Ictllon 2- Conjunctival Surgery
pter 144
anagement of Pterygium Michael R. Grimmett
term pterygium is deri ved from the Greek prerygion In advanced cases, the pterygium encro aches onlo the "'''''''g ~wi ng ." Clinically, a pterygium appears as a fleshy, cornea and may cause visual loss secondary to (l) loss of mass that occurs in the interpalpebral fi ssure . The corneal transparency within the visual axis or (2) irregular pterygium is triangular and is made up of a cap, corneal astigmatism (localiz.ed flattening). Regarding the , and body. The cap, or gray zone, is an arcuate, gray latter phenomenon, a recent study disclosed that the subepithelial, corneal opacity that is at the leading induced irregular corneal astigmatism results largely from of the pterygium (Fig. 144 .1). With chronicity, pooling of tears in advance of the pterygium apex.s In ~;~~;:~~tear pooling in advance of the cap leads to the select cases, however, mechanlcal forces may predominate, ~ of a comeal epithelial iron line (Stocker's line),l leading to tractional corneal flattening.6 Additional evidence head of the pterygium is an elevated white mass that suggests that both spatial contrast sensitivity and glare dis a firm adhesion to the globe. The body of the ptery ability are worsened in patients with pterygie even when a fleshy fibrovascular mass that Is demarcated from the Snellen visual acuity is minimally affected. 1 conjunctiva superiorly and inferiorly by sharp Symptomatically, patients may experience foreign body Vital staining reveals selecHve rose bengal uptake on sensation, burning, teartng, and blurred visIon. Most of surface of pterygia in apprOximately half the cases. 2 these symptoms are related to active Inflammation of the Uth"!:h simultaneous nasal and temporal pterygia can pterygium. In some patients with advanced pterygia, ocular pterygia are more frequently located nasally rather m otility ma y be restricted, leading to diplopia in certain t~m po rall y. l Isolated temporal pterygia are considered fields of gaze. Detrimental cosmetic effects caused by large uncommon occurrence .~ Bilateral ocular involvement pterygia are common. in approx.imately o ne· third of patie nts with p:r.~~a;'·: Active pterygia are characterized by marked " engorgement and progressive g rowth. Some Prevalence will become quiescent with resolution of lhe Epidemio logic surveys indicate that the prevalence rates o f injection and fl attening of the pterygiu.m mass. pterygia vary, depending 00 the exact population under uJtimate reasons for variable growth characteristics of scrutiny. Overall, prevalence (ates range from 0.7% to 31 % are largely unknown. in various populations around the world.l.4. 8-11 Prevalen~ rates fDr pterygia in the United States are reported to range from 2% in the northern states to 7% in the southern states.s As a general rule, prevalence rates for pterygia increase with age, although a decline In prevalence rates has been reported for patients over 60 to 70 years of age.1.8 Reasons cited for this decline Include a lack of self reporting by the elderly and the regression of pterygia with senescence.3 Furthermore, certain studies report an equal occurrence of pterygia in males and females,l whJle others report a male predominance.U 11 Ls possible that the reported differences in prevalence rates for men and women reflect different exposure rates to environmental ,isk factors. Additionally, prevalence rates for pterygia have been found to vary according to race. A population study in West Ma laysia fo und that pterygia were more li kely in those of ChInese descent as compared to those o f Ma laysian or fndian descenl.lO Other authors h ave similarly reponed U l racial differences in p revalence rates. 1749 _X:
S~on 2: Conjunctival Surgery
Pathogenesis Hi stOrically, numerous other diverse theories have been Early work by Cameronll indicated that pterygia occur put forward to explain pterygia formation to include local more commonly where ultraviolet light intensity is highest. tear film abnonnalirles,24 chronic ocular irritation,~ chronic Specifically, a high prevalence <;:If pterygia occurs in an inflammation wilh production of a pterygium angiogenes is equatorial belt bounded by latitudes 37° north and 37" facto r,2.'l immunOlogic mechanisms related to type I hyper south. Confuming Cameron'sl l observations, Mackenzie sensitivity/h hereditary factoTS,17 altered elastic tissue et al14 found thai those who live at latitudes less than 30" formation by actinicall y damaged fibroblasts ,:'.11 and human during the first 5 years of life have a 40-fold increased risk papillomavirus. 29 Additionally, nea rl y one-half of ptery· of pterygium development. Overall, it is generally accepted gi um samples show abnormal expression of pS3 tumor that ultraviolet light exposure is linked to the fo rmation suppressor gene, a common marker for neoplasia known to I 1 of pterygia. $-\9 Additional support for this theory is the control cell cycle, cell differentiation, and apoptosis.lO..l observation that pterygia are more common in those who The numerous different pathogenetic theories that have work o utdOOrs, especially if the activity is o n o r near a been proposed point to the fact that the ultimate patho· highly reflective surface.'1,14 genesis of pterygia remains speculative. Another suggested causative fa ctor is the chronic ocular exposure to irritants such as dust. Detels and Dhir ~ reported that the age.adjusted prevalence of pterygia in factory Histopathology sawmill workers (an indOOr occupation) is approximately The histopathologic features of pterygia were thoroughly three times higher than that of a matched control group. outlined by Fuchs in tne 1890s. These include an increased , Subsequentl y, Co roneol5 has qut'Stioned the possible number of thickened elastic fibers, hyaline degenerallon presence of refl ected or scartered ultraviolet light in these of the conjunctival ti ssue, concretions, and epithelial particular work environments. changes. 