Ictllon 2- Conjunctival Surgery

pter 144

anagement of Pterygium Michael R Grimmett

term pterygium is derived from the Greek prerygion g ~wi ng Clinically a pterygium appears as a fleshy

mass that occu rs in the interpalpebral fi ssure The pterygium is triangular and is made up of a cap

and body The cap or gray zone is an arcuate grayshysubepithelial corneal opacity tha t is at the leading

of the pterygium (Fig 144 1) With chronicity ~~~~~tear pooling in advance of the cap leads to the ~ of a comeal epithelial iron line (Stockers line)l

head of the pterygium is an elevated white mass that a firm adhesion to the globe The body of the pteryshy

a fleshy fibrovascular mass that Is demarcated from conjunctiva superiorly and inferiorly by sharp

Vital staining reveals selecHve rose bengal uptake on surface of pterygia in apprOximately half the cases 2

Uthh simultaneous nasal and temporal pterygia ca n pterygia are more freque ntly located nasally rather

t~mporall yl Isolated temporal pterygia are considered uncommon occurrence~ Bilate ral ocular involvement

in approximately o nemiddot thi rd of pa tie nt s wit h pr~~amiddot Active pterygia are characterized by marked engorgement and progressive g rowt h Some

will become quiescent with resolution of lhe injection and fl atten ing of the pterygium ma ss

uJtimate reasons for variable growth characteristics of are largely unknown

In advanced cases the pterygium encro aches onlo the cornea and may cause visual loss secondary to (l ) loss of corneal transparency within the visual axis or (2) irregular corneal astigmatism (localized flattening) Regarding the latter phenomenon a recent study disclosed that the induced irregular corneal astigmatism results largely from pooling of tears in advance of the pterygium apexs In select cases however mechanlcal forces may predominate leading to tractional corneal flattening 6 Additional evidence suggests that both spatial contrast sensitivity and glare disshyability are worsened in patients with pterygie even when the Snellen visual acuity is minimally affected 1

Symptomatically patients may experience foreign body sensation burning teartng and blurred visIon Most of these symptoms are related to active Inflammation of the pterygium In some patients with advanced pterygia ocular m otility ma y be restricted leading to diplopia in certain fields of gaze Detrimental cosmetic effects caused by large pterygia are com mon

Prevalence Epidemio logic surveys indicate th at the prevalence rates o f pterygia vary depending 00 the exact population under scrutiny Overall prevalence (ates range from 07 to 31 in various populations around th e world l48-11 Prevalen~ rates fDr pterygia in the Uni ted Stat es are reported to range from 2 in the northern sta tes 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 age18 Reasons cited for this decline Include a lack of selfshyreporting by the elderly and the regression of pterygia with senescence 3 Furthermore certain studies report an equal occurrence of pterygia in males and femalesl whJle others report a male predominanceU 11 Ls possible that the reported differences in prevalence rates for men and women reflect different exposure rates to environmen tal isk fac tors Additionally prevalence rates for pterygia have been found to vary according to race A population study in West Ma laysia fo und tha t pterygia were more li kely in those of ChInese descent as compared to those o f Ma laysian or fndian descenl lO O ther authors h ave similarly reponed racial diffe rences in p revalence rates U l

1749

_X

S~on 2 Conjunctival Surgery

Pathogenesis Early work by Cameron ll indicated that pterygia occur more commonly where ultraviolet light intensity is highest Specifically a high prevalence ltIf pterygia occu rs in an equatorial belt bounded by latitudes 37deg north and 37 south Confuming Cameron sl l observations Mackenzie et al14 found thai those who live at la titudes less than 30 during the first 5 years of life have a 40-fold in creased risk of pterygium development Overall it is generally accepted that ultraviolet light exposure is linked to the fo rmation of pterygia I $- 9 Additional support for this theory is the observation that pterygia are more common in those who work o utdOOrs especially if the activity is o n o r near a highly reflective surface114

Another suggested causative factor is the chron ic ocular exposure to irritants such as dust Detels and Dhir~ reported that the ageadjusted prevalence of pterygia in factory sawmill workers (an indOOr occupation) is approximately three times higher than that of a matched control group Subsequentl y Co roneol5 has qutStioned the possible presence of refl ected or scartered ultraviolet light in these particular work environments

Interestingly neither exposure to ultraviolet light nor exposure to irritants precisely explains the observation that pterygia arl predominantly found on the nasal bulbar conjunctiva $everaltheorjes have been put forth to explain this finding (1) the temporal surface of the eye is normal ly shaded from light by the longer lashes and curvature of the temporal upper eyelid13 (2) the nonnal orbicularis contracmiddot tion in bright light provides greater relative coverage of the temporal bu lbar conjunctiva20 and (3) light incident from a posterolateral aspect to the eye is focused by the temporal peripheral cornea to the nasal limbus causing foca llimbal stem cell dysfun ctionYi Regarding the third theory it is presumed that the normal anat omic relationships of Ihe eyelids and nose would provide relative ocular shielding of incident light from the superior inferior and nasal directioos

In support of the notion that abnormallimbal stem cells are the primary abnormali ty in the pathogenesis o f pterygia is the localization by immunohistochemical techniques of altered limbal eplthelial stem cells at the leading edge of pterygia along the normal corneal epithelial basement membrane11 It is accepted that a healthy limbal stem cell populatio n provides a stable junctional ba rrier that prevents conjunctivalization of the comea22 AUered limbal basal epithelial cells produce elevated leveLs o f matrix metalloprot einases (MMPs) which are collagenolytic enzymes probably responsibl e for the dissolution of Bowmans layer and extracellular matrix23 Based on these findings pterygi um fonnatio n may ultimately represent a focal 11mbal stem cell dysfunctional state This tenel is in contradistinctio n to o ther palhogenetic theories that have focused on a primary degenerative response of the conshyjunctiva SpeCifically Hill and Maske)6 postulated that actinic damage to the corneal or conj unctivalli ssue causes abnormal antigenicity and leads to a chronic inflammatory

