide 9 0 by the combined power of th e original prism s and multiply by the vertical prism ; this gives the distance from horizontal

to place the base of the new prism . z T o find t h e s i e of t he ima g e , focal length of emergent wave multiplied by size of O bj ect

divided by focal length of incident wav e; or . dioptric value of incident wave multiplied by size of object divided by dioptric value of the

emergent wave . z T o find t h e s i e of t h e o bj ect, revers e the formula

above .

z th m n t h t n T o fi n d t h e s i e O f e i a ge o e re i a , multi ply the size of the object by the distance b e

tween the nodal points and the retina , then divide by the distance between the nodal point s

and the O bj ect .

T O fi n d c i rc umf e re n c e of a ci rcl e, multiply diam eter by 2 2 8 L E \ V I S PO C KE T

T o fi n d d ia met e r O f a c i rc l e , mul tiply circumfer

ence by . 3 1 8 3 1 . T f o in d a rea of a c i rcl e , mul tiply square of diam

eter by . 78 5 4 .

T O f d a r t in ea of a ri a n gl e , multiply base by one

half perpendicular height .

T o fi n d s urf a c e of a b a ll, multiply square of diame ter by

R U L ES T O BE RE M E MB E RE D

N 1 N w t O . . O o o , eye sh uld be allo ed use

accommodation at 2 0 feet or more .

No . 2 . Always give a hyperope th e stron gest t t p lus hat will not blur his best dis ant vision . 3 No . . Give a myope the weakest minus tha t

v w ill give him best vision . Ne er put minus it where does not show returns . 4 i . l No . After putting the patient l th e fog . place the axis of your minus cylinder a t ri gh t

a ngles to the plainest line seen . N ft O . 5 . Correct presbyopia a er correcting

distant vision . B N O . 6 . efore testing for mil s cle trouble cor

rect the ametropia .

L s - AC ( . accus a bag ) . A bag like organ .

’ ’ S - - z a em i s c h s Ul c e r is a mish e ) . ( E dwin Theodor S aemisch . Australian ophthalmologist ,

Infectious corneal ulcer .

’ S a r s r- k - r c om a ( a o mah ) . ( Gr. s a x flesh oma = tumor . ) A tumor made up of a sub s ta nce

like the embryonic connective tissue . I t i s

O ften highly malignant . S arcoma o f th e ciliary

2 30 L E W I S PO C K E T

’ - - - t t s L . S c i n ill a ion ( cin til la shun ) . ( scin tilla a

. t f s f th e spark ) A sensa ion o parks be ore eye .

h S c i s s o rs Mo v e me nt . A peculiar movemen t of t e

t th n s t re inal reflex , resembling e opening a d hu t t ing O f a pair of scissors . I t indica es a condi

tion of irre gular astigmati sm .

' - ( k t- k . l r w . T S c l e ra a le ra ) (Gr . s e os ha ) h e ex l t t th h terna and whi e coa of e eyebal l , t e s ole ti ro c .

P S e r . t th e c l a l er aining to sclera .

’ ( k - - - - ( r k G . s S cl e recta s i a s l e rec ta si ah ) . clera e z t t h ta s ia a n exten sion . ) A bulging s a e of t e

s clera .

' k - - ( k S c l e rect omy ( s l e rek to Gr. s l e ros

: hard ek tome excision . ) E xci sion O f a por f tion O the sclera .

’ S c e re ta s skl e - - - t O f th e l c is ( rek ta si s ) . A pro rusion S s t . S ee clero ic coat taphyloma .

k - - fi - k r S m l i m . c l e ri rito y ( s e rir t o y ) ( Gr . s l e o s

s o h hard iri s tom e excision . ) Inci ion f t e t s clera and iri s in anterior S aphyloma .

’ - - k 4 t ( s k l e . Gr l e ros i s S c l e ri i s ri ti s ) ( . s hard ti

inflammation . ) Inflammation O f th e s cl erotic

coat .

’ - - - - I S c l e ro c ho roi dit i s ( s kl e ro cho roi d i tis ) . n fl a m mation O f both th e choroid and th e s clerotic

coats of the eye .

’ k - - - - - v t S c l e ro conjun cti v a l ( s l e rO con junc ti a l ) . Tha condition in which th e sclera and th e con jun c

tiva are concerned . w S c l e ro c o rn ea l S uls us ( furro ) . The angle or de pres s ion formed by th e di fference i n th e radius

of curv ature of the sclerotic and cornea . This O PHTHALM I C DIC TI O NARY 2 3 1

angle makes the eyeball stronger and more fi rm t at this poin , and it is just inside thi s angl e tha t

the ciliary muscles are attached .

’ - - - - S cl e ro c o rn ea l ( s kl e ro cor n e al ) . R elating to the

sclerotic coat and cornea .

’ - ~ - - S cl e roi ritis ( s kl e ro i ri tis ) . An inflamma tion

which involves both the iris and the sclera .

' k t . s S c le ro e ra toi ri i s Inflammation of the clera ,

cornea , and iris .

‘ ' S c e r x kl - ro- - Gr k r z h rd l ony i s ( s e nyx is ) . ( . s l e os a

: + n yx is a pricking . ) A perforation of the

sclerotic coat .

’ S e r m kl - - - - k c t a a s e a . s l e l o ph h l i ( rof thal mi h ) . ( Gr

ros hard op h th al mos eye . ) That condi

tion in which the sclera overlaps the cornea , so

that only a portion of the latter remains cle a r .

’ S c r s e kl ro l e o d ( Gr . s e s hard ) . That condition in which a part is a ffected with sclerosis ; a

hardening .

’ - = l r k . S c l e ro s i s ( s c e O sis ) . ( Gr . s l eros is hardness )

in The process of becoming hard , tough , or

dura ted .

- - = S r t k k . c l e o ic ( s l e rot l o) . ( Gr. s l eros hard ) The

- posterior fi ve sixths of the first tunic . It is

firm . hard , and opaque ; known as the white of

v the eye . It serves to gi e shape to the globe ,

th e protects its more delicate interior , and at

- t is same tim e acts as a dark box or camera . I

t Th e o this coat that the muscles a re attached .

sclerotic is thickest in the posterior part , where

it has a thickness of about 1 mm . It gradually diminishes in thickness toward the anterior

part , becom ing somewhat thicker near the cor LE W I S PO C KE T

nea , because here th e tendons of the recti

’

muscles are attached a n d fus ed with it . The sclerotic c onsists of fine cotton-like fibers or

connective tissues , W hich are united into bun . i dles which seem to b e woven i n all d rection s .

B - etween the bundles are found lymph spaces ,

which are in part lined with fat cells . The

- sclera has very few b lood vessels and nerves . The blood -vessels are derived from the anterior

c iliary and posterior ciliary arteries . The venous blood is removed by the vena e vorticosae and

the anterior ciliary veins . Its nerves are de

rived from the ciliary nerves .

’ kl r~ - i- - - m r s k l e G . S c l e roti c ectomy ( s e ot kek to y ) . ( k t ros hard e tome excision . ) An opera ion for artificial pupil by removal of a portion of

the sclerotic .

’ k l - - - kl eros = h ard e r t s e . s S c l o omy ( rot O m e) (Gr . S urgical incision of the

sclera .

- r k otos S coto dini a ( sko to ( G . s dark D zz ness dine a whirling . ) i iness , with head

ache and dimness of vision .

’ - - k m k . S cotoma ( sko to mah ) . ( Gr. s oto a dar ness ) That condition in which there is a blind or par

s tia lly blind area in the visual fiel d . S ometime

the patient will complain of seeing dark , vanish

b s ut e S . in g , cloudy spots before the eye s . A ol , a part of the visual fi eld in which there i s absolute

blindness .

' - - — S c otomet er ( sko tom e ter ) . An instrument for

measuring scotoma .

is Gr. k s t S e ba c eou s Cy s ts ( L . sebum suet y “

bladder . ) A small rounded body , the size of a

2 3 4 LE W I S PO C KE T

s r l p e ica and convex cylindrical lenses . The sign O f subtraction is used to represent concave spherical and concave cylindrical

lenses .

L = S n e . . s in in i ( us s e . ) The length of a per p en dicula r drawn from one extremity O f an arc O f a circle to the diameter drawn through the

other extrem ity . S ine of an angle is a circl e t whose radius is unity , the sine of the arc tha

- measures the angle ; in a right angled triangl e , the side O pposite the given angle divided by th e

hypotenuse . Versed sine , that part of the diam

eter between the sine and the arc .