32 Austin et al2R have similarly summarized the Interestingly, neither exposure to ultraviolet light nor histopathologic findlngs as follows: (1) hyalinization of the exposure to irritants precisely explains the observation subepithelial connective tissue of the substantia proprta , that pterygia arl! predominantly found on the nasal bulbar (2) diffuse or lobular collections of eosinophilic granular conjunctiva. $everaltheorjes have been put forth to explain material with an associated increase in the number of fibro this finding: (1) the temporal surface of the eye is normally blasts and other cell s, (3) an increased number of th.i ckened shaded from light by the longer lashes and curvature of the and tortuous fibers thai stain strongly with elastic stains temporal upper eyelid,13 (2) the nonnal orbicularis contrac· (elaslotic material), and (4) concretions within the hyaliniled tion in bright light provides greater relative coverage of the and granular areas that may show either eosinophilia or temporal bu lbar conjunctiva,20 and (3) light incident from basophilia. a posterolateral aspect to the eye is focused by the temporal In rderence to the characteristic elastotic material within peripheral cornea to the nasal limbus, causing focallimbal pterygia, the tenn "elastotic degeneration" was coined to stem cell dysfun ctionYi Regarding the third theory, it is describe the conditio n of tissue uptake by Weigert's and presumed that the normal anatomic relationships of Ihe Verhoff's elastic tissue stains but the lack of i eyelids and nose would provide relative ocular shielding degradation by pancreatic elaslase. 33 While this specific of incident light from the superior, inferior, and nasal stai ning characteristic is not universa l for pterygia,J3 It 1$ directioos. generally accepted that the elaslic fi be rs within pterygU In support of the notion that abnormallimbal stem cells are abnormal. Historically, Hogan and AJvaradol2 stated that are the primary abnormali ty in the pathogenesis of pterygia the elastotic material within pterygia is fanned hom fout is the localization by immunohistochemical techniques sources: (1) degenerating coUagen, (2) pre-existing elas tic of altered limbal eplthelial stem cells at the leading edge fibers, (3) abnormal fibroblastic activity, and (4) abnormal of pterygia along the normal corneal epithelial basement ground substance. Ultrastructural analysis by Austin el aJ2I membrane.11 It is accepted that a healthy limbal stem cell attributed the elastatic degeneratio n solely to abnOlffi;' populatio n provides a stable junctional barrier that 6broblastic activity with Ihe production of abnormal prevents conjunctivalization of the comea.22 AU ered limbal rational foons of elastic fi bers. Mo reover, collagen de:g""' basal epithelial cells produce elevated leveLs of matrix alion was demonstrated only in the subepithelial metalloproteinases (MMPs), which are collagenolytic and accounted for the light microscopic finding of hy,lil,. enzymes probably responsible for the dissolution of degeneration. 28 Bowman's layer and extracellular matrix.23 Based on these HistopathologiC analysis of the findings, pterygi um fonnatio n may ultimately represent a by CameronH disclosed the following: ( focal 11mbal stem cell dysfunctional state. This tenel is in separating the basal co meal epithelial layer from contradistinctio n to o ther palhogenetic theori es that have layer, (2) altered o rientation of the basa l corneal focused on a primary degenerative response of the con cell s overlying the tibroblasttc tissue, (3) destruction junctiva. SpeCifically, Hill and Maske)6 postulated that Bowman's layer and the superficial com eal stroma actinic damage to the corneal or conjunctivallissue causes lying the fibroblastic tissue, and (4) normal corneal abnormal antigenicity and leads to a chronic inflammatory proximal to the leading edge of Ihe pterygium. As slated 1750 cell infilrrate with a subseq\lent reparative fibrovascular previously, immunohistochemical stai ning has response. strated the presence of altered limbal basal stem I ~:~ the dissolved edge of Bowman's layer and the tibIO Medical approaches 'f': tissue of the pterygiaY Other histologiC changes have been identified in the epithelium of pterygia General recommendations for the prevention of ptery gium formation should lncJude the avoidance of exposure . ~~~~~,:(~;:~~cell metaplasia, acanthosis, dyskeratosiS, lS ,iI goblet cell density,36 and increased mast cells,)7 to ultraviolet radiation. A survey of patients in Australia A recurrent or secondary pterygium is defined as a pterr disclosed that there was a doubling of risk for pterygium recurrence after primary surgiCal excision. A secondary formation associated with never wearing a hat outdoors pteryglum often has a more exuberant fibrovascular growth between the ages of 20 and 29 years.li Additionally, there "'10m,,, than the original pterygium. The histologIC find was a ninefold increased risk of pterygium foonation U of secondary pterygia rnffer from primary pterygia in glasses were never worn in the decade before the ptery the typical degenerative connective tissue changes are gium developed. Since the development of pterygium is . Cameron suggested that the surgical trauma after strongly associated with ultraviolet exposure within the excision leads to an accelerated fibrovascular pro first 5 years of life,14 parents should be advised to protect their chlldren from ultraviolet exposure, especially if the "",t,,, response. 