1750 cell infilrrate with a subseqlent reparative fibrovascular response

Hi stOrically numerous other diverse theories have been put forward to expl ain pterygia formation to include local tear film abnonnalirles24 chronic ocular irritation~ chronic inflammation wilh production of a pterygium angiogenesis facto r2l immunOlogic mechanisms related to type I hypershysensitivityh heredi tary factoTS17 altered elastic tissue formation by actinically d amaged fibroblasts 11 and human papillomavirus 29 Additionally nea rl y one-half of pterymiddot gi um samples show abnormal expression of pS3 tumor suppressor gene a common marker for neoplasia known to cont rol cell cycle cell differentiation and apoptosislOl1

The numerous different pathogenetic theories that have been proposed point to the fact that the ultimate pathomiddot genesis of pterygia remains speculative

Histopathology The histopathologic features of pterygia were thoroughly outlined by Fuchs in tne 1890s These include an increased number of thickened elastic fibers hyaline degenerallon of the conjunctival ti ssue concretions and epithelial changes 32 Austin et al2R have simil arly summarized the histopathologic findlngs as follows (1) hyalinization of the subepithelial connective tissue of the substantia proprta (2) diffuse or lobu lar collections of eosinophi lic granular material with an associated increase in the number of fibroshyblasts and other cell s (3) an increased number of thickened and tortuous fibers thai stain strongly with elastic stains (elaslotic material) and (4) concretions within the hyaliniled and granular areas that may show either eosinophilia or basophilia

In rderence to the characteristic elastotic material within pterygia the tenn elastotic degeneration was coined to describe the conditio n of tissue uptake by Weigerts and Verhoffs elastic tissue stains but th e lack of i degradation by pancreatic elaslase 33 While this specific stai ning characteristic is not universa l for pterygiaJ3 It 1$ generally accepted that the elaslic fi be rs within pterygU are abnormal Historically Hogan and AJvaradol2 stated that the elastotic material within pterygia is fanned hom fout sources (1) degenerating coUagen (2) pre-existing elastic fibers (3) abnormal fibroblastic activity and (4) abnormal ground substance Ultrastructural analysis by Austin el aJ2I attributed the elastat ic degeneratio n solely to abnOlffi 6broblastic activity with Ihe p roduction of abnorma l rational foons of elastic fi bers Mo reover collagen degshyalion was demonstrated only in the subepithelial and accounted for th e light microscopi c finding of hylil degeneration28

HistopathologiC analysis of the by CameronH disclosed the following ( separating the basa l co meal epithelial layer from layer (2) altered o rien tation of the basa l corneal cell s overlying th e tibroblasttc tissue (3) destructi on Bowmans layer and the superficial com eal stroma lying the fibroblastic tissue and (4) normal corneal proximal to the leading edge of Ihe pterygium As slated previously immuno histochemical stai ning has strated the presence o f altered limbal basal stem

I~~ the dissolved edge of Bowmans layer and the tibIOshyf tissue of the pterygiaY Other histologiC changes