’

t . . S i n i s ra d ( Gr . sinister left ad to ) To or

toward the left .

’ - S L . . i n us ( si nus ) . ( gulf . ) A hollow cavity

F ro n ta l S in us , one of the two irregular cavitie s in the frontal bone containing air and commu

n ica tin g with the nose through a funnel - shaped t passage . O cc i p i a l S in us is the smallest of the

cranial sinuses , occasionally there are two . It is situated in the attached margin of the falx

cerebelli , opening into the torcular H erophili .

La t e ra l S i n us , two veins of the dura running

along the crucial ridge O f the occipital bone .

C a v e rno us S i n us , venous cavities , starting b e

hind the sphenoidal fissure , running back on the

side of the pituitary fossa , and joining the s u

perior and inferior petrosal sinuses . E ach cav

e rn ous sinus receive s anteriorly the superior

ophthalmic vein through the sphenoidal fissure . on the inner wall of each sinus is the internal

r t d corotid artery , filaments of the co o i plexus .

abducent nerve ; and on the outer wall , the O PHTHALM IC DI C TIO NARY 2 3 5

trochlear , ophthalmic , oculo motor and the m axillary division of the trigeminal nerves .

’ k - - = S a s c e r. k i i o p ( ski as kope ) . ( G s a sh a dow k s op eo I examine . ) B etter known as the

retinoscope .

k r — k S i a sc o p y. ( G . skia shadow l s op eo I ex e S ee R amin . ) etinoscopy .

M . D . P . S n ell en , , rof H . B orn in H olland . A pro fes s or of O phthalmology occupying the chair a t

e - the Univ rsity at Utrecht , H olland . A p upil of D F . . r D r. C onders , whom he succeeded in p a c

tice and hi s professorship . H e devised a chart consi sting of letters and symbols by which the s ubj ective means of measuring the range of vision coul d be uniformly and scientifically de

t ermin ed . It i s held by S nellen that in order to distinguish one letter f rom another the eye must be able to disting uish the spaces between the

lines which correspond to a . visual angle of f r e This i s true for certain letters , as , o instanc . 0 to differentiate between and C , where the eye

S n e e n C h a rt ll .

mus t distinguish the white space which inter

ru ts p the circle in C . The same is true for E F l and , but the principle is not app icable to th e other letters of his series . In a lecture on L E W' I S P O CK E T

f re raction by L andolt , we l e a rn of what great advantage it is to determine th e visual acute~

a n d t ness h e refraction at the same time . We must determine the refraction at such a di s tance as shall exclude the accommodation as

‘ a s os s ibl r t much p e . F o this a distance of twen y t f feet , or six metres , i s necessary . We here ore 2 t h place our test type at 0 F , and see wha are t e

smallest characters which each eye , separately ,

n can distinguish . These types are so desig ed that at the d istance at which they should b e

’ seen they each subtend an angle of 5 at the eye . l And when the etters marked 2 0, or 6 M , are

read from 2 0 F , vision is said to b e normal , and an eye with normal vision can read any of th e letters on the chart at the distance at which t hey are marked .

- S n ow bli n dn es s . L ong exposure of the eyes to the glare from snow gives rise to an acute con jun c

tiv itis , attended with intense pain , photophobia ,

and occasionally conjunctival hemorrhages .

’ k - = S t . c e . L o ( sok ket ) ( . soccus a show , a sock ) A hollow part into which a corresponding part

fits . = ; s a s m s I . S p a s m (L . p u draw ) An involuntary

contraction O f a muscle . S pasm of accommoda tion is a spasmodic contraction of the cil iary f th muscles , thu s increasing the convexity o e crystalline l ens and making the eye appear to

have a higher refractive power . There are two

— kinds tonic and clonic . T oni c s . is where th e t spasm persists for a considerable ime , and

s t a C loni c s . is where the muscle con r c t and re

lax intermittently .

2 3 8 LE W IS PO CKE T

f . r S p h e ri ca l . H aving the form o a sphere S p h e i c a l Lens is one the curved surface of which is a segment of a sphere and is known as a lens with the same re tra ctin g power in all its

meridians . There are three ways to grind a plus or m inus sphere of the same value ;

- - namely , b i concave , plano concave , periscopic

b i- - concave , convex , plano convex , periscopic

convex . S ee L enses .

’ - . s h a ir S p h e roi d ( s p h e roid ) ( Gr. p a sphere

eidos resemblance . ) That which resembles a

sphere in shape .

S er et er. h a ira z p h om ( Gr . s p sphere metron h measur e . ) An apparatus for m easuring t e

curvature O f a surface .

’ t - h in c . r S p hinc e r ( s p ter ) ( G . sphinkter a band . )

n s k A ri g li e muscle . The sphincter muscle of

the iris when contracted closes down the pupil . When rel axed allows the pupil to becom e

dilated .

’ t r m - - in th r S p in h e i s ( spin ther ism ) ( Gr . s p e

spark . ) That condition in which the patient

- complains of seeing star like flashes of light .

’ - kw S . S q u a mou s ( s a mus ) . caly

k r L t r r ou . S qu a e ( s wa ) . ( . quatuor ) ( a ) An

equilateral rectangle . ( b ) The second power of

a number . ( 0 ) To raise a number to the second

power .

F r. S q uint . ( guigner to wink or direct with one

eye . ) The act of h a l f closing the eyelids while

viewing an object . The word squint is som e t imes used to denote strabismus .

’ - f - - S ta p hylom a ( sta y lo mah ) . ( Gr . staphyle m = tum r grape o a o . ) A bulging of the cor O PHTHALM I C DIC TI O NARY 2 3 0

t e r s . nea or sclera . An rio , a bulging forward o f

th e an terior portion of the eye . P o s t e rio r s . , backward bulging of the posterior pole of the

eye .

’ k = in S tat i c (Gr . s ta ti os ca us g to stand . ) N o t

in mo tion ; in a s tate of re s t. The s tatic re trae tion is the refraction of th e eye w i th the mus cles of accommoda tion at rest ; just the rever s e

to dynamic refrac tion .

’ Gr Steato s i s . ( . stear ( steat ) tallow suffi x

z; o s i s condi tion . ) That condition in which we have fa tty degeneration ; disease of the s eb ac e

ous glands .

' S - - - i G r s S te a c o a c . no p i lit ( sten p ) ( . tenos = n n narrow O p e o p e i g . ) An acce s sory to be

found in any complete trial case , and consists of an opaque d isc w i th a slit about an inch long

a n d one millime tre w ide . I t i s used for the pur po s e o f finding th e principal meridian s in case s

f s s o f regula r a s tigma ti s m . i vi ion i near nor ma l it is be s t to fog or blur it a line or two wi th

a plus s phere . then place the d i s c in the trial 2 107 LE W I S PO C KE T

fra me in front of the eye we are about to ex h amine , while t e other is covered by the opaque

disc . Instruct the patient to revolve the disc in the trial frame while trying to see the letters

’ on S nellen s test type a t a distance of twenty fee t ( never th e astigmatic W heel ) and stop when

th e t t best vision i s ob ained , hus locating the i p r ncipal meridian with least error . We then n ote the degree mark on the trial f rame to which the slit is pointing and make a right angle c ross on a piece of paper showing thi s meridian

a n d the one at right angles . We now proceed to correct the error by placing spheres over the s lit until we find the strongest plus or weakest

minus that allows the best vision , writing the amount on the arm of the cross corresponding to n 9 0° the slit . The revolve the slit and fit this

meridian as above , writing the amount on the

other arm of the cross . F rom this cross we

write the Rx without any change . Thi s will

re present the Ametropia .

’ - - - ) S t e reo s c o p e ( ster e o scope . ( Gr . stereos sol id I V n s k op eo iew . ) An i strument composed of two prism s arranged in such a way that two

‘ s eparate pictures of the same kind may be seen i as one . This in strument makes the p cture

more natural , as the objects appear to stand

out .

V n - - - -l o S te reos c op i c i s io ( ster e o scop ) . Where we have equal vision with the two eyes and the

objects appear to stand out in solid form , and

are not seen as flat pictures .

’ S t n s a n a . B S i G illi g C l ( enedict till ng , erman anato A mist , 1 8 1 0 small canal leading from

2 4 2 LE W I S P O C KE T

‘

turn the eye with the error to one side . Alt er

. t na ting s , affecting bo h eyes equally , but not at

im . the same t e Co n co mita nt s . is that form of G

strabismus in which one eye , although deviated ,

always moves with the other , so that the

r tu n in g in .