13 latitude of residence is within 300 of the equator and a great deal of time is spent outdoors. Hence, in areas where general, conservative therapy for pterygium is warranted exposure [s high, the use of ultraviolet-absorbing protective unless one of the following circumstances arises: (1) Joss spectacles, sunglasses, and hats is advisable. Lateral ocular of visual acuity either because of induced astigmatism Ot exposure to inCident light can be aVOided with wraparound sunglass designs. :'~~~~.~';~I" onto the vjsual axis, (2) marked cosmetic I!,1 , (3) marked discomfort and irritation unrelieved Mild Irritative symptoms from pterygium may be medical management, (4) limitation of ocular motility managed with topical lubricants or a mild topical anti secondary to restriction, or (5) documented progreSSive histamine/vasoconstricto r (e.g., naphazoline qid). A mild growth toward the visual axis so that it is reasonable to topical corticosteroid (e.g., flu orometholone 0.1% gid) or assume that visual loss wi!! ulttmateLy occur. In such drewn nonsteroidal may be useful for moderate to seve.re vascular stances, surgicaJ intervention is required. Because recur injection and irritative symptomatology. Secondary dellen rencE'S after pterygium excision are frequent and aggreSS ive. may be managed with preservative-free lubricating oint firm indicatiom for surgical removal should exist befOre ments and temporary patching for 24 hOlUS. primary excision. Preoperatively, a carefuJ history and physical examin Surgical approaches ation are mandatory to rule out the diagnOSIS of a pseudo pterygium. A pseudopterygium is an inflammato ry The fact that numerous diHerent techniques ex.ist for the adherence of the conjunctiva to th.e cornea in response to surgical treatment o f pterygium underscores the point that chemical, thermal, or traumatic lnjury and can occur at no single app roach is universa.lly successful.18 While this any point around the limbus. Many corneal inflammato ry statement makes the actual treatment selected appear arbi disorders can also predispose to fibrovascular ingrowth trary, certain treahnent techniq ues offer clear.cut advao· fhal may resemble pterygia. Clues leading to the diagnOSiS tages for success. The interested reader is referred to an of a pseudopterygium include: (1) any anatomic location article by Rosenthal for a review o f the chronology of ptery· other than the interpalpebral fi ssure, (2) dHfuse corneal gium therapy.l9 What follows is a rev1 ew of the su(gical involvement in multiple locations, (3) historical information options currently available for the treatment of pterygia. of a past significant ocular inflammatory event, (4) the lack of anatomic configuration ("body" and "head") typical or pterygium excision or avulsion a pterygium, (5) a pterygium that bridges the limbus SO All procedures. regardless of adjunctive measures employed, that a probe can be passed underneath the body at the begin with the surgical removal o f the pterygium from limbus, or (6) the presence of corneal thinning underlying th e globe. There are numero U.$ techniques that have been the pterygium head. Depending on fhe ultimate etiology published extensively in the Itterature.40 Dissection may be of the pseudopterygium, surgical excision may not be ihdi· carried out from the body to the head of the pterygium or, cated. If the preoperative examination discloses corneal alternatively. from the h ead of the pterygium toward the thinning underlying the pterygium head and surgery is to body. As a general rule, when the pterygium head involves be perfonned, donor corneal tissue should be available the cornea, care should be taken to perform only a super intraoperatively in case a lamellar keratoplasty is required fietal cornea l di ssection, ju st deep enough ·to remove the because of an inadvertent comeal perforation. pterygium. Deep lamellar keratectomies offer no distinct The differential diagnosis of pterygium should also advantages, since the resection may produce postoperative include conjunctival intraeplthelial neoplaSia, squamous ocular surface abnormalltles and alter corneal tensile ceU carcinoma, and a corneal macropannus. The charac strength. To avoid deep lamellar dissections, Rich et al 38 teristic features of these entities should dlstlngulsh these recommend avulsing thin, relaUvely transparent, primary disorders from a pterygium. A limbaJ dermoid is also In the pterygia by mechanically shearing off the pterygium head differential diagnosis but is less likely to be confused with from the underlying cornea with the use of forceps. Advan 1751 a true pterygium. tages cited for this method include a resultant smooth II: THEAAPEUTlC AND RECONSTRUCTIVE PROCEDURfS Sectk>n 2: Conjunctival Surgery