have been identified in the epithelium of pterygia

~~~~~(~~~cell metaplasia acanthosis dyskeratosiSlS iI goblet cell density36 and increased mast cells)7

A recurrent or secondary pterygium is defined as a pterrshyrecurrence after primary surgiCal excision A secondary

pteryglum often has a more exuberant fibrovascular growth 10m than the original pterygium The histologIC findshy

of secondary pterygia rnffer from primary pterygia in the typical degenerative connective tissue changes are

Cameron suggested that the surgical trauma after excision leads to an accelerated fibrovascular proshy

t response 13

general conservative therapy for pterygium is warranted unless one of the following circumstances arises (1) Joss of visual acuity either because of induced astigmatism Ot I~~~~~~I onto the vjsual axis (2) marked cosmetic

1 (3) marked discomfort and irritation unrelieved medical management (4) limitation of ocular motility

secondary to restriction or (5) documented progreSSive growth toward the visual axis so that it is reasonable to assume that visual loss wi ulttmateLy occur In such drewnshystances surgicaJ intervention is required Because recurshyrencES after pterygium excision are frequent and aggreSS ive firm indicatiom for surgical removal should exist befOre primary excision

Preoperatively a carefuJ history and physical examinshyation are mandatory to rule out the diagnOSIS of a pseudoshypterygium A pseudopterygium is an inflammato ry adherence of the conjunctiva to the cornea in response to chemical thermal or traumatic lnjury and can occur at any point around the limbus Many corneal inflammato ry disorders can also predispose to fibrovascular ingrowth fhal may resemble pterygia Clues leading to the diagnOSiS of a pseudopterygium include (1) an y anatomic location other than the interpalpebral fi ssure (2) dHfuse corneal involvement in multiple locations (3) historical information of a past significant ocular inflammatory event (4) the lack of anatomic configuration (body and head) typical or a pterygium (5) a pterygium that bridges the limbus SO that a probe can be passed underneath the body at the limbus or (6) the presence of corneal thinning underlying the pterygium head Depending on fhe ultimate etiology of the pseudopterygium surgical excision may not be ihdi middot cated If the preoperative examination discloses corneal thinning underlying the pterygium head and su rgery is to be perfonned donor corneal tissue should be available intraoperatively in case a lamellar keratoplasty is required because of an inadvertent comeal perforation

The differential diagnosis of pterygium should also include conjunctival intraeplthelial neoplaSia squamous ceU carcinoma and a corneal macropannus The characshyteristic features of these entities should dlstlngulsh these disorders from a pterygium A limbaJ dermoid is also In the differential diagnosis but is less likely to be confused with a true pterygium

Medical approaches General recommendations for the prevention of pteryshygium formation should lncJude the avoidance of exposure to ultraviolet radiation A survey of patients in Australia disclosed that there was a doubling of risk for pterygium formation associated with never wearing a hat outdoors between the ages of 20 and 29 yearsli Additionally there was a ninefold increased risk of pterygium foonation U glasses were never worn in the decade before the pteryshygium developed Since the development of pterygium is strongly associated with ultraviolet exposure within the first 5 years of life14 parents should be advised to protect their chlldren from ultraviolet exposure especially if the latitude of residence is within 300 of the equator and a great deal of time is spent outdoors Hence in areas where exposure [s high the use of ultraviolet-absorbing protective spectacles sunglasses and hats is advisable Lateral ocular exposure to inCident light can be aVOided with wraparound sunglass designs

Mild Irritative symptoms from pterygium may be managed with topical lubricants or a mild topical antishyhistaminevasoconstricto r (eg naphazoline qid) A mild topical corticosteroid (eg fluorometholone 01 gid) or nonsteroidal may be useful for moderate to severe vascular injection and irritative symptomatology Secondary dellen may be managed with preservative-free lubricating ointshyments and temporary patching for 24 hOlUS

Surgical approaches The fact that numerous diHerent techniques exist for the surgical trea tment o f pterygium underscores the point that no single app roach is universally successful18 While this sta tement makes the actual treatment selected appear arbishytrary certain treahnent techniq ues offer clearcut advaomiddot tages for success The inte rested reader is referred to an article by Rosenthal for a review o f the chronology of pterymiddot gium therapyl9 What follows is a rev1ew of the su(gical options currently available for the treatment of pte rygia

pterygium excision or avulsion All procedures regardless of adjunctive measures employed begin with th e surgical removal o f the pterygium from th e globe There are num ero U$ techniques that have been published extensively in the Itterature40 Dissection may be carried out from th e body to the head of the pterygium or alternatively from th e h ead of the pterygium toward the body As a general rule when the pterygium head involves the cornea care should be taken to perform only a supershyfietal corn ea l di ssection just deep enough middotto remove the pterygium Deep lamella r keratectomies offer no distinct advantages since the resection may produce postoperative ocular surface abnormalltles and alter corneal tensile strength To avoid deep lamellar dissections Rich et al38

recommend avulsing thin relaUvely transparent primary pterygia by mechanically shearing off the pterygium head from the underlying cornea with the use of forceps Advanshytages cited for this method include a resultant smooth

1751

II THEAAPEUTlC AND RECONSTRUCTIVE PROCEDURfS

Sectkgtn 2 Conjunctival Surgery

corneal surface rapid epithelializarion and minimal scarshyring postoperatively It should be no ted that many pterygia cannot be avu lsed from the cornea in a smooth continuous plane and must be exdsed Another meth od described for removil1g th e pterygium head that avoids inadvertent deep disseclion dates back to the seventh cenhlryl a suture is passed undern eath the body of the pterygium and with a sawing motion toward the cornea the head is dissected from the underlyi ng corneal tissue

A reliable method of excision has been described by Kenyon el 1 142 Ret(Obulbar anesthesia and a lid block are used as the pro longed surgical time requi red to conjuncshytival autograftlng warrants this HowtVer if simple excision alone Is to be carried out adequate a nesthe~ia may be obtained with topical tftracaine and a local subconjunctival injection of lidocaine A rigid lid speCUlum aids in maximal ocular exposure Limbal stay sutures 3rt placed at the 12 oclock and 6 oclock pOSitions to rotate the globe for maximal surgical exposure Forced duction testing is pershyformed to disclose restricted ocular motility The head of the pterygiu m is dissected from the comea by tenting up the pterygium apex with fine forceps and then performing a delineating keratotom y at the leading edge wit h a rounded sharp blade (eg No 69 Beaver blade) to obtain a supershyfi cial plane 01 d issection Alternatively in certain cases a peripheral to central dissection is employed if the leading edge is indistbcl The remainder of the pterygium head is carefully dissected hom the superficial cornea in a lamellar fashion up to the limbus with a Tooke knife The conjuncshytival extent of the pterygium to be excised is then marked with a gentian violet marking pen The pterygiwn body can be elevated with a subconjunctival injection of balanced salt solutlon to aid in the dissect ion and hel p protect the rectus muscle fro m inadvertent damage duling the surgery The gentian vio let marks ensu re that the extent of excisio n is accurate since the subconjunctival injection alters tlle preoperative anatomic landmarks Excision of th e bu lbar conjunctival extent o f the pterygiu m IS carried Qut up to the 11mbus using blunt dissection with Wescott scissors The pterygium is then tXcised from the remalning limbal attachmen t with scissors All involved conjunctiva undershylying Tenons capsule and scar tissue are ultimately removed down to bare sclera During the diSSection care must be eXercised to avoid damage to the underlying rectus muscle which can become enmeshed in pterygium-associated fibroshyvascular tJssue (espedally in recunent cases) The rectus musde can be identified with a muscle hook and a traction suture if necessary Wet field cautery is used to cauterize bleeding vessels as necessary Remaining tissue artachments at the li mbus ace first scraped with a rounded sharp blade and then the cornea limbus and adjacent sclera are polished with a diamond bu rrH Care is taken not to polish the tissue exceSSIvely lith the diamond burr because a surface with multiple different levels and irregularities can be created with aggressive polishing Forced duction testLng is repeated as appropriate to ensure that norma l ocu lar motility is rtstored The exposed buTbar conjuncllval margins are then

1752 tacked down to the sc lera wi~h sevesal 10-0 nylon sutures (o ther authors advoca te 8041 o r 9-0 Vicryl suture) with

attentio n not to recess or advance the margins excesSively At this point the surgeon can proceed with conjunctiva aut ografting for either primary o r recu rrent pterygium

After pterygium exci sion numerous au thors In the past advocated a bare sclera technique In which the resultant scleral and corneal defects would be left to epithelialize postoperatively It was theorized that a pterygium recurshyrence would be prevented if the corneal epithelium could heal before the conju nctival epithelium reached the Iimbus~4 Ma n y au tho rs claimed impressive success rates with this bare sclera techniquelaquo-- Unfortunately controlled studies were no t perfonned to validate these reports Indeed using a si milar bare sclera technique Youngson4-1 reported a pterygium recurrence rate of 37 and concluded that the procedure is unsound and pterygi a should not be Tea ted surgically Krag and poundhJers reported a 91 recurrence rate (20 of 22 patients) USing a bare sclera pterymiddot gium resection technique in combination with exclmer laser cornea l ablation to smooth the corneal surfaceY Variations in follow-up times dropout rates and defulitioru of recurrence make direct comparisons between the studies difficu lt

Transplantation of the head of the pterygium Various techniques o riginated in the nineteenth century to redirect the head 01 the pteryg1um away from the cornea to prevent recurrences The surgical procedure consisted of burying the pterygium head underneath the norma conjun ctiva l edge inferiorly after surgica l dissection of the head from the comea Unfortunat ely recurrence rates of 30 to 75 were reported with these techoiques 40AI Such transplantation procedu res have been largely abandoned secondary to high recu rrence rates and poor postoperative cosmetic results

Conjunctival flaps and conjunctival autografts Va riOuS su rgical strategies for the t reatment of pterygiwn have developed usIng the premise that close approxlmatiOfl of healthy conjunctival tissue at th e denuded limbus after pterygium excision prevents rerurrenCe~ The three basic variations on this theme include exdsion with primary conjunctival closure tXcision with conjunctival nap formiddot mation and conj unctival autografts

Primary conj unctival closure after pterygium i achieved by u ndermin ing adjacen t normal superior inferior bulbar con junct iva and pulling the cut conjuncshyt iva l edges together Such a strategy was employed a~ as 1911 by Terson 40 While cont rolled stud ies are not able recurrence rat es have varied from 21 to 88 this technique 4849 Patient age less than 40 years aggreSSive pterygIum activity have been cited as risk factors for recurrences t8

Rotational conjunctival flaps to cover the pterygium excisional sit e have been employed si nce toe AratoonSO in 1967 reported a recurrence rate of less 1 in a series o f ISO consecutive procedures by conjunctival pedicle flap after pterygi um resec1lon tunately Matoons study did not include a contlOl A repan by Wilson and Rournesl discussed a elio

nap techn ique o riginall y described by Known as a con junctival z-plasty the procedure

rotating a nap of nannal conjunctiva into a limbal wttile simultaneously rotating the remaining

Or)1~m body laterally onto the bulbar conjunctiva after the pterygium head hom the cornea While no

runencefigures are quoted the authors cite two advanmiddot of the procedu re the preservation of normaJ canmiddot

for possible future autografting and the fcnnatlon barrier of normal conjunctival tissue adjacent to the

to preveor recurrent pterygium growth onto the McCoOOlbes et alB reported a recurrence rate of

by using a sliding conjunctival flap after primary lecy~rn exdsion in 258 eyes with an 86 follow-up rale

rniIUnJum of I year With the same method of surgery reported a rerucrence ra te of 16 in 913 patients with

pterygium after an avefage foUow-up of 57 yea rs low rerurrence rate and the avoidance of potentiaJly

1~~~~c~ad~~i~unctive measu res are encouraging ( autograft transplantation was described a tteatment for pterygium by Kenyon et al-t2 in 1985 this technique a free conjunctival graft from the

UpeotemporaJ bulbar conjunctiva is used to resurface the scleral surface after pterygium resection A 53

e rat e was reported after 57 procedures (41 recu r pterygia and 16 primary pterygia) with a mean followshyof 24 months~z The authors recommended this

modality for advanced primary and recurrent

