Ophthalmic Surgery Lab

Anatomy of the Eye

Conjunctiva – coverlet like thin transparent membrane that lies over the cornea extending onto the inner lids both upper and lower

Three Layers called “Tunics”

1. Fibrous tunic

Cornea = anterior 1/3rd of eye

Sclera = posterior 2/3rd of eye

On the outer surface of the sclera are the 6 extrinsic (outside) muscles also called EOM (extra- ocular muscles) which are what control globe/eye movement:

Superior oblique (SO), inferior oblique (IO), lateral rectus (LR), medial rectus (MR), inferior rectus (IR), superior rectus (SR)

EOM are controlled by three of the twelve total cranial nerves:

LR6 (SO4) 3

The lateral rectus (LR) is controlled by the VI cranial nerve called the abduscens

The superior oblique (SO) is controlled by the IV cranial nerve called the trochlear

All other EOM are controlled by the third cranial nerve called the occulomotor

Cranial Nerve Review from class:

I. Olfactory –smell (think of the old paper factory in Canton that stinks!)

II. Optic – vision

III. Occulomotor

IV. Trochlear

V. Abduscens

2. Vascular Tunic

Contains two intrinsic (inside) muscles:

Iris – because it is a circular muscle composed of smooth muscle, it can be controlled by medications that allow it to dilate the pupil or contract the pupil Ophthalmic Surgery Lab

Ciliary muscle – controlled the shape of the lens which is what allows you to achieve the function of “accommodation” which is simply put to “focus”

3. Nervous tunic

Retina

Two Cavities in Eye

1. Anterior Cavity

Contains aqueous humor – body continues to reproduce and normally your body maintains this through drainage into the Canal of Schlemm (where cornea meets sclera inside the fibrous tunic) so that you do not overproduce it which can lead to increased intra-ocular pressure)

Contains two chambers:

Anterior chamber = front of cornea to iris

Posterior chamber= iris to lens

Cavities separated by normally intact lining/capsule behind/surrounding the lens

2. Posterior Cavity also called Vitreous chamber

Contains retina and vitreous humor (vitreous body)

Vitreous humor –what you have at birth is all you will ever have

Provides shape to the globe and keeps retina in place

Ophthalmic Medication Classifications

Majority are in a liquid/eye drop (gtt) form. Some are in ointment (ung) form. Ophthalmic Surgery Lab

1. Topical antibiotics

2. Dyes

3. Topical anesthetics

4. Anti-inflammatories

5. Mydriatics – dilate iris hence the pupil to allow visibility into the eye

6. Miotics – constrict the iris making pupil smaller used to maintain a new lens in place post- phacoemulsification or extracapsular lens extraction

7. Viscoelastic agents

8. Irrigants

Examples of frequently used ophthalmic medications:

1. Topical antibiotics - neosporin, erythromycin, gentamycin, neomycin, tobramycin

Often combined with anti-inflammatories

2. Dyes – rose Bengal, fluorescein

3. Topical anesthetics –cocaine, lidocaine, tetracaine, bupivacaine, proparacaine

4. Anti-inflammatories – dexamethasone, prednisolone (Pred-forte)

Often combined with antibiotics

5. Mydriatics – atropine sulfate

6. Miotics – Pilocarpine

7. Viscoelastic agents –Healon, Amvisc

8. Irrigant – BSS (balanced salt solution)

Common Eye Pathologies

Chalazion – benign tumor that is the result of an inflamed swollen oil gland on the eye lid

Corrective surgery called chalazion excision

Pterygium – overgrowth of conjunctiva from inner canthus of eye that can extend into the iris Ophthalmic Surgery Lab

Corrective surgery called pterygium excision

Cataracts – opacity or clouding of the lens

Corrective surgery called phacoemulcification (soft lens seen in younger patients) or extracapsular lens excision (hard lens seen in older patients)

Strabismus – misalignment of the eye(s) due to EOM tone issues

Corrective surgery called Recession Resection (R & R). Patient may only need one or the other or both.

Surgical Considerations:

Careful steady movements when working around MD and microscope; don’t bump either!

Use BSS to keep cornea moist intra-operatively (slow drops periodically out of MD line of sight)

Lint-free towels or drapes

No sponges!

Use Weck Cells (spears)

Preservative-free ophthalmic medications

Never use water in the eye

Powder-free gloves

Careful slow transport if moving to a stretcher or bed post-operatively

Patients are awake so watch your conversations in that they are not inappropriate or loud