corneal surface, rapid epithelializarion, and minimal scar attentio n not to recess or advance the margins excesSivel y. ring postoperatively. It should be no ted that many pterygia At this point, the surgeon can proceed with conjunctiva! cannot be avu lsed from the cornea in a smooth continuous autografting for either primary o r recu rrent pterygium. plane and must be exdsed. Another method described for After pterygium excision, numerous au thors In the past removi.l1g th e pterygium head that avoids inadvertent deep advocated a "bare sclera" technique In which the resultant disseclion dates back to the seventh cenhlry:,l a suture is scleral and corneal defects would be left to epithelialize passed underneath the body of the pterygium and, with a postoperatively. It was theorized that a pterygium recur sawing motion toward the cornea, the head is dissected rence would be prevented if the corneal epithelium could from the underlying corneal tissue. heal before the conjunctival epithelium reached the A reliable method of excision has been described by Iimbus.~4 Ma n y autho rs claimed impressive success rates Ken yon el .1 142 Ret(Obulbar anesthesia and a lid block are with this bare sclera technique.«--* Unfortunately, controlled used, as the pro longed surgical time required to! conjunc studies were no t perfonned to va lidate these reports. Indeed, tival autograftlng warrants this. HowtV'er, if simple excision using a si milar bare sclera technique, Youngson4-1 reported alone Is to be carried out, adequate a nes the~ia may be a pterygium recurrence rate of 37% and concluded that obtained with topical tf'tracaine and a local subconjunctival "the procedure is unsound" and "pterygi a should not injection of lidocaine. A rigid lid speCUlum aids in maximal be !Tea ted surgically." Krag and £hJers reported a 91 % ocular exposure. Limbal stay sutures 3rt' placed at the recurrence rate (20 of 22 patients) USing a bare sclera ptery· 12 o'clock and 6 o'clock pOSitions to rotate the globe for gium resection technique in combination with exclmer maximal surgical exposure. Forced duction testing is per laser corneal ablation to smooth the corneal surfaceY formed to disclose restricted ocular motility. The head of Variations in follow-up times, dropout rates, and defulitioru the pterygium is dissected from the comea by tenting up of recurrence make direct comparisons between the studies the pterygium apex with fine forceps and then performing difficult. a delineating keratotom y at the leading edge wit h a rounded sharp blade (e.g., No. 69 Beaver blade) to obtain a super Transplantation of the head of the pterygium fi cial plane 01 d issection . Al ternatively. in certain cases a Various techniques o ri ginated in the nineteenth century to peripheral to central dissection is employed if the leading redirect the head 01 the pteryg1um away from the cornea edge is indistbcl. The remainder of the pterygium head is to prevent recurrences. The surgical procedure consisted of carefully dissected hom the superficial cornea in a lamellar burying the pterygium head underneath the norma! fashion up to the limbus with a Tooke knife. The conjunc conjunctival edge inferiorly after surgica l dissection of the tival extent of the pterygium to be excised is then marked head from the comea. Unfortunately, recurrence rates of with a gentian violet marking pen. The pterygiwn body can 30% to 75% were reported with these techoiques. 40AI Such be elevated with a subconjunctival injection of balanced transplantation procedures have been largely abandoned salt solutlon to aid in the dissection and hel p protect the secondary to high recu rrence rates and poor postoperati ve rectus muscle fro m inadvertent damage duling the surgery. cosmetic results. The gentian vio let marks ensure that the extent of excisio n is accurate, since the subconjunctival injection alters tlle Conjunctival flaps and conjunctival autografts preoperative anatomic landmarks. Excision of the bulbar Va ri OuS surgical strategies for the treatment of pterygiwn conjunctival extent of the pterygiu m IS carried Qut up to have developed usI ng the premise that close approxlmatiOfl the 11mbus using blunt dissection with Wescott scissors. of healthy conjunctival tissue at the denuded limbus after The pterygium is then t'.Xcised from the remalning limbal pterygium excision prevents rerurre nC e~. The three basic attachment with scissors. All involved conjunctiva, under variations on this theme include exdsion with primary lying Tenon's capsule, and scar tissue are ultimately removed conjunctival closure, t'.Xcision with conjunctival nap for· down to bare sclera. During the diSSection, care must be mation, and conjunctival autografts. eXercised to avoid damage to the underlying rectus muscle, Primary conjunctival closure after pterygium i . which can become enmeshed in pterygium-associated fibro achieved by undermining adjacen t normal superior vascular tJssue (espedally in recunent cases). The rectus inferi or bulbar con junctiva and pulling the cut conjunc musde can be identified with a muscle hook and a traction tiva l edges together. Such a strategy was employed a~ suture if necessary. Wet field cautery is used to cauterize as 1911 by Terson .40 While controlled stud ies are not bleeding vessels as necessary. Remaining tissue artachments able, recurrence rat es have varied from 2.1% to 88% at the li mbus ace first scraped with a rounded sharp blade this technique.48.49 Patient age