~~~~~pfct ~erygium especially when concurrent fornix ~ is required or when conjunctival scarring

lhe extraocu lar muscles LewallenH reported a raJl(lonlized trial o f conjunctival autografting versus a ba re

technique fo r pterygium in the Caribbean vVhile statisticall y Significant there was a lower recurrence for conjunctivaJ autografting (3 o f 19 cases) as commiddot

to a bare sclera cont rol group (6 of 16 cases) Another

~~~~~~ review of 93 pterygia treated by conjunctival~ by AJlan et a1~ in Australia reported a 65 rate w1th a minimuro of 6 months follow-up A

~~~i~~~survey of 7 1 patients with primary pterygiumb et al s showed a I-year recurrence rate of 16

treated with conjunctival autograft and 40 when with simp le exCision Overall recurrence rates mer

roritivai autograftlng are low Pooling data from eight conjunctival autografting in the treatment of

an overall recurrence rate of 21 in 265 (79) Of COurse it must be recognized that such

data have lim itations since variations exist among sped6c surgical techniques used the proportion of

secondary recunent pterygia treated the postoperative medical regimens prescribed the age and location of th e populatio ns studied the length of the Jollow-up periods and the specific definition of a recurrence U5ed by a given authorS6 A prospective randomized study in patients with primary pterygium comparing conjunctival autograft ve~us con junctival rotation autograft showed equal recurshyrence rates (app roximately 6) after a mean foHow- up or 11 mont hssa The inclusion of limba tissue in the conJuncshytival autograft may be beneficia1 as a barrier Ai FayezS9

compared conlunctival autograft to conjunctivaJ- llmbal autograft for advanced primary and recurrent pterygium and found zero recurrences (28 primary 15 recurrent) In the Ilmbal group compared to 83 (primary 224 patients) to 333 (recurrent 412 patients) in the autograft alone group wtth a minimum follow-up of 3 years

Complications from conjunctival autograftlng are infrequent and not genera1ly sight threatening Before pershyforming an autograft the interested reader is referred to an excell ent review of postoperative problem prevention and management for conjunctival autografts that was published by Starck et al60 in 1991 Minor problems such as conshyjunctival graft edema corneoscleral dellen and epithelia1 inclusion cysts are encountered infrequently Less common problems include corneal astigmatism hematomas Tenons gran uloma re traction andor necrosis of the graft and extraocular muscular disin sertion For optimal surgica l results Starck e t a16() emphasize caJeful dissection of Teno ns tissue from the conjunctival graft and recipien t bed minimaJ manipulation of tissues and accurate o rientation of the graft Allan et a l~ concur with the Jaw compllcatlan rate of conjunctival autografting while reporting one Tenons granuloma one conjunctival inclusio n cyst and three wound dehiscences after 93 procedures perfonned All complications in Allans seriess~ were corrected With minor surgical revision without recurrences Vrabec et al61 reported two cases of subconjunctival fibrosis at the harvest si te causing extraocular muscle restriction with concomitant diplopia in one patient Suggestions for management of this fibrosis induded early frequent tOpical corticosteroids andor pOSSible primary closure of the harvest site conjuncshytiva at the time of the original surgery