B o h E e s turn i t y n g in .

r B oth E y es tu n in g out.

amount of deflection remains the same . P a ra l t ' y i c s . is due to paralysis of one or more of th e

extrinsic muscles , and the eye remains station

ary . H ypermetropia is responsible for 8 0 per cent of convergi n g strabismus on account of the ciliary muscles and the internal rectu s O PHTHALM I C DI C TIO NARY 2 4 3

‘ muscl es b e in g s up p l ied by on e and th e same

nerve . When the eye attempts to accommodate in

o h rmetr 1 th e in order to overc m e the yp e op a , .

ternal rectus will contract , and if the patient has not th e n erve energy to control th e external

rectus , the eye will turn in . S ee H eterotropia .

’ S t ra bot m - - o-m o y ( stra bot y ) . ( Gr . oblique “ : tome a cutting . ) An operation calling for the cutting of an ocular tendon for relief in cases of

strabismus . . z S t r in . L trin r a ( . s g e e to bind . ) Injury from

- us e . r over C ili a y s . , the result of overwork of the ciliary muscles in hypermetropi a and some

times in emmetropia. Mus c ul a r s . , overwork of

the extrinsi c muscles a s in heterophoria .

Reti n a l s . , fatigue of the retina caused by too

- strong light or from over use in a normal light . The eye should b e protected from a ll direct

rays of light , as only reflected light is n eces

sary for vision .

’ - S troma ( stro ma ) . ( Gr. I spread out . The

foundation tissu e or support of a formation . “ ” S tye ( to rise ) or Hordiolum. A s mall boil af fectin g th e connective tissu e n ear th e edge of o the eyelid , sometimes several appear at nce ,

or there may be a s uccession of them . They

cause swelling of the lid . I n a day or two the

swelling increases , with considerable pain , and

the Skin over it becomes red , afterward s show ing a yellowish discoloration at the center that a finally opens near the border of the lid , with

r n discharge of pus . Afte which the i flammatory

symptoms abate and th e cavity soon closes . 2 4 2 LE W IS P O C KE T

'

turn the eye with the error to one side . Alt e r

. f na t ing s , a fecting both eyes equally , but not at

. t the same t ime Con com i a nt s . is that form of

strabismus in which one eye , although deviated ,

always moves with the other , so that the

t urn in g in .

B ot h E e s tur n i y n g in .

t E s turn in B o h y e g out.

amount of deflection remains the same . P a ra

t - f Iy i c s . is due to paralysis of one or more o the

extrinsic muscles , and the eye remains station r ary . H ypermetropia is resp onsible for 80 p e cent of converging strabismus on account of the ciliary muscles and the internal rectu s

LE W’ I S PO CKE T

Treatment : S mall poultices or hot fomenta

tions until pus forms , then open by incision

parallel to the edge of the lid . General health

requires attention if eye strain is not the cause .

’ . L S uba ra c h n o d S a ce . i p ( sub under Gr .

arachne cobweb e i d o s resemblance . ) That space between the dura mater and the pia mater which forms the optic sheath and the

Capsul e of Tenon .

’ t - - - - S ubc on j un c i va l ( sub con junc ti val ) . That which

i s situated just beneath the conjunctiva .

’ S t - - ubj ec iv e ( sub jec tive ) . That which pertains i to , or i s perce ved by, an individual . Not per l c ep tib e to any other person . It refers to the patient as he sees objects or feels concerning

his own impressions .

’ ’ b t R t n t = S u l a io e i a e . (L . s ubla us taken away

rete net . ) Detachment of th e retina .

' b uxa t on . L l x r S u l i ( . sub under u a e to dis

locate . ) Wh ere the lens of the eye is a little

displaced , subluxation may consist in the lens

n being turned a little obliquely , so that one e d

of it looks somewhat forward . This condition may be recognized from th e unequal depth of

the anterior chamber . In cases of luxation ,

that is , where the lens h as left its place in its ’ t capsule , so that it partly covers the pupil , tha part of the pupil which is a deep black has no

s lens , while the part which contains the len

would b e of a delicate gray . Any dislocation of the lens entails a considerable disturbance of

vision . If the lens s till lies behind the pupil the

eye becomes very myopic , b ecause the lens i s allowed to assume its maximum convexity on O PHTHALM IC DICT IO NARY 2 4 5

account of separating from the suspensory liga ments which keep it elongated when the eye i s

at rest . Invariably any tear in th e s us p e n

sory ligament results in soft cataract . Added

to this is a considerable degree of astigmatism . D isloca tions of the lens usually entail second ary consequences which may be extremely dis

astrous to the eye , but in those cases in which the dislocation entails no further injurious con

sequences than the disturbance of vision , the treatment consists in prescribing suitable

glasses .

’ - - S ubo rb it a l ( sub or bit al ) . Beneath the orbit .

’ - -in - a b e S ub reti n al ( sub ret al ) . S itu ted neath th e

retina .

’ — r - - L 2 S u bt a ct i on ( sub trak shun ) . ( . sub under l

trah ere draw . ) The operation of finding the

di fference between two numbers .

’ - - - v t vo l n . L S u b olu ion ( sub shun ) ( . sub under

v r z th r olve e to turn . ) An operation for e e

moval of a pterygium .

- = A S uction ( s ud shun ) . ( L . s ug ere to suck . )

method by which fluid i s withdrawn .

’ - -z L uff n d r S f us tu h un . s u e e u f ion ( suf ) . to pour

- down . ) S tate of being blood shot , or of being

°

moistened . A suffusion of tears is an excess o f

th e flow of tears .

L — U . . S up er C ili a . ( pper hairs ) ( super above l

cilium eyelash . ) The eyebrows .

’ - - - - - S up e rcili a ry ( su per cil i a ry ) . That which per w tains to the eyebro .

S r r da S a c e up a Cho oi l p . The space between the

scl erotic and choroid . 2 4 0 LE W I S P O C KE T

S u r d t : L . p a uc io n , S urs um v erge n c e . ( sursum up f ward vergere to bend . The act or power o

t its urning one eye above fellow .

' S ra rb ta l su- - or -b i- u p o i ( pra tal ) . (L . supra above

orbita orbit . ) L ocated over the orbits .

- S up ra o rbita l Fo ra me n . A small passage in th e S upra -orbital R idge through which passes the supra -orbital nerve ( a branch of the fifth )

artery and vein .

’ S urface - L u rfi i ( ser fas ) . ( . s p e c es the upper

face . ) The bounding or limiting parts . of a solid .

’ S r t - - k - u s um du c io n ( sur sum du shun ) . (L . sursum

upward d ucere to draw . ) The act of turning one eye upward independen t of its fel f l ow . The test is made by placing the base o t h e prism down until we find the strongest

which the eyes can see an obj ect singly . It i s seldom more than 3 °

' S urs ver e n ce - - - en z L um g ( sur sum vur j ) . ( . sursum

z —- r r z up wa rd l v e g e e to turn . ) An upward

turning of the eye .

’ - - - L S urs umv ers i on ( sur sum vur shun ) . ( . sursum z = up ward + vertere to turn . ) The act of

turning the eyes upward .

’ - - - r L s us en dere z to S us p ens o ry ( sus pen s o y ) . ( . p

suspend . ) S erving to hold up a part .

n S us p e n s o ry Li ga m e ts . The hyaloid membrane f orms the hyaloid sac in which the vitreous

h umor is contained . It runs forward up over s us en the ciliary body , divides and form s the p

sory ligaments , which are attached to the lens L t capsule . C . B . ockwood , in a journal of Ana

- m P I . E d . o y and hysiology, vol . X X part of

2 4 8 L E W I S PO C KE T

faction of the vitreous . When observing opaci

t th e ties of the vitreous wi h ophthalmoscope , we see that most of them float about freely in

the vitreous . F rom this we would assume t hat — the framework of the vitreous must have been

destroyed , so that this body itself is converted

into a perfectly liquid mass .

’ n d m z n S yndes mi ti s . (Gr . s y es os ligame t itis

inflammation . ) That condition in which there i s inflammation of a ligament or of the

conjunctiva .

’ - - - Gr n i 2 . s ch e a c n S yn ec hi a ( syn e chi ah ) ( . y e o

. u . tin uo s ) Adhesion , as of the iris to the lens

P t r r . th . e s e or cornea os io , adhesions of iris to

the lens capsule . A n t e rio r s . , adhesions of the

iris to the cornea .

’ - - - z ize . Gr . Con S yni es i s ( sin sis ) ( . a falling in

traction of the pupil of the eye .