less than 40 years and then the cornea, limbus, and adjacent sclera are polished aggreSSive: pterygIum activity have been cited as risk facto rs with a diamond bu rr. H Care is taken not to polish the tissue for recurrences. t8 exceSS Ively \\lith the diamond burr because a surface with Rotational conjunctival flaps to cover the pterygium multiple different levels and irregularities can be created excisional sit e have been employed si nce toe with aggressive polishing. Forced duction testLng is repeated AratoonSO in 1967 reported a recurrence rate of less as appropriate to ensure that normal ocular motility is 1% in a series of ISO consecutive procedures by rt! stored. The exposed buTbar conjuncllval margins are then conjunctival pedicle flap after pterygi um resec1lon. 1752 tacked down to the sc lera w:i~h sevesal 10-0 nylon sutures tunately, Matoon's study did not include a contlOl (o ther authors advocate 8.041 o r 9-0 Vicryl suture) with A repan by Wilson and Rournesl discussed a "eli",",o"" nap technique o riginally descri bed by compared conlunctival autograft to conjunctivaJ- llmbal Known as a con junctival z-plasty, the procedure autograft for advanced primary and recurrent pterygium, rotating a nap of nannal conjunctiva into a limbal and found zero recurrences (28 primary, 15 recurrent) In the wttile simultaneously rotating the remaining Ilmbal group compared to 8.3% (primary 2/24 patients) to O!r)1~"m body laterally onto the bulbar conjunctiva after 33 .3% (recurrent 4/12 patients) in the autograft alone the pterygium head hom the cornea. While no group wtth a minimum follow-up of 3 years. runenc:efigures are quoted, the authors cite two advan· Complications from conjunctival autograftlng are of the procedu re: the preservation of normaJ can· infrequent and not gene.ra1ly sight threatening. Before per """" for possible future autografting and the fcnnatlon forming: an autograft, the interested reader is referred to an barrier of normal conjunctival tissue adjacent to the excell ent review of postoperative problem prevention and to preveor recurrent pterygium growth onto the management for conjunctival autografts that was published McCoOO'lbes et alB reported a recurrence rate of by Starck et al 60 in 1991. Minor problems such as con by using a sliding conjunctival flap after primary junctival graft edema, corneoscleral dellen, and epithelia1 lecy,~;rn exdsion in 258 eyes with an 86% follow-up rale inclusion cysts are encountered infrequently. Less common rniIUnJum of I year. With the same method of surgery, problems include corneal astigmatism, hematomas. Tenon's reported a rerucrence ra te of 1.6% in 913 patients with granuloma, retraction and/or necrosis of the graft. and pterygium after an avefage foUow-up of 5.7 yea rs. extraocular muscular disinsertion. For optimal surgica l low rerurrence rate and the avoidance of potentiaJly results, Starck et a16() emphasize caJeful dissection of Teno n's 1~~~~c~ad~~i~u:nctive measures are encouraging. tissue from the conjunctival graft and recipient bed, minimaJ '( autograft transplantation was described manipulation of tissues, and accurate o ri entation of the a tteatment for pterygium by Kenyon et al-t2 in 1985. graft. Allan et a l ~ concur with the Jaw compllcatlan rate this technique, a free conjunctival graft from the of conjunctival autografting while reporting one Tenon's Upe .otemporaJ bulbar conjunctiva is used to resurface the granuloma, one conjunctival inclusion cyst, and three scleral surface after pterygium resection. A 5.3% wound dehiscences after 93 procedures perfonned. All ';',"""e rat e was reported after 57 procedures (41 recur. complications in Allan's seriess~ were corrected With minor pterygia and 16 primary pterygia) with a mean follow surgical revisi.on without recurrences. Vrabec et al 61 reported of 24 months.~z The authors recommended this two cases of subconjunctival fibrosis at the harvest si te modality for advanced primary and recurrent causing extraocular muscle restriction with concomitant ~:~~~~pfct: ~erygium, especially when concurrent fornix diplopia in one patient. Suggestions for management of ~ is required or when conjunctival scarring this fibrosis induded early frequent tOpical corticosteroids lhe extraocular muscles.. LewallenH reported a and/or pOSSible primary closure of the harvest site conjunc raJl(lonliz,ed trial o f conjunctival autografting versus a bare tiva at the time of the original surgery. technique fo r pterygium in the Caribbean. 'vVhile The specific procedure for conjunctival autografttng has statisticall y Significant, there was a lower recurrence been previously published by Kenyon et al. 42 With ooly a for conjunctivaJ autografting (3 o f 19 cases) as com· few variations from Kenyon's original report,42 what follows to a bare sclera control group (6 of 16 cases). Another will be a deSCription of the general procedural technique ~~~~~~ review of 93 pterygia treated by conjunctival for conjunctival autografting (fig. 1'J4..2), After the exdsion by AJlan et a1 ~ in Australia re ported a 6.5% of the pterygium as described previously in this Chapter, ~ rate w1th a minimuro of 6 months' follow-up. A the size of the scleral defec t created is measured with : ~~~i~~:,~ s urvey of 71 patients with primary pterygium Castroviejo calipers. The globe is then rotated downward 'b et al s; showed a I-year recurrence rate of 16% USing the stay sutures to expose the superio