The speci fic procedure for conjunctival autografttng has been previously published by Kenyon et al42 With ooly a few variations from Kenyon s original report42 what follows will be a deSCription of the general procedural technique for conjunctival autografting (fig 1J42) After the exdsion of the pterygium as described previously in this Chapter the size of the scleral defec t created is measured with Castroviejo calipers The globe is then rotated downward USing the stay sutures to expose the superio r bulbar conshyjunctiva The dimensions of the intended conjunctival graft (ad jacent to the limbus) are marked with a gentian violet marking pen based on the previous measu rements of the reclpient bed The gentian violet marks not only aid in the excision of an appropriately sized donor graft but are Invaluable in preventing inadvertent upsldedown orienshytation of the graft in the recipient bed Adamis et a l ~1 note that free gra fts as large as 15 x 15 mm can be prepared and used without difficulty Balanced salt solution is then injected subconjunctivally outside of the gentian violet marks to elevate the conju nctiva to aid In th e conjunctival dissection Blunt Wescott scissors are used to iocise the conjunctiva outside the gentian violet marks along the posterior border of the graft The con junctiva is then undershymined using blunt dissection with ca re taken to not include underlying Tenons capsule in the linal graft The latera) edges of the donor graft are incised outside of the gentian violet marks as the dissection is carried forward It is

1753

II THElIAPWT1C AND REcONSTRUCTIVE PROCEDURES

Section 2 Conjunctival Surgery

~19 1442 Conjunctival (lutogl1lft A Conjunctival defect preent Immediately after excision of pterygium The central (orneltll polygorKIl mate~1

proteltU the lundu5 from Ii9ht OKicity B Harvesting of conjunctlval autogl2lh tissue from the 5uperotemporal quadrn Gentian vio let demarcates Ihe margins of Ihe autograft Balanced salt solution is in)eltled subconjunctivally C Excision of the (onjVoCliva clutogrllft stJru with the posteriQf border 01 the graft followed by each lateral border The limbal border is removed last Note that the incision is made ouuide of Ihe gentian viole mark to retbin the marlu on the grilft These marks assist the surgeon in orientltlting tne graft D Conjunctival autograft is secured over bMe Klera with intlYrupted 10-0 nylon wtures

important to nOlE that the graft is purposely eXCised outside of the gentian violet marks SO that these marks can be used for later orientation (In the fina l graft the limbus is the edge without any marks) The donor conjunctival graft should be as thin as possible so that postoperative healing will occur with less Shrinkage It is also importanr that the lirobal conjunctiva is incised last after the entire graft has been dissected forward to the limbu s This aSSures that the graft will not renact and become difficull to handle The tissues are not allowed to dry during the procedure and are moistened with frequent applications of balanced salt solution Handling of the donor conjunctival ti~ue only OCCU rs with nontoothed forceps (eg a McGregor1754

--- conjunctival forceps) so as to avoid a bunonhole in the

conjunctiva At this point the gra ft is repositioned intO the recipient bed with adju stment of lhe tractio n sutures as necessary The graft is oriented with the unmarked limbll donor edge adjacent to the limbus in the reCipient bed and the gentian v10l et marks on the exposed surface of the conjunctiva Adamis et al41 advoca te secu ring the graft with approximately eight 8-0 Vicryl sutures we routinely secure the graft to the recipient conjunctival edge and underlying episclera with numerous 10-0 nylon sutures (buried knots) along with Viery l sutures to avoid a postmiddot operative graft dehiscence The majority of these sutures usually extrude OT dissolve on th eir own by J month postmiddot operatively whi1e the rest usually epitheJialize and remain buried Because o f the use of penna nent sutures patient

_ ~ - _~~ -~i ~ ~ - ~_o-j -middotmiddotmiddotmiddothmiddotrl~ ~ ~- -r_ bull ~_middotimiddot gt-- C~~ bull --

Idseomo 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

11ostoperavBeo id ard 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 inflamshymation and may be continued for 4 to 8 weeks depending on the clinical circumstance (Fig 1443)

The primary disadvantage of the conjunctival autograft technique is the prolonged operative lime required when compared to other bare sclera or primary closu re techshyniques Additiona lly an operating microscope is required for optimu m resu lts which can be a probJem fo r op hthalshymologis ts in developi ng countries62 However these disshyadvantages are oU tweighed by the lack of sighHrueatening complications and the relatively low recurren ce rates after

lt1 june au tografts

Am niotic membrane transplantation (AMT) amniotic mem brane is a thin semitransparent

tissue fo rming the innermost Jayer of the fe tal 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 _563 It

j

ra tes

more

been recognized that basement membran e facilitates

~~i~~ of epithelial cells reinforces adhesion of basal cells64 promotes epitheU al dUfereotiation and

epithelJal apoptosis (programmed ceU death)_6s stroma is composed of loose connective tissue that

ronins growth factors that may modulate stromal fibroshyto decrease subconjunctival fibrosis and protease

i im portant for promoting epithelial healing redUCing stroma l Inflammation and ulceration66-6Ii

iAn membrane is typically placed on the ocular surface basement membrane up and stroma (WeekmiddotCeI sponge

will stick to stroma side onl y) down It can be anchored to adjacent episclera and conjunctiva with 8-0 or 9-0 Vicryl

IU S and 10middot0 nylon when used on the comea There afe a number of studies th at show efficacy for AMT primary pterygium excision Prabhasawat et a l69 noted

the recurrence rate for primary pte rygium follOwing exCision with MIT in a prospecti ve study (mean fo llo w-up 110 months) was 109 which was higher than the 26 rate obtained with conjunctival au tografting in a retroshyspective srudy (mean followmiddotu p 232 months) Tekin et aJ10 treated 28 patients with ANfT with a recurrence rate of 107

a mean follow-up of 149 mon ths Lower recwrence (3 0) have been reported when more extensive

remova l of fibrovascular tissue Is combined with intrashyoperative and postoperative subconjunctival in jection of

al 72long-acting corocoslerolds7J Ma et retrospelt1lvely rompd AMY to conjunctiva autogran and postoperative 02 mgml mitomycin dro ps and found equamiddotJ recurrence rates 38 54 and 37 respectively

Result s are less promising for recurrent pterygium a aggressive disorder Pabhasawat et al69 looked at

Management of Pterygium

Fig 1441 Conjunctival autograft A Preoperative appearance of pterygium B Slit lamp appearance 2 months afte r pterygium eJ(cision alllt conjunctival lttutograft C Note a wdlmiddothealed conjullC1val autograft

recurrent pterygium tIeated with AMT and found a recurmiddot renee rate of 375 (mean follow-up 11 0 months) compared to 9 1 (mean fo llow-up 232 mo nths) using conunctivaJ autograft An eye with recurren t pterygium that has undergooe multiple surgeries usuaUy lacks a great deal of nonnal nonscarred surrounding tissue and may have fornix sh ortening symhlepharon and motility restriction The