’ - - - S y n o p htha lmus ( syn of th al mus ) . ( Gr . syn to

- gether op h th almos eye . ) A one eyed mon

ster .

' - - k s n z to eth er S ynt ro p i c ( sin trop i ) . ( Gr . y g k direc trop i os turning . ) Turned in the same

tion . = m to . S y s tem . ( Gr . sys te a place together ) A An of bodily organism . assemblage parts or _

organs Which unite in a common function .

0 An abbreviation for tension or temperature . T ’ a n ge nt ( tan ( L . tangere to touch . ) Touching at a single p oin t f s p ecifica lly m eeting a curve or surfac e at a point and having a t that O PH THALM I C DI C TIO NARY 2 4 9

' point the same direction as the cur ve or sur — face said of a straight line , curve or surface ;

as , a line tangent to a curve ; a curve ta ngent to

a surface ; tangent surfaces . Tangent plane i s a plane which touches a surface in a point or

line .

’ - - T t m . a e u e L . p ( ta p tum ) ( . a carpet The

luminosity seen in the eyes of many beasts . A “ h lustrous , greenis membrane seen in the eyes of cats and many animal s that require night

vision .

’ ’ T rs a rt - - - - a a a e il . l C il g s (tar sal kar t aj es ) . ( Gr

ta rs os : a wicker work fram e + cartilago

gristle . ) That which forms the tough skeleton

layer of the eyelids , giving them rigidity o f

nd rm form a affording them fi support . Th e shape is like that of the lids being fastened

around the edge of the orbit . The tarsus of the

upper lid i s broader than that of the lower .

’ - - T t i . r a rs i i s ( tars tis ) ( G . tarsos a wicker work

fram e itis inflammation . ) An inflammation

involving the tarsal cartilages .

’ t - - - t T r a s o . l a s o pl s y ( tar plas y) ( Gr . tarsos p a s s o

I form . ) P lastic surgery of the tarsus .

’ - - -f T s r a a e . a r or h p hy (tar sor ) ( Gr . tarsos rhaphe

a stitching . ) An operation upon the eyelids .

’ r - - - Gr. Ta s otomy (tar sot o my ) . ( tarsos tome

incision . ) A surgical operation which involves

the cutting of the tarsal cartilages .

’ - r r = T a rs us ( tar sus ) . ( G . ta s os a wicker work

fram e . ) That which form s the skeleton of the r f it eyel id , givin g it rigidity of fo m and a fording

firm support . The tarsus of the upper lid is

broader than that of the lower . 2 5 0 LE \ V I S PO C KE T

T ea rs . The watery secretion of the lacrim a l

glands .

’ T e c s - - - i hop ia ( tei kop si ah ) . ( Gr . teich os wal l o i p s s vision ) . A luminous appearance before

‘ - the eyes , with a zigzag, wall like outline .

’ T e a n e t - n - - k - - l gi c a s i s ( tel a je e ta sis ) . ( Gr . telos end an g eion vessel ektasis a stretch

ing out . ) D ilatation of capillaries .

’ T e n n - - de cy (tend en cy ) . A dispos ition on the part

of a muscle to incline toward certain directions .

’ T - = e d n . L en n o ( ten don) ( . t do l stretch . ) The fibrous cord s by which the muscles are

attached .

T n n S e do s ( inew . ) White , glistening , fibrous

cords , varying in length and thickness , some

times round , sometimes flattened , of consider

able strength and devoid of elasticity . Apon

- euros es are flattened or ribbon shaped tendons . They are without nerves and have very few

- blood vessels . Tendons pass through all mus

cles and form their attachment at each end . Tendon of L ockwood gives origin to the S uperior Internal and upper head of the E x

ternal recti muscles . It is part of the ligament

of Z inn .

’ T - - - = n n e n on it is (ten ou i tis ) . ( Gr . ten on te do

n . itis . ) Inflammation of th e Capsule of Teno

’ ‘ T e n n s s l . J F o C a p u e ( acques Tenon , rench anat

mi 1 2 4 . o st , 7 ( Tunica vaginalis oculi ) The

cup - like thin membranes which envelop the eye

ball , covering the sclera from the optic nerve to b the ciliary region , where it joins the ocular s u

conjunctival tissue . The space within the orbit

L IQW' I S PO CK E T

t T t rial . . yp es , letters of various shapes and z in si es used testing vi sual power .

’ T t i t t- - - - e ra n o s a e o a . Gr p ( ran p si ) ( . tetra four 4 a n o s is away p vision . ) O bliteration of

- one fourth of the visual field .

’ T e rm meter - - e- h o (ther mom ter ) . ( Gr . therme

heat metron measure . ) An instrument by

which temperature is measured .

’ ha a us - - T l m (thal a mus ) . ( A room ; a bed . ) Th e t l place in which a nerve originates , O p i c Th a

a mu s . A mass of nerve matter on both sides of t h e third ventricle of the brain .

’ r - - = Th o mbo s is ( throm bo sis ) . ( Gr . thrombosis a

- . t curdling , a clot ) The formation of a blood clo

i n a vessel at the point of obstruction .

’ - r th reos T hy roi d ( thi roid ) . ( G . y an oblong

- m . . shiel d eidos for . ) S hield shaped T Gl a n d is a vascular body situated at th e front and

s i de s of the neck , and extending upwards upon

each side of the larynx . It is a single gland ,

varying greatly in size in di fferent individual s .

T in ea T a rs i . Blepharitis marginalis . S e e Bleph

a ritis .

To b a cc o A ma u ro s i s . ( Gr. a ma uros obscure . ) A d imness of vision caused by the excess ive use th of tobacco , which acts directly upon e nervous t system . The reduction in the visual acui y i s

al mos t always the same in both eyes . Treat f m ent consists , first of all , i n abstinence rom t tobacco , and it i s probable tha in light cases f thi s alone i s sufficient to e fect a cure . “ r —— T onic S p a s m . ( G . tone l to A con tin uous involuntary contraction of th e ciliary O PHTHALM I C DI C TIO NARY ass

muscles . Thi s condition may exist in any

muscle .

’ T ete r to- - - onom ( nom e ter ) . ( Gr . tonos tone

: metron m easure . ) An instrument for meas

uring the tens ion of the eyeball .

T o ri c Le n s . A lens with a sphere and a cylinder

on the same side , usually periscopic in shape .

S ee L ens .

’ - T rs . L tor r o ion (tor shun ) ( . q ue e to twist . ) A

twisting . k z i x . . A T o i c Am blyo p i a ( Gr tox i on p o s on . ) m

bl yop ia caused by a poison , a common cause

being excessive use of tobacco or l iquor or both .

’ - - : k . r tr h T ra chom a (tra o mah ) ( G . a c ys rough . )

Granular Conjunctivitis . Characterized by slowly progressive changes in the conjunctiva

of the eyelids , in consequence of which this

m embrane becomes thickened , vascular , and

roughened by firm , round elevations , instead of

. G being pale , thin and smooth ranular disease t is very importan . because it greatly increases th e susceptibil ity of the conjunctiva to take on acute inflammation and to produce contagious

d ischarge . It often gives rise to deformities of

the l id and to serious damage of the cornea. The conditions which favor the development and spread of trachoma are unclean and over crowded surroundings in which ventilation is

neglected , and the locality i s dam p . The disease i s common among school children wh o are

poorly nourished .

t . T ra ct . S ee O ptic Trac

’ - - : T ra ns ect ion (tran sek shun ) . ( L . tra n s a cros s 2 5 4 L E W IS PO CKE T

sectio ; secare to cut . ) A section mad

across a long axis .

' Tra n s ill umin at io n ( trans -il - l n - min - a - shun )

trans through illuminare to light up . The inspection of the interior of an organ b

means of a strong light .

T ra n t L s i . ( . trans through . ) A passing across A term used in retinoscopy to indicate move

ment of the light area .

’ T r a n s i tio n a l Zo n e . The posterior part of the len

sac during the stage of growth .

’ T a n L r s l u c e n t . ( . trans through lucere

shine . ) The quality of transmitting rays of ] without the obj ect being distinctly s F ( rosted glass . )

T r r L a n s p a e n t. ( . trans through parere t

appear . ) H aving the property of being clearly

seen through .