r bulbar con treated with conjunctival autograft and 40% when junctiva. The dimensions of the intended conjunctival with simple exCision. Overall, recurrence rates mer graft (adjacent to the limbus) are marked with a gentian 'ror'i"'''ti',vai autograftlng are low. Pooling data from eight violet marking pen based on the previous measurements of conjunctival autografting in the treatment of the reclpient bed. The gentian violet marks not only aid in an overall recurrence rate of 21 in 265 the excision of an appropriately sized donor graft but are (7,'9%)." Of COurse, it must be recognized that su'ch Invaluable in preventing inadvertent upslde.down orien data have limitations, since variations exist among tation of the graft in the recipient bed. Adamis et a l ~1 note sped6c surgical techniques used, the proportion of that free grafts as large as 15 x 15 mm can be prepared and secondary recunent pterygia treated, the postoperative used without difficulty. Balanced salt solution is then medical regimens prescribed, the age and location of the injected subconjunctivally outside of the gentian violet populatio ns studied, the length of the Jollow-up periods, marks to elevate the conjunctiva to aid In the conjunctival and the specific definition of a recurrence U5ed by a given dissection. Blunt Wescott scissors are used to iocise the author.S6 A prospective randomized study in patients with conjunctiva outside the gentian violet marks along the pri mary pterygium comparing conjunctival autograft posterior border of the graft. The con junctiva is then under ve~u s conjunctival rotation autograft showed equal recur mined using blunt dissection with ca re taken to not include rence rates (app roximately 6%) after a mean foHow- up or underlying Tenon's capsule in the linal graft The latera) 11 months,sa The inclusion of limba! tissue in the conJunc edges of the donor graft are incised outside of the gentian 1753 tival autograft may be beneficia1 as a barrier. Ai FayezS9 violet marks as the dissection is carried forward. It is II: THElIAPWT1C AND REcONSTRUCTIVE PROCEDURES Section 2: Conjunctival Surgery
~19. 144.2 Conjunctival (lutogl1lft. A, Conjunctival defect pre:.ent Immediately after excision of pterygium. The central (orne important to nOlE' that the graft is purposely eXCised conjunctiva. At this point the gra ft is repositioned intO the outside of the gentian violet marks SO that these marks can recipient bed, with adjustment of lhe tractio n sutures as be used for later orientation. (In the final graft, the limbus necessary. The graft is oriented with the unmarked limb.ll is the edge without any marks.) The donor conjunctival donor edge adjacent to the limbus in the reCi pient bed and graft should be as thin as possible so that postoperative the gentian v10l et marks on the exposed surface of the healing will occur with less Shrinkage. It is also importanr conjunctiva. Adamis et al41 advocate securing the graft that the lirobal conjunctiva is incised last after the entire with approximately eight 8-0 Vicryl sutures; we routinely graft has been dissected forward to the limbus. This aSSures secure the graft to the recipient conjunctival edge and that the graft will not renact and become difficull to handle. underlying episclera with numerous 10-0 nylon sutures The tissues are not allowed to dry during the procedure (buried knots) along with Viery l sutures to avoid a post· and are moistened with frequent applications of balanced operative graft dehiscence. The majority of these sutures salt solution. Handling of the donor conjunctival ti~ue usually extrude OT dissolve on their own by J month post· 1754 only OCCU rs with nontoothed forceps (e.g., a McGregor operatively, wh.i1e the rest usually epitheJialize and remain -'-- conjunctival forceps) so as to avoid a bunonhole in the buried. Because of the use of pennanent sutures, patient "'_!~~ ~. ,.-.~.i" ... " ",' "~""" '. ~ " . ", ..",-, , "':.~_'\o-,j" _-····h.·rl ':"}"}.,...~ .., .... ~. '. ~-...... '-.r_-.' '., {..•...... ~_":/·i.·' ...... "!>--", .... "'. C~""~" , • . -.""'- .... Management of Pterygium Id'se,om,'o," is usually nOt a problem. The occasional exposed .,"""cao be removed after adequate conjunctival healing the early postoperative period. The donor harvest site is to epitheliaJize on its own, which usually occurs in the several days postoperatively. Kenyon et al u advocate 11ostopera,;vB,eo' id ar,d antibiotic ointments. We typically use a steIold-antibiolic drop six time~ a day during the fi rst 1or 2 weeks and switch to a steroid drop alone after that tim e. Drops are 1itJaied according to the degree of inflam mation and may be continued for 4 to 8 weeks, depending on the clinical circumstance (Fig. 144.3). The primary disadvantage of the conjunctival autograft technique is the prolonged operative lime required when compared to other bare sclera or primary closure tech niques. Additionally, an operating microscope is required for optimum results, which can be a probJem fo r ophthal mologis ts in developing countries.62 However, these dis advantages are oU tw'eighed by the lack of sighHrueatening complications and the relatively low recurren ce rates after ,<",1 june".,'\ au tografts. Am niotic membrane transplantation (AMT) amniotic membrane is a thin, semitransparent, tissue fo rming the innermost Jayer of the fetal . The membrane has a thick and continuous membrane with a full complemen t o f collagen IV and VII, fib ronectin, and lamirun-l and _5. 