1755

_ ~ - _~~ -~i ~ ~ - ~_o-j -middotmiddotmiddotmiddothmiddotrl~ ~ ~- -r_ bull ~_middotimiddot gt-- C~~ bull --

Idseomo 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

11ostoperavBeo id ard 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 inflamshymation and may be continued for 4 to 8 weeks depending on the clinical circumstance (Fig 1443)

The primary disadvantage of the conjunctival autograft technique is the prolonged operative lime required when compared to other bare sclera or primary closu re techshyniques Additiona lly an operating microscope is required for optimu m resu lts which can be a probJem fo r op hthalshymologis ts in developi ng countries62 However these disshyadvantages are oU tweighed by the lack of sighHrueatening complications and the relatively low recurren ce rates after

lt1 june au tografts

Am niotic membrane transplantation (AMT) amniotic mem brane is a thin semitransparent

tissue fo rming the innermost Jayer of the fe tal 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 _563 It

j

ra tes

more

been recognized that basement membran e facilitates

~~i~~ of epithelial cells reinforces adhesion of basal cells64 promotes epitheU al dUfereotiation and

epithelJal apoptosis (programmed ceU death)_6s stroma is composed of loose connective tissue that

ronins growth factors that may modulate stromal fibroshyto decrease subconjunctival fibrosis and protease

i im portant for promoting epithelial healing redUCing stroma l Inflammation and ulceration66-6Ii

iAn membrane is typically placed on the ocular surface basement membrane up and stroma (WeekmiddotCeI sponge

will stick to stroma side onl y) down It can be anchored to adjacent episclera and conjunctiva with 8-0 or 9-0 Vicryl

IU S and 10middot0 nylon when used on the comea There afe a number of studies th at show efficacy for AMT primary pterygium excision Prabhasawat et a l69 noted

the recurrence rate for primary pte rygium follOwing exCision with MIT in a prospecti ve study (mean fo llo w-up 110 months) was 109 which was higher than the 26 rate obtained with conjunctival au tografting in a retroshyspective srudy (mean followmiddotu p 232 months) Tekin et aJ10 treated 28 patients with ANfT with a recurrence rate of 107

a mean follow-up of 149 mon ths Lower recwrence (3 0) have been reported when more extensive

remova l of fibrovascular tissue Is combined with intrashyoperative and postoperative subconjunctival in jection of

al 72long-acting corocoslerolds7J Ma et retrospelt1lvely rompd AMY to conjunctiva autogran and postoperative 02 mgml mitomycin dro ps and found equamiddotJ recurrence rates 38 54 and 37 respectively

Result s are less promising for recurrent pterygium a aggressive disorder Pabhasawat et al69 looked at

Management of Pterygium

Fig 1441 Conjunctival autograft A Preoperative appearance of pterygium B Slit lamp appearance 2 months afte r pterygium eJ(cision alllt conjunctival lttutograft C Note a wdlmiddothealed conjullC1val autograft

recurrent pterygium tIeated with AMT and found a recurmiddot renee rate of 375 (mean follow-up 11 0 months) compared to 9 1 (mean fo llow-up 232 mo nths) using conunctivaJ autograft An eye with recurren t pterygium that has undergooe multiple surgeries usuaUy lacks a great deal of nonnal nonscarred surrounding tissue and may have fornix sh ortening symhlepharon and motility restriction The

1755

PROCEDURESPAIIf Section 2 Conjunctival Surgery

use of AMT combined with conjunctival autograft may be considered especially when there is a shortage of healthy tissue to completely cover the defect Both Kim et al73 and Shimazaki et aJl4 combined AMT with conjunctival-limbaJ autograft in a total of 13 patients and found no recurrences with mean follow-up of 243 and 138 months respectively Amniotic membrane may suppress inflammation and the fannalion of fibrovascular tissue while the conjunctivalshylirnbal autograft replenishes limbal stem cells Amniotic membrane can be especially useful under certain circumshystances when there is a double-headed pterygium and not enough conjunctiva to cover the defect a patient with recurrent pterygium who bas aJready undergone conjuncshytival autografting and patients with glaucoma with a need to preserve the superior conjunctiva for possible filtering surgery

Lamellar keratoplasty and penetrating keratoplasty If Significant corneal thinning is present as a consequence of previous pterygium surgery a lamellar keratoplasty may be indicated to restore the normal ocular surface integrity Additionally various authors have recommended a lamellar keratoplasty as a barrier to pterygium regrowth 75 Whje the reported series are small recurrence rates after lamellar keratoplasties have been reported between OOkJ76 and 600kJ44

The successful use of lyophilized donor tissue has been described in the treatment of recurrent pterygia with only one recurrence in 13 eyes 77 In severe cases where the visual axis is affected by thinning and scarring a penetrating keratoplasty may be indicated to visually rehabilitate the eye4()

Mucous membrane grafts and skin grafts In cases in which sufficient conjunctiva is not available for a pedicle graft Trivedi et al78 recommend the use of a mucous membrane graft from the lower lip after a pteryshygium excision Trivedi et al reported no pterygium recurshyrences in 140 patients after mucous membrane grafting for a follow-up period of 6 to 12 months 78 Whjle these results are impressive the clinical circumstance of generalized conjunctival disease preventing rotational flaps or autoshygrafting is uncommon

Wong79 reported that a split-thickness skin graft decreases the incidence of recurrence in cases of secondary recurrent pterygia and presents an acceptabLe white eye postoperatively Unfortunately the study was not controlled Thile the postoperative photographs included in the report indeed show a white patch in the area of the previously excised pterygium the cosmetic appearance of skJn graftshying does not approach the excellent results achieved by conjunctival rotational flaps or autografting Based on the paucity of reports using skin grafts the technique has not gained widespread acceptance in the treatment of pterygia

Adjunctive therapy 1756 In an effort to lower the recurrence rates after primary

pterygium excision alone investigators have combined

excisional techniques with various adjunctive treatment modalities In the circumstance of secondary recurrent pterygium the known aggressive clinical course certainly warrants some additional treatment strategy other than a repeat bare sclera excision Other than conjunctiva flalraquo or autografts certain investigators recommend the use of adjunctive chemotherapy or radiotherapy to decrease recurmiddot renee rates The folloWing adjuw_tive therapies have been variably recommended for both advanced primary and secondary recurrent pterygium