’ T a s s t n - - - L r n po i io (trans p o si shun) . ( . trans a cro s s n r = t + p o e e o place . ) Changing the form of an optical prescription without changing its optical value To transpose a lens is to change its curves without changing its refrac

tive value. To transpose an optical prescription is to change the form or shape of the lens without

f b e changing its optical value , periscopic e fect ing the prime and important feature in most

instances . The term periscopic i s applied to

- lenses having concavo convex surfaces , which enable the eye to view with equal likeness on

d s cri all sides . When lenses are not of thi s e p tion the desired result may be obtained by the following rules

2 56 LE W I S P O C KE T

A E m 2 . xa pl e, 3 s p h . cyl ax . 60. A 2 e 1 h . . . Answ r , s p cyl ax 1 5 0.

A E xampl e, 2 s p h . 2 cyl . ax. 9 0.

4 2 . h . 1 8 s . 0. Answer, p Q cyl ax

- E 4 2 . . 1 . 4 5 3 5 xample , cyl ax . 3 l cyl ax .

A 2 . 2 . 4 Answer , s p h cyl ax . 5 .

2 . E . . . 1 1 3 0 3 0. xample , cyl ax c cyl ax

A h . . Answer, 3 s p 6 cyl ax . 1 1 0.

E xample , 1 cyl . ax . 60.

1 s h . l . 1 5 1 c . 0. Answer , p C y ax Writing a prescription from a cross is not

transposing . We must first have a written pre

s cription before it can be transposed . In order to give the patient glasses which

”

give them the best possibl e results , it will be necessary to know how to build lenses of dif

feren t shapes , for instance :

n ‘ B ico vex , b iconcave , plano convex , plano con

cave , periscopic and toric .

L enses have two kinds of power , minus and plus— the former being thinner in the center

and the latter thinner at the edge . These lenses

c an be made up as a s phere or cylinder . A sphere is a lens with the same power in

all its meridians .

Cut s how in g h ow th e me r id ia n s o f a n e y e a re n umb e red

f rom rig h t t o l e f t . O PHTHALM I C DI C TIO NARY 2 5 7

A m eridian is any straight line drawn from

edge to edge over its optical center . The optical center being a point in line with

th e thickest part of a plu s and the thinnest

part of a minus lens . A cylinder is a lens with power in all merid

ians but one , this one , having no power and is

called its axis . The full power of a cylinder is

always found at right angles to its axis . In the following diagram we will use a plus four dioptry sphere and plus four cylinder for example :

Notice that the power is the sam e in all

meridians of a sphere , while those of a cylinder vary in power . An optical prescription is nothing more than

an order for a lens of a given power and shape .

and when it i s transposed , the shape is changed but not its optical value ( or power ) ; for in

stance , we take the following prescription

4 . 4 e h . . 1 80 p 3 cyl ax . which reads plus four sphere combined with a 1 80 plus four cylinder , axis . The optician , on

receiving this prescription , will grind the plus four sphere on one side of the lens and a plus

four cylinder on the other and cut it out . so 2 5 8 PO C KE T

that the axis of the cylinder will be at 1 80° This lens being plus on both sides is known a s

a biconvex lens .

In this example we have the sphere and cylin r de separated and together , showing their com bin ed powers and also their appearance from

the side . It should be noted that the sphere does not change its value under the axis of the

cylinder , thus forming one of its principal

m eridians . In order to change the shape of this lens we must apply the following rule : When the signs of the sphere and cylinder

are alike , that is , both plus or both minus , add the values together for your new sphere which

n n would be plus eight , the change the sig of

your cylinder , which makes it minus , but do not a 9 0 change its value . Change its axis t king

2 6 0 LE W IS PO C KE T

twenty pairs of convex and the same number of concave cylindrical lenses ranging from

- -D ten D , up to 6 ioptry ; at least prisms from 1 to a plai n red tinted glass ; some shades of smoked glasses ; an opaque disc ; stenopaic slit ; pin hole disc ; a ground glass disc ; a M ad

dox rod , or double prism , and a retinoscope ;

two trial frames , one having three cells to b e

r a T i l C a s e.

I n used fitting , the other two cells , so that w e may allow a patient to wear his correction for

a short time and still have one to use . The

patient is seated 2 0 feet from th e test card ,

which must b e well illuminated , and shades arranged so that the light will throw no direct

’ rays on the patient s face . P lace a small table holding your trial case on the patient ’ s right hand side ; seat yourself at the tabl e with your

back to the reading chart . Now you will find yourself in a very easy position to change the a lenses . The trial frame is placed upon the p

’ tien t s face a n d adjusted s o that he will look O PH THALM IC DI CTIO NARY 2 6 ]

through the center of th e lenses , having the f ram e as near the face as possible . Now you

are in a position to begin testing . F irst place th e opaque disc over the left eye , always making

it a rule to test the right eye first , as you will find all prescription blanks made out in this

way . N ow instruct your patient to read th e smallest line of letters that he can see with the

naked eye . We will say in this case he read th e

line marked 60. As he i s s eated 2 0 feet from

the chart , vision with the naked eye is You must always remember what the vision with the naked eye is , so that you will b e able to judge whether o r not the vision is improved

with the correction . Now take a plus sphere

-D from the trial case , say plus . 5 0 . , place it b e

fore the right eye , asking the patient to again read the smallest type that he can see clearly .

S hould the patient not read as well , the case

may be one of emmetropia , myopia , or astig

ma tis m the ; but , on other hand , if he read s

just the sam e a s before , or a line better , it i s

a case of hyperm etropia , and w e will now pro

ceed to work out a case of each kind .

rm t r H yp e e o p i a . In thi s case w e will say h e

read line numbered 5 0. Then his vision will be Now we place before this right eye a

plus . 50 S phere , and if the patient reads the

sam e or a line better , it is surely a case of

hypermetropia . N ow, as a plus lens will always

relax accommodation , and we do not want any t eye to accommodate for 2 0 feet , or far he r , we will add more plus in the following manner : take a plus 1 sphere and place it in the second

cell of your trial fram e , then withdraw the plus LE W I S P O C KE T

w . 50. In this way the eye will not be left unco

ered ; again a s k the patient to read , and should he read as well as before we will increase th e plus sphere until the smallest line that he reads

becomes blurred , then we will know that he has relaxed all the accommodation he had in use ; that being the object of the foggi ng system . Then draw the patient ’ s attention to astigmatic

A s tig m a tic W h eel.

‘ wheel , asking him , are all the spokes in the wheel equally clear and of the same density ? If there i s ' no astigmatism the patient will see

the wheel uniformly . In that cas e we would t ask him to again look at the reading char , and gradually reduce the strength of the plus

sphere , until we find the strongest that will

allow the best vi sion . This will be his correc

t . n th ion O e other hand , had the patient told t you that the wheel did not look uniform , b u that one or more of the spokes were much

darker , it would indicate astigmatism . and we would ask the patient which spoke appeared the “

most clearly . Now , suppose he says it is the

vertical , or the spoke running from 1 2 to 6 , then as we wish to know if the patient sees the

2 64 LE W I S PO C KE T

. case Cover the left eye w ith the opaque disc , ask him to read the smallest type he can with

the naked eye , record this vision to compare it

with the final correction . Now place a plus . 5 0 i in the trial frame , and if the patient is myO p c “ ” he will say , I cannot see so well , or in other

words , will not be able to read the same line as before . Then draw hi“s attention to the astig matic wheel and say , can you see the spokes ? ” in the wheel , and do they look equally clear If he cannot s ee any of the spokes clearly

enough to count the lines , remove a quarter D .

of the plus sphere . If with this he fails to see

any of the spokes clearly , remove the other

quarter from the trial frame . If none of the

spokes are yet clear , begin with the weakest minus sphere and gradually increase same a

quarter D . at a tim e until one or more spokes

come up clearly . If they all appear clear at the

same time there i s no astigmatism , and we turn to the reading chart and g ive him the weakest minus sphere that will allow him to read the

“ t. bes This would b e his correction . O n the

other hand , if there i s astigmatism , the wheel

will not com e up equally clear , but som e spokes w ill be plainer than others . The main point is not to increas e the minus sphere after one or

more spokes appear clearly ; for instance , w e will say we have on a minus 1 sphere and the patient tell s us that he cannot count any lines

in any of the spokes as yet . We add to this

sphere a minus . 2 5 which will make it minus , “ and if he says Now I can see one spoke ” f 2 clearly , and it runs rom 1 to 6 , this i s the

time to begin with the weakest minus cylinder , O PHTHALM IC DIC TIO NARY 2 6 5

placing the axi s at right angles to the plain

spoke , increasing its strength until you find the weakest that makes the wheel look uniform in

density . In this case we will say that it re

quired a minu s . 75 cylinder , that cylinder com b in ed with the sphere already in the frame will

be the correction , which will read as follows

A 1 h . 80. sp cyl ax .