63 It been recognized that basement membrane facilitates ;~~i:~~, of epithelial cells, reinforces adhesion of basal cells,64 promotes epitheU al dUfereotiation, and , epithelJal apoptosis (programmed ceU death)_6s stroma is composed of loose connective tissue that ,ro,n"ins growth factors that may modulate stromal fibro to decrease subconjunctival fibrosis, and protease j i important for promoting epithelial healing redUCing stromal Inflammation and ulceration.66-6Ii iAn",;,,", membrane is typically placed on the ocular surface basement membrane up and stroma (Week·CeI sponge will stick to stroma side only) down. It can be anchored to adjace nt episclera and conjunctiva with 8-0 or 9-0 Vicryl ,IU'" "S, and 10·0 nylon when used on the comea. There afe a number of studies that show efficacy for AMT primary pterygium excision. Prabhasawat et al69 noted the recurrence rate for primary pterygium follOwing exCision with MIT in a prospecti ve study (mean fo llo w-up 11.0 months) was 10.9%, which was higher than the 2. 6% rate obtained with conjunctival autografting in a retro spective srudy (mean follow·up 23.2 months). Tekin et aJ10 treated 28 patients with ANfT with a recurrence ra te of 10.7% Fig. 144.1 Conjunctival autograft. A, Preoperative appearance of pterygium. B, Slit lamp appearance 2 months afte r pterygium eJ(ci sion a mean follow-up of 14.9 months. Lower recwrence al"l use of AMT combined with conjunctival autograft may be excisional techniques with various adjunctive treatment considered, especially when there is a shortage of healthy modalities. In the circumstance of secondary recurrent tissue to completely cover the defect. Both Kim et al 73 and pterygium, the known aggressive clinical course certainly Shimazaki et aJl4 combined AMT with conjunctival-limbaJ warrants some additional treatment strategy other than a autograft in a total of 13 patients and found no recurrences repeat bare sclera excision. Other than conjunctiva! flal» with mean follow-up of 24.3 and 13.8 months, respectively. or autografts, certain investigators recommend the use of Amniotic membrane may suppress inflammation and the adjunctive chemotherapy or radiotherapy to decrease recur· fannalion of fibrovascular tissue, while the conjunctival renee rates. The folloW"ing adjuw_"tive therapies have been lirnbal autograft replenishes limbal stem cells. Amniotic variably recommended for both advanced primary and membrane can be especially useful under certain circum secondary recurrent pterygium. stances: when there is a double-headed pterygium and not enough conjunctiva to cover the defect; a patient with Chemotherapy recurrent pterygium who bas aJready undergone conjunc Thiotepa tival autografting; and patients with glaucoma with a need The nitrogen mustard analog thiotepa, or triethylene to preserve the superior conjunctiva for possible filtering thiophosphoramide, has been advocated as an adjunctive surgery. measure to reduce the postoperative recurrence of pter ygium since 1962.80 Thiotepa is an alkylating agent that Lamellar keratoplasty and penetrating interferes W"ith normal mitosis and cell division in aU keratoplasty rapidly proliferating tissues. It was postulated that thiotepa If Significant corneal thinning is present as a consequence reduced the recurrence of pterygium by inhibiting vasculaJ of previous pterygium surgery, a lamellar keratoplasty may endotheliaL proliferation at the operative slte.4(J be indicated to restore the normal ocular surface integrity. While certain studies advocate different concentratioru Additionally, various authors have recommended a lamellar of thiotepa for patient use,so a common recommendation keratoplasty as a barrier to pterygium regrowth. 75 Whj!e in the literature is to mix 15 mg of thiotepa in 30 ml of the reported series are small, recurrence rates after lamellar Ringer's solution for a final dilution of 1:2000 strength.!! keratoplasties have been reported betw"een OO.kJ76 and 600.kJ. 44 The patient uses the medication topically every 3 hours The successful use of lyophilized donor tissue has been during the day starting 2 days postoperatively for a total 01 described in the treatment of recurrent pterygia with only 6 to 8 weeks.Bl Gerde reported good results with a final one recurrence in 13 eyes. 77 In severe cases where the visual thiotepa concentration as low as 1 :5000.82 Concerning the axis is affected by thinning and scarring, a penetrating stability of this medication, Liddy and Morgan reported no keratoplasty may be indicated to visually rehabilitate loss of potency when the solution was stored at room the eye.4() temperature or at 3°e over a IS-day period, while Cooper reported that the thiotepa solution at 2 weeks lost 35% of , Mucous membrane grafts and skin grafts its potency at room temperature versus only losing 5% In cases in which sufficient conjunctiva is not available of its potency when refrigerated. so Ehrlich recommended for a pedicle graft, Trivedi et al 78 recommend the use of a replacing the thiotepa solution at biweekly intervals for the , mucous membrane graft from the lower lip after a ptery 6-week treatment duration because of the lack of stability gium excision. Trivedi et al reported no pterygium recur data for the solution at 6 weeks.8! rences in 140 patients after mucous membrane grafting for A review of the literature by OLander et al 80 in 1978 a follow-up period of 6 to 12 months. 