Chemotherapy Thiotepa The nitrogen mustard analog thiotepa or triethyleneshythiophosphoramide has been advocated as an adjunctive measure to reduce the postoperative recurrence of ptershyygium since 196280 Thiotepa is an alkylating agent that interferes With normal mitosis and cell division in aU rapidly proliferating tissues It was postulated that thiotepa reduced the recurrence of pterygium by inhibiting vasculaJ endotheliaL proliferation at the operative slte4(J

While certain studies advocate different concentratioru of thiotepa for patient useso a common recommendation in the literature is to mix 15 mg of thiotepa in 30 ml of Ringers solution for a final dilution of 12000 strength The patient uses the medication topically every 3 hours during the day starting 2 days postoperatively for a total 01 6 to 8 weeksBl Gerde reported good results with a final thiotepa concentration as low as 1 500082 Concerning the stability of this medication Liddy and Morgan reported no loss of potency when the solution was stored at room temperature or at 3dege over a IS-day period while Cooper reported that the thiotepa solution at 2 weeks lost 35 of its potency at room temperature versus only losing 5 of its potency when refrigerated so Ehrlich recommended replacing the thiotepa solution at biweekly intervals for the 6-week treatment duration because of the lack of stability data for the solution at 6 weeks8

A review of the literature by OLander et al80 in 1978 quoted pterygium recurrence rates between 000 and 16 after pterygium excision and adjunctive treatment with thiotepa It was noted that the recurrence rate rises preshycipitously if thiotepa is used for only 2 to 4 weeks postmiddot operatively8 One study by Kleis and Picos3 with a minimum of 1 year follow-up used the felow eye as a control in 48 patients and demonstrated a 313 recurrence rate in the control eyes treated with excision alone versus a 83 recurrence rate when excision was followed by 6 weeks of thiotepa therapy

While no systemiC toxicity of topicaL thiotepa therapy has been reported complications reported include earlyshyand late-onset poliosis and periorbital skin depigmentation that can be permanent (especially in darkly pigmented patients) prolonged conjunctival injection irritation conshyjunctival deposition of black pigment allergic reactions and scleral perforations4 Sun exposure during therapy was suggested as a contributing factor in skin and lash depigmentation The periorbital skin depigmentation has been cited as the maior reason why thiotepa has not gained