’ - - l L T ri a ngle (tri ang g ) . ( . tres three angulus

- angle . ) A three sided plane figure .

’ - - - h ri = T i . r x ri chi a s is (trick a sis ) ( G . t h a ir. ) That

condition where the eyelashes , instead of ex

tending forward , are directed more or less back

ward , so as to com e in contact w ith the cornea . Trichiasis causes a continual irritation of the

eyeball , cl ue to the action of the cilia ( eye

lashes ) ; there i s photophobia , lachrymation , and a constant sense of a foreign body in the

eye . The cornea itself suffers considerable

injury .

' - - T ri c hiti s ( trick i tis ) . (Gr . thrix hair itis

inflammation . ) Inflammation of the root of the

eyelashes .

’ - - = k . T ri c hos i s ( tri o si s ) . (Gr . thrix h air ) A dis

ease of the hair . S ee Trichiasis .

’ - - i h r ik . tr c oos T ri ch roic (tri kro ) . ( Gr three col

e ored . ) That which exhibits three differ nt

colors in three di fferent positions .

’ - - - k ri = th ree T ri ch romati c (tri kro mat i ) . ( Gr . t

chroma color . ) That which has three

colors .

- - - L tri = th ree I n a . T ri gem i n us ( tri j em n ) . (

geminus double . ) T . N e rve, also known as the

fifth , or t rif a c i a l , i s the largest cranial nerve . 2 6 6 LE W IS P O C KE T

a n th e It has two roots , motor d sensor ; it i s sensory nerve of the head and face and motor

nerve of the muscles of mastication . It is a

branch of this nerve that form s the ophthalmic .

( S ee Nerve . )

’ m t - - - - - T r n e r o e . Gr igo o y ( trig nom try ) ( . triangle l

m etry . ) That branch of mathematics which treats of the relations of the sides and angle s of triangles with the methods of deducing from certain given parts other required parts and also of the general relations which exist b e tween the trigonometrical functions of arcs or

angles . P lane trigonometry and spherical trigonometry are those branches of trigonometry in ~~w h ich its principles are applied to plane

triangles and spherical . = . th r . Gr. tri ee T ri pl et . ( ) A combination of

three lenses .

r tri l o s G . o . T ri plo p ia . ( p triple ops eye ) A visual defect in which three images are seen

of the one object .

' - - L T rochl ea (troch l e ah ) . ( . pulley . ) A pulley h shaped part , such as that through which t e

superior oblique muscle passes .

’ -l - - to T rochl ea ri s ( troch e a ris ) . That which refers

the superior oblique muscle .

’ t r Gr. T rop om e e . ( trope a turning metron

measure . ) An instrument for measuring the

movements of the eye . = mer to . T umor ( L . tu e swell ) A f swelling . A growth of new tissue , di fering in

structure from the part on which it grows , not

the result of inflammation .

2 6 8 LE WIS PO CKE T

’ U n du at o T h eor . l ry y A theory that light , heat

- and electricity move with a wave like motion .

' x -n — k - - l L n s = n U n i a i a l ( u e a se a ) . ( . u u o e . ) That

which has but one axis .

’

n r. L . U i oc ula ( unus one oculus eye . ) O nly

one eye .

’ - L . . U n it (u nit ) . ( unus one ) Any standard quantity by the representation and subdivision of which any other quantity of the same kind i s

measured .

’ - - - U remi a ( u re me ah ) . (Gr . urine haima

blood . ) B lood poisoning from retained urinary

excretions .

’ m s -ve- - L a z r Uv a ef o r i ( u for mis ) . ( . uv g ap e

forma form . ) The middle coat of the choroid .

uv . U v ea . ( L . a grape ) The choroid , ciliary

body , and iris together .

’ - - Uvea l ( u ve al ) . That which refers to the v a s cu

lar layer of the choroid coat , or the ciliary body

and iris .

- - U v ea l Co a t . The second tunic or coat of the eye

ball .

’ - - - n Uv e iti s ( u ve i tis ) . ( L . uva grape itis i

fl a mmation . ) That condition in which the uvea

i s inflamed . Iritis .

V. Abbreviation for vision .

- V v n i . e i n . ( L . e o I proceed ) The blood vessels

which convey blood toward the heart . They

are found wherever there are arterie s . Veins

have three coats like the arteries , but they are O PHTHALM IC DI C TIO NARY 2 69

not so thick . The veins draining the eyeball correspond in their arrangement to that of the

arteries , the main groups being the retinal .

“

anterior and posterior ciliary veins . The venae

vorticosae , collects the blood from the choroid ,

ciliary body , and the iris and pierces the sclerotic coat near its equator as four large

trunks about equal distance from one another ,

where it is joined by the episcleral veins . The anterior ciliary veins receive the blood from the S ’ ciliary muscle and chlemm s Canal , and after emerging from th e sclerotic coat it receives as tributaries the episcleral and vessels from the

conjunctiva . These veins upon emerging from the eye unite with the other veins from mus

cles and tissue to form two main trunks , the

superior and inferior ophthalmic , which run along the roof and floor of orbit to terminate

in the cavernous sinus . The ophthalmic vei n joins the internal angular vein ( facial ) at the

inner and outer angle of the orbit , thus escaping

from the orbit in either direction . The inferior O phthalmia vein arises in the veins of the eye

lids and lacrimal sac , it also receives the veins from the floor of th e orbit and p a sses out

through the sphenoidal fissure .

z: V o t . L . vel ocitas . el ci y ( , from velox swift )

Quickness of motion . V V ’ en a e o rti c o s a e ( a whirlpool ) . The vein s which principally form the external or venous layer of the choroid coat ( second tunic ) of the

eye ; so Called from their peculiar arrangement ,

four of them passing out about halfway back .

' - - - Ve n t ri cl e ( ven tri kl ) . A small belly like cavity , as the two inferior cavities of the heart and 2 70 L E W IS PO CKE T

various cavities in the brain , of which there are

‘ in five number , namely , the two lateral , th e

third , fourth and fifth . The lateral ventricles

are the cavities of each half of the cerebrum . The third ventricle is b etween th e optic thalami a t the base of the brain . The fourth V . i s the space between “ the cerebellum and the medulla

. F i . in . s oblongata ifth V the septum lucidum .

e rtex L 2 V ( ver ( . vertex top from vertere

' to turn . ) A turning point ; the principal or

highest point ; top ; summit . The point in any to m figure opposite , and farthest fro , the base ; the terminating point of some particular line or lines in a figure or a curve ; vertex of a curve is the point in which the axis of the

curve intersects it . Vertex of an angle is the

point in which the sides of the angle meet . Vertex of a solid or of a surface of revolution is the point in which the axi s pierces the

surface .

V e rti ca l . S ituated at the vertex or highest point . Vertical line is a line perpendicular tothe hori

zon . Vertical plane . A plane passing through

the vertex of a cone , and through its axis . ( S ee

Vertex . )

V F L i rtua l o cus . ( . virtus power th e hearth .

An imaginary or negative focus .

' - - - - ca Vi s i bility ( vis i bil i ty ) . That which has the

p a city of being seen .

V i s io n . ( L . vid ere to see . ) The ability of the organ of sight ( the eye ) to recognize surround

. B a r ing objects . Dou bl e v , see Diplopia . ino c ul

v . , see ing an object w ith both eyes at the sam e

2 72 P O C KE T

- W A L L BY E . This term has several meanings . It generally refers to white opacities of the cor t nea or a pal e blue iris . S ometimes divergen

strabismus .

W a ve T h eo ry . The theory that light travels in

e L . w aves instead of rays . S e ight

W in k . The act of opening and closing the eyelid

suddenly .

k W in e r. S ee E yelash .

W o rs te d T es t . The common test employed for

- color blindness .

’ E M zn - - - X ANT H LA S A ( a thel as mah ) . ( Gr. xan

2 l m l thos yellow e a s a a beaten metal p ate .) That condition in which there is a flat tumor of

a dirty sulphur - yellow color which proj ects a

little above the skin of the lid . It is found

‘ - most frequently on the upper and lower lids a t

the inner angle of the eye .

’ a t n o - -c - an -o - - X n ho cya p i a ( zan tho y pi ah) . (Gr . xan k thos yellow ya n os z blue ops eye . ) That condition in which there is an inability to

perceive red and green colors .