78 Whjle these results quoted pterygium recurrence rates betw"een 00/0 and 16% are impressive, the clinical circumstance of generalized after pterygium excision and adjunctive treatment with conjunctival disease preventing rotational flaps or auto thiotepa. It was noted that the recurrence rate rises pre grafting is uncommon. cipitously if thiotepa is used for only 2 to 4 weeks post· Wong79 reported that a split-thickness skin graft operatively.8! One study by Kleis and Picos3 with a minimum decreases the incidence of recurrence in cases of secondary of 1 year follow-up used the fe!low eye as a control in recurrent pterygia and presents an acceptabLe "white" eye 48 patients and demonstrated a 31.3% recurrence rate in postoperatively. Unfortunately, the study was not controlled. the control eyes treated with excision alone versus a 8.3% \\Th.ile the postoperative photographs included in the report recurrence rate when excision was followed by 6 weeks of indeed show a "white" patch in the area of the prev:iously thiotepa therapy. excised pterygium, the cosmetic appearance of skJn graft While no systemiC toxicity of topicaL thiotepa therapy ing does not approach the excellent results achieved by has been reported, complications reported include early conjunctival rotational flaps or autografting. Based on the and late-onset poliosis and periorbital skin depigmentation paucity of reports using skin grafts, the technique has not that can be permanent (especially in darkly pigmented gained widespread acceptance in the treatment of pterygia. patients), prolonged conjunctival injection, irritation, con junctival deposition of black pigment, allergic reactions, s4 Adjunctive therapy and scleral perforation. Sun exposure during therapy was suggested as a contributing factor in skin and lash 1756 In an effort to lower the recurrence rates after primary depigmentation. The periorbital skin depigmentation has pterygium excision alone, investigators have combined been cited as the maior reason why thiotepa has not gained orld"'p',,,,.d acceptance in the postoperative treatment of both types of surgeries, but may be explained by the patient population. Mahar,97 in a study with the same dose of mitomycin and length of follow-up, found a recurrence rate of 9.4% in the ntilomyci n group versus 25.9% in the ~~::~~~;,~ Is an antibiotic that was first isolated hom conjunctival autograft group, although the difference was ~ caespitosus by Kala in 1956.ss Clinical trials not statisticalIy significa nt. Overal l, these studies indicate m.itomycin-C in the United States began in the late that adjunctive topical mitomycin·C is effective in reducing far a variety of saUd rumors to include breast, reCUrrences after pterygium exdsion. Othe.r comparisons , gastric, and bladder cancers.56 Systemic therapy and concu.rrent series suggest that the effectiveness of oith' m;tom)'ct,,·C carries risks of myelotoxicity, hemolytic mitomycin In reducing pterygium recurrences Is better syndrome, pneumonitis, hepatic veno-occlusive than radiatio n therapy and at least as good as conjunctival and rare cardiotoxiclty. The topical use of autografting. of 4% versus 46.7%, respectively, with a mean [ollow·up when compared retrospectively to a group of pattents of approxi mately 22 mOlllhs. Cano-Parra et a1 106 showed treated with conjunctival autograft, 7. 1% and 8.3%, similar results in a study o f primary pterygia with intra· respectively, with a mean fo llow-up of 27 mo nths. lIS Then' operative 0.1 mg/mt mitomyci n for S minutes after a mean were no serious complications; however, long-term studies of 14.1 months' follow·up. Mastropa$qua et a1 106 studied are needed for safety rind additional studies for detez· recurrent pterygia removed with bare sclera technique mination of efficacy in recurrent pterygia. with and without intraoperative 0.2 mg/rnl mitomycin fo r 3 minutes, and found recurrence rates of 12.5% References 144A NecrotlJ:lng sciMtis ..nd secOfldary Pseudomonas 17 years after bela irradiation for ptef)'gium. I. 8aJJillqu~-SOmen E, Chan CC, Green WTI.: COrneal epllh...IJal lJo n depOSItion, Ophthatmoklgy 90:729, 1983. 2. Han5efl A, Nom M: Astigmatism and Ntface phfnomena in pteryglum, ActD OfIhthfllmol 58:174, 1980 . VYhile beta irradiation lowers the recurrence rate of 3. ¥oangson RM : f'lelgylum in b r~ e!, Am J Ophthalma/74:9S4. ,972.. 4. Detel~ R, DhiT SP: ~lerygium: a goographlcallNdy, Arch Ophlhalmol ~~~~;:;, significant long-term complications have been 78:-4!!S, ,967. ,rE , including cataract fo rmation and scleral necrosis S. Oldenburg JB (I aJ : Conju.nctlval pterygIa: tntdlanhm of rornral . 144.4). The ri sk o f scleral complications foUowing beta lopographlc clw18es.. COfl"IM 9 :200, 1990. 6. Gridley }.f], Pe lt m~n EM: A lonn 01 v.nable astigmafum inductd by .od',",on may be lessened bydec reasing the treated sur pseudll p.etyglum. o,,'lIhalmk SUfg 11:794. t 986. '~;~:::~,:as the sclera's relative avascularity is particularly 7. Un S el aI: lht efftc1 of plerygl.a on contrast sensitivity and glut 12i Ophth(1!molofr90:96,1983. Boudreau :\. Symp"m Cj, We{b Z et al: Sup pr e~~ion oilCE and 29. Gallagher )1..0 , GlannOudl.l A, HeHlngton CS et al: Hu man ". apoplOsj, in n,am m ary eplthehal cdh hy extracellula{ matttx, Sc1mu papi1lomavl.ru$ in pterygium, Br I OplllhalmolS'!'(7):7S2- 7M, 200l. 267:891-893,1995. 30. G lOwers L Pe'el J.lamh E et al: ProHferati ve i!.cUvily and pS) 66. I 1761