’ - - m . . X a ntho a ( zan tho mah ) . (Gr xanthos yellow )

A yellowi sh new growth on the skin .

xan th s = l X a ntho p h a n e . ( Gr . o y e l ow . ) A condi

tion in which objects appear yellow .

’ - - z r Gr . x er r z . Xe roma ( e o mah ) ( oa d y . ) That condition where the conjunctiva is abnormally

dry . I ’ I l ' ' \ ? D 2 1; U l l l . I L I C TI O N A RY 7

' - - - - t a m ze . r X e roph h l ia ( rof thal mi ah ) ( G . xeros

dry o p h th a lmos eye . ) Conjunctivitis with

atrophy and no liquid discharge .

’ z- - r r. X e ro s i s ( e o sis ) . ( G xeros dry . ) Abnormal

s drynes o f th e eye .

L P . Y E LO W S O T The macula lutea .

- m tz Y oung H el hol Th eo ry of C olo r Blindn es s .

Y E - 2 ( Thomas oung , nglish physicist , 1 773 1 8 9 ; L z H erman udwig H elmholt , German physicist . 1 8 2 1 The theory that color vi s ion de pend s on three sets of retinal fibers which cor

to th e respond colors red , violet and green .

E IS S ' L D Z S G AN S . The sebaceou s or sweat

glands located at the free border of the eyelid s .

'

Z s L a e t . J GOttfried Z G inn i g m n ( ohann inn , erman

anatomi st . 1 72 7 A circular ligamen t a t th e op tic foramen from which arise s the recti muscles of the eye ; the ligament itself i s a t ta ch ed to the bone and allows th e optic nerv e

to pass through its center .

Z . on e . ( L . girdle ) A girdle or b elt .

Zonul a . A very small m embrane surround ing a

body . A small zone .

Zonul e of Z inn . The suspensory ligaments of th e

- I t s t o f eye lens form th e Zone o f Z inn . consi s delica te fibers which take their origin from th e

inner s urface of the ciliary body , beginning a t

the ora serrata . The fibers are in contact with t th e surface of the ciliary body , but leave it a 2 74 L E W I S PO C KE T

of m the apices the ciliary processes , and , b eco

ing free , divide and pass over to the edge of the

lens , thus forming the anterior and posterior

suspensory ligaments . These ligaments are a t ta ch ed to the capsule of the lens with which

they becom e fused . The space , triangular i n

shape , included between the fiber s of the zonul e or suspensory ligaments and the edge of the

lens is called the Canal of P etit .

n Just outside of the optic erve, wh ere it f pierces the eyeball , is found a circle o blood vessels giving a free supply to the op tic sheath

at this point , and sending branches into the

substance of the nerve to supply nutrition . This circle is known as the Circulus of Zinn or some

times called a Zone of Z inn . —— Gr i . Zon ulitis . ( L . zonula I . tis ) Inflammation

of the zonule of Z inn .

L E PO C K E T

Subj ective symptom s are those described

by the patient . W h y does Astigmatism in one eye some times caus e convergent S trabismus ?

. I n order to prevent the eye with the blurred vision interfering with th e vision of the good eye the patient learns to turn

it toward the nose . Why do w e add and subtract from retino scopic findings ?

’ To place the patient s far point at 2 0 feet . Why is the concave retinoscope superior to the plane B ecause a concave retinoscope combined

- with a plus 2 0D . lens can be used as an

ophthalmoscope . What lens can b e combined wi th plus 2

sphere combined with plus 1 cylinder , axi s

90, that will increase the cylinder and de crease the sphere ? Any minus cylinder unde r 2 dioptries w ith

its axis at 1 80.

What i s false myopia , and how is it pro

duced ? A spasm of accommodation in emme tropia

will cause th e eye to appear myopic , and i s brought about by continual s train a t close

work , exophoria or hyperopia . l s an O phthalmic lens used to improve vision ? t No . The lens is o refract th e light only , which sometimes brings the focus nearer

to the retina resulting in better vi sion . t . Could S trabismus exi st and h e eyes be O rthophoric ? O PHTHALM IC DIC TIO NARY 277

v A . Yes . The de iation may be due to H yper metrop ia or abnormal vision in on e eye

only .

1 8 . Q . Can an eye be parallel with its fellow while we a ring a single prism ? M A . N ot unless the acul a Lutea i s displaced .

e 1 9 . Q . Do prisms make ey s parallel in H etero phoria ?

A . No . They allow th em to deviate from

parallelism . N 2 0. Q . ame three things that would interfere

with the action of accommodation . P A . aralysis , hardening of the l ens , loss of

Crystalline Lens .

2 1 . . Q What three things determine the focal length of a lens ?

A . Curvature , density and distance of object . ? 2 2 . Q . What i s a prism diopter

A . The power of a prism to deviate a ray of

light one centimeter in a meter . ? 2 3 . Q . What are the constituents of Crown Glass

A . Crown glass i s so calle d from the trade

mark by the early manufacturers . I t i s

composed of lime , sand and soda . F G ? 2 4 . . Q What is the composition of lint lass h A . S omew at like Crown only less sand an d

lead i s used to increase its density . ? 2 . 5 . Q Which is the harder, flint or crown glass 2 0 A . Crown glass is about per cent harder,

because it has no lead and more sand . 2 t 6 . . Q Which has the most dispersive power , flin or crown ?

A F lint has the most dispersive power , b e

cause of its h igher index of refraction . 278 LE W IS PO CKE T

Rx 2 7. Q . Transpose the following — 2 1 . cyl . ax . 0 — h 2 2 . . 5 0 . . 1 . s p + cyl ax 80 h 1 . 5 0 s p . + cyl . ax . 60 1 1 1 0 h . . 1 s . A . p cyl ax 5 0 h + sp cyl . ax . 90 l x 5 s ph . 1 cy . a . 1 0

. Wh 2 8 . Q at errors of refraction will the above prescriptions correct ?

. M A. (a ) S imple myopic astigmatism ( b ) ixed 0 astigmatism . ( ) Compound hypermetropic . e l 2 . e a 9 . Q What vision doe s an emmetropic y ways hav e ? E A . mmetropia has no reference whatever to

v t ision , but we expec normal .

3 0. Q. Doe s a hypermetropic eye ever have nor mal vision ? P A . Yes . rovided he i s able to overcome his

error by accommodating .

w n ot 3 1 . Q . Name four reasons why vi sion oul d be normal ?

ff . A . Cataract . F ocus o the retina Amblyopia .

Lucoma . 0 3 2 . 8 3 . Q If an object i s inche s from a + sphere where will the i mage be ? 1 A . 6 inches . I i 2 0 t . f 3 3 . Q an eye look ng fee away sees as well 2 s h ? without as with a + p . should it be worn

Give reason for you r answer .

Y t a ccommo A . es . I t shows relaxa ion from

dation .

3 4 . . Q In correcting astigmati sm where would you

place th e axis of the cylinder , if the spoke

' from 1 1 to 5 was seen the blackest ? 1 0 A . 5 degrees .

LE W I S PO C KE T

t th e of see the re d ligh to right streak , and it woul d require pri sms base in to bring

them together , proving exophoria .

P oints on e s h ould be f a mili a r w it h bef o re a tte mpt ing a S tate E xamination : 1 . Mechanical parts of frames and guards for mounting lenses ; making face measurements for same ; truin g up bent frame s and guards ;

adjusting same to different persons . 2 h . The common s apes and forms an d di 0p tric values of lense s of different kinds ; sub mitting ten different kinds to applicants for

determination of these qualities . P f 3 . ractical fitting with trial case , a test o ! the applicant ’ s practical ability to go through these tests and accurately fit different classes

of cases with lenses .

4 t in . S hadow tes ing , with or without stand strument ; the actual doing of this work and determining the error of refraction by the

meth od . The mirror or instrument preferred

may be used .

5 . Muscle testing , and the use of muscle test

’ ing devices ; a test of the applicant s abil ity to make these tests and draw correct conclusions

from the m and their showings .

in s ru 6 . The proper use of different optical t ments used to measure the refraction of the

eyes or any surface , or the power of the mus

cle s of the eyes . t 7 . Questions on the ana omy and physiology

of the eyes , including muscles , nerves , tissues h and t eir functions . . tran s o 8 . Questions on refraction of lenses , p

sitiou , conjugate foci , i mage forming , and the O PHTHALM IC D I C TI O NARY 2 81

G RO U P O N E . h t 1 . Name t e extrinsic and in rinsic muscle s of the eye .

2 . Describe the Iris , the muscles that control its movements and the mechani sm that causes the pupil to contract and expand , what causes the movements and h ow they assist in procuring clear

vision .

3 . Describe the humors of the eye and why it is — desirable that a certain hum or be more fluid than

the others . f 4 . Describe th e Choroid and its unctions .

i 5 . Describe the Crystall ne Lens . What holds it in position ? What controls and alters its shape ? What is its index of refraction ? What is its strength in diopters and how does it assist in procuring good vision ?

6 . Describe t he O ptic N erve and Retina and their functions . ? 7 . Is th e human eye chromatic or achromatic H ow can it be proven ? h 8 . Describe t e Conjunctiva and its office .

9 . Wh ich part of the eye has the greates t re fracting power ? Why ? 1 0 . Describe the eyelids , eyebrows , eyelashes

’ and the odice of each .

1 1 ; L a ch r mal Glan d a Describe the y , and its p pendage s and their office .

~ 1 2 . In which part of the brain are the optic cen ters situated ? 1 3 . Describe the principal veins and a rteries of the eye .

1 4 . F rom what source does the Cornea receive its supply of nourishment ? ? ? 1 . 5 . What i s meant by abduction Adduction 2 8 2 LE W I S PO C KE T

S ursumduction ? Torsion ? Name the muscles that

produce them .

1 6 . D efine visual angle ; minimum visual angle ;

vi sual acuity .

? ? N s a 1 7. What is P terygium Trachoma y t g mus ? Keratitis ?

1 E lmh l T s h ern in 8 . xplain the H e o ts and c g the i or es of accommodation . Which , in your opinion , i s more reasonable ? Why ?

1 - 9 . What do you understand by Co ordinate movements of the eye ?

2 0. Make a diagram of an eye , showing the

principal parts , briefly describing the functions of

ea ch part .

G RO U P T W O .

1 . E xplain what is meant by the Conjuga t e

movements of the eyes .

2 . What is the refractive condition and ampli tude of accommodation of a person whose P . R .

with a plus 5 D . S phere is 5 0 C . M . and whose 2 1 ? P P i 0 M . . S . . w th a plus D . phzere is C 3 . What is the usual si e of the ocular pupil in uncorrected ametrop es who do not complain of asthenopia? 4 . A person has a fixed deviation outward of one eye of 4 meter angles . What prism will cause h ? t e images to fuse at 5 0 C . M . Where would you place the base of the prism ? u 5 . Describe fully yo r method of measuring the relative strength of the extrinsic muscles of the eyes .

6 . Give the rule for th e pri sm diop ral decentra tion of lenses , and work the following problem by it : A pair of plus 3 D . S . are decentered 5 mm . ? inward . H ow much pri sm value results

2 8 4 LE W IS PO C KE T

t S phere before the observed eye . What two poin s are conjugate and what is correction for that eye ? 2 6 1 7 . In static S kiametry with plane mirror at i inches and a plus D . S . n rear cell of trial frame no movement is found in the zhorizonta l meridian and a plu s . 75 S p h . neutrali es motion in the vertical meridian . What direction had the l ? W shadow before the p us . 75 D . S . was used hat kind and amount of ametropia was indicated ? 1 1 8 . A boy of 1 4 years has vision equal to 2 0 5

without glasses . Would you accept that as proof ? of emmetropia Give your reasons . 1 f 9 . If double concave lens could b e made o air with its radius of curvature 2 0 inches for each _ side , what would be the nature of its refraction if it were immersed in water a nd W hat would be its action on parallel rays of light ? 2 1 0. If a person 5 years of age should come to

you to have a complete examination of the eyes , how would you proceed ? What questions would you ask and how would you procee d to make the examination , together with th e record you would make ? Give full particulars just as if you h ad such a c ase .

G RO UP T H R E E . ? 1 . What i s light H ow does it travel from a luminous point ? What three things may happen to it when it comes in contact with another medium ? 2 ? . What i s reflection Give the law governing i ncident and reflected rays . If a ray i s incident 3 at an angle of 0 degrees , at what angle will it be reflected ? 3 . The radius of curvature of a concave mirror 1 6 ? i s inches . What will be its principal focus O PHTHALM I C DI C TI O NARY 2 8 5

1 2 t o f it a t l f a candle is placed inches in fron , w hat di stance will its image be formed ? ? M 4 . What i s refraction ake a diagram show ing the path of a ray of light as it strikes th e s urface of a plate of glass , as it passes through , and after it emerges . What are the three parts of the ray called ?

t h w 5 . What i s meant by e term surface po er ” of a lens ? A certain lens has a surface power of

plus D . S . on one side and on the other minu s t D . S . What curvatures must a cemen seg ment have to make the reading portion plus 6 D . when the ind ex of refraction i s the same in both parts of the lens ?

6 . Make diagram showing three double convex lenses a n d th e course of parallel rays of ligh t t hrough them , the principal focus , the secondary

focus , and one pair of conjugate foci . 7 D . A plus . S . i s held 3 0 inches from a ? candle . Where will the image be formed

8 . The light from a candle passes through a 3 D S . 5 0 M plus . at C . . Where should a s creen be placed to get the best defined image ? Show

your method of working this problem .

9 . A certain lens focuses parallel rays o f light

2 0 . at C . M What len s must be placed in fron t of it to send th e focus back to one meter ? “ ” 1 0 t ? . Wha is meant by the power of a prism I f you had two weak prism s and desired to know

their powers within one per cent , what method would you employ and how would you proceed to carry out the measurem ent ? 1 1 h w . Describe o bi focal lenses should be a d justed and the position wh ich the reading portion

should occupy . 2 8 4 LE W I S PO C K E T

S phere before the observed eye . What two points are conjugate and what is correction for that eye ? 2 6 1 7 . In static S kiametry with plane mirror at

inches and a plus D . S . in rear cell of trial frame no movement is found in the horizontal

- meridian and a plus . 75 S p h . neutralizes motion

in the vertical meridian . What direction had the l ? shadow before the p us . 75 D . S . was used W hat kind and amount of ametropia was indicated ?

- 1 1 8 . A boy of 1 4 years has vi sion equal to 2 0 5

without glasses . Would you accept that as proof f ? o emmetropia Give your reasons .

1 9 . If double concave lens could be made of air with its radius of curvature 2 0 inches for each

side , what would be the nature of its refraction if it were immersed in water a nd what would be its action on parallel rays of light ?

2 0. If a person 1 5 years of age should come to

you to have a complete examination of the eyes , how would you proceed ? What questions would you ask and how would you proceed to make the examination , together with the record you would make ? Give full particulars just as if you “ had

such a c ase .

G RO UP T H RE E . ? 1 . What i s light H ow does it travel from a luminous point ? What three things may happen to it when it comes in contact with another medium ? 2 ? . What i s reflection Give the law governing i ncident and reflected rays . If a ray i s incident 3 at an angle of 0 degrees , at what angle will it be reflected ?

3 . The radius of curvature of a concave mirror 1 6 ? i s inches . What will be its principal focus

2 86 LE W I S PO C K E T

2 1 . A plus D . plano Cyl is placed in contact D w ith a similar one of plus . 75 axis righ t angles . What i s the resultant combination ?

1 3 . If you desired to find the power of a double concave lens and had no lens measure or neutral

izing lenses , how would you proceed if the index o f refraction of the glass was 1 4 . Give the rule for transposing plus spheres c ombined with minus Cyls and work the following P by it : lus 3 D . S . combined with minus D 2 . C . axi s 4 5 . P lus D . S . combined with minus

D . C . axis 65 .

1 5 . Transpose the following P D lus . S . plus D . C . axis P 2 lus D . S . plus D . C . axis 65 . 2 D M inus 3 D . C . minus . C . axis 75 . 0

M inus 2 D . S . minus D . C . axis 1 5 5 . 1 P lus D . C . axis 9 0 plus 5 0 D . C . axis 1 8 0. 1 D Minus D . S . plus 75 . C . axis 1 3 5 . 1 6 . What error will the following prescription

: 1 D 1 c orrect R . plus . S . minus . 75 D . C . axis 80, 2 combined with degree prism base up . 1 D 7 . escribe Glaucoma . Trachoma . P terygium .

Cataract . Granulated lids . 1 ? 8 . Wh at i s O phthalmia Neonatorum What s imple method will prevent it ? D 1 9 . escribe the fogging method of measuring r efraction and your everyday manner of apply

in g it . 2 ' f 0. A young person complains o Asthenopia and the third trial case shows Myopia of D .

The R etinoscope shows of H yperopia . What would you give in the way of lenses ? W hy would you give them ?