orldp d acceptance in the postoperative treatment o f

~~~~~~ Is an antibiotic that was first isolated hom ~ caespitosus by Kala in 1956ss Clinical trials mitomycin-C in the United States began in the late

far a variety of saUd rumors to include breast gastric and bladder cancers56 Systemic therapy

oith mtom)ctmiddotC carries risks of myelotoxicity hemolyticshysyndrome pneumonitis hepatic veno-occlusive

and rare cardiotoxiclty The topical use of ~~~~n to prevent pterygium recurrence was first4 by Kunitomo and Mari in the early 1960s in

Since Ihal time numerous investigators have re~~gthat tOpical mltomycin-C is efficacious in de recurrence rates after pterygi um excision

FollOWing reductJve activatio n mitomycin-C interacts DNA to form monofunctional adducts as well as

I cross-links between the two complementa ry of DNA Monofunctional adduct formation occurs

10 20 times morc frequently than cross- linking The fmd molecular target in DNA for covalent attachment

mi1omycin-C Is the N2 position of guanJne86 These of DNA arc responsible for the antibiotic and actiVity of mitomydn-C because molecu lar

ca nnot progress normally With such permanent alterat ions Additio nally th e production of toxic

free radica ls h om mitomycin-C in vivo has been 7~ that cauld cause Significant damage to any II[ with umaturated lipids Overall mltomycinmiddotC

greatest anliproliferative effect on those cells show-the highest rate of mitosis

use of i mitomyCin-C after pterygium surgery in the United States by Singh et al88 In a

prospective (aslion after pterygium exdsion were treated with either 10 mglml rnitomycinmiddotC

drops 04 mgml mitomycinmiddotC eye drops or placebo times a day fo r 2 weeks With an average of 5 months

fltlJJowmiddotugt recu rrences were found to be 89 in the placebo versus 23 1n the m itomycin groups combined 58

receiving the 10 mgml mitom yCi n dosage worse conju nctival irri tation superficial

and excessive lacrimation when compared to the receiving the 04 mgml mitomycin dosage No toxicity was reported for either dosage A subshy

publication by the same authors confinned on1y recurrence in 58 mitomycinmiddot treated patients followed

for 1to 2 years69 Subsequent investigations by other authors have confi nnelt the low recurrence ra tes after treatment with 04 mglml topical mitomycin9) Other authors report good success with shorter (Qurses of 0 2 figml mitomycin drops wit h recunence rat es between 5 to 99 1- Chen

al compared conjunctival autograft to postoperat ive O2-mgml mitomycin drops bid for 5 days after bare sclera ncision for primary pterygium in a predominantly young Hispan iC population and found recurrence rates of 39 and 38 respectively after approximately I year These ra les are significantly higher than those of other studies for

both types of surgeries but may be explained by the pati ent population Mahar97 in a study with the same dose of mitomycin and length of follow-up found a recurrence rate of 94 in the ntilomyci n group versus 259 in the conju nctival autograft group although the difference was not statisticalIy significant Overall these studies indicate that adjunctive topical mitomycinmiddotC is effective in reducing reCUrrences after pterygium exdsion Other comparisons and concurrent series suggest that the effectiveness of mitomycin In reducing pterygium recurrences Is better than radiatio n therapy and at least as good as conjunctival autograftingltnI

Although Singh et al88 89 report no Significant complishy

cations from mitomycin therapy and contend that the use o f mitom ycin is safe insuf6cient long term survelUance exists to make this statement with certainty Indeed reports ha ve been pub llshed to the contrary Yamanouchi et al9 reported o n 15 patients with severe scleral complications fo llowing topical mitomyctn instillation after pterygiwn excision J-Iayasaka et apoo reported four cases o f scleral u lceration 18 to 25 years after the use of 04 mgmt mitomycin d rops fou r times a day for 2 to 3 wetks after simple pterygium exciSion Postoperative mitomyci n as an adjunct to conjunctival au tograftlng for recurrent pterygium has been studied in a small number of paUen ts with 2 of 12 having ea rly wound deh iscence and 2 of 12 experiencing recurrence within 9 monthsIOI Additionally Rubin feld el al102 descrtbed the findings in ten patients who experienced serious vision -threatening compUcations aSSOCiated wi th the use of mitomycin after pterygium surgery These complications included severe secondary glaucoma (four patients) corneal edema (three patients) cornea l perforatio n (one patien t) correcto pia (two patIents) iritis (eight patients) sudden-onset mature ca taract (twO patients) scleral caldfication (one patient) and incapacitating photophobia and pain (eigbt patients) Silt patients required 20 operative procedures as a canmiddot sequence of their complications Five eyes had a final visual acuity of 20200 or worse Si nce three of the six patients with the most severe complications had oonmiddot comitant ch rOnic external dlseases Rubinfeld 101 stated that mitomycin-C after pterygium excision is contrai ndicated in patients with keratitis sicca SjOgrens syndrome neuromiddot Tophic keratitis or severe meibomian gla nd dysfunction blepharitis A review of the Japanese lite ra ture by Rubl nfeld et a1 102 revealed reports of scleral ulceration necrotizing scleritis perforatio n iridocyclitis ca taract infection glaucoma scleral ca lCification and loss of an eye afl er pterygi um exciSion with adjun Ctive mitomycin therapy While the exact incidence of these compllcations Is unknown the contention that mllo myciomiddotC therapy is safe remains to be determined with futu re longmiddotterm trials

lnlTaoperative application o f mitomyci n to the scleral bed has been advocated by many authors slnce its use has become routine in glaucoma filtra tion surgery Frucht-Pery et al l 04 compa red hare sclera excision With and without in traoperative 0 2 mgml mito mycin for S minutes in both primary and recurrent pterygia and found recurrence rates

1757

Section 2 Conjunctival Surgery

of 4 versus 467 respectively with a mean [ollowmiddotup of approxi mately 22 mOlllhs Cano-Parra et a1 106 showed simila r results in a study o f primary pterygia with intramiddot operative 01 mgmt mitom yci n for S minutes after a mean of 141 months followmiddotup Mastropa$qua et a1 106 studi ed recurrent pterygia removed with bare sclera technique with and without intraoperative 02 mgrnl mitomycin fo r 3 minutes and found recurrence rates of 125 ltlnd 356 respectively after a mean of 3S months (ollow-up AU three of these studies reported no serious complications Recu rmiddot rence rates afe similar in studies that compare intraoperative mitomyCin to postoperative drops107-109 Scleral thinning is more likely to occur after bare scl era excision with the u se of postoperati ve mitomycin d ropsl0J 1I0 or high er doses (04 mgml fo r 5 minutes) o f intraoper3rive mitom ycin HI Rubinfeld and Stein HO studied 289 pati ents with both primary (155) and recurrent (134) pterygia treated with intraopera tive 02 mgm l mitomycin for 3 minutes followed by conjunctival closure an d fou nd a recurrence rate of 27 with a mean of 26 months fo llowmiddotup with no serious complications Intraoperative 0 2 mgml milOmyci n for 3 minutes with conjunctival closu re has also compared favorably with conjunctival-limbal autograft in recu rrent pterygia 1I2 Comeoscieral melt has been reported in a patient who underwent intraoperative 0 2 rngml mHoshymycin for 3 minutes wUh a sUding conj unctival fla p In Again longmiddotterm data a re scarce but cautio n should be taken whenever using mitomycin intraoperatively or postmiddot operatively in drop form If mitom ycin is used Vole recommend intraopera tive application with complete covering of the exposed sclera

Unfortunately the optimwn dosage and treatment length of topical mitomycin to maximize both eHectiveness an d safety are not precisel y known Clues to the opt imum dosage of mitomydn-C may be inferred hom a study on the inh ibitory effects of mitomycin-C on human Tenoos capsule fibroblasts in cell cu lture cell colony formation was inhibited at mitomyci n concenlTations of 0 1 mgml cell death ensued at mitomycin-C concentrations orO3 rngml and the LDw for these fib roblasts was 02 mgml s Other investigat ors are currently eva luating th e effects of vari ous mitomycinmiddotC concentratlons and application times on vascular endothelium and limbal stem cells in rabbits to ascerta in a dose-response curve OO Rega rding stability of the topica l solution reconsti tuted mitomycin has a pH of 6 to 8 and is stable for 2 weeks when refrigerated at 2-80 c90

Daunorubl(in Daunorubicin isan anthtacycline antibiotic that is primarily used for the treatment of leukemias It inhibits DNA and RNA syntheSiS by inhibiting topoisomera semiddot ][ enzyme and has recently been used intraoperatively during primary pterygium exCision Oadeya and Kamlesh 1l4 showed intramiddot operative application of 002 daun orubicin fo r 3 minutes to be mort effective than ba re sclera exdsion alo ne wi th Iea mence rates of 67 and 33 respecti Ve ly after a mean follow-up of 15 months In a subsequent stldy the patients treated With daunorublCin also had equal recu rrence rates

when compared retrospectively to a group of pattents treated with conjunctival autograft 71 and 83 respectively with a mean fo llow-up of 27 mo nth s lIS Then were no serious complications however long-term studies are needed for safety rind additional studies for detezmiddot mination of efficacy in recu rrent pterygia

Radiation therapy Until the 1950s radon bulbs radiu m pLaques Grenz rays and X-rays were employed in the treatment of pterygia wth variable success -1011 6 tn 1952 strontiummiddot90 was introduced for the treatment of neoplastic disease and has been used extensive ly for the treatment of pterygia since that time StTo ntiummiddot90 is produced in the fi ssion of uraniummiddot2J5 and has a half-life of 28 years Stro ntiu mmiddot90 decays 10 yttriummiddot90 with a halfmiddotlife of 64 hours whiCh in tum

ldecays to zirconlurn-90 which is stable 7 Beta rays from strontiummiddot90 have an ave rage energy of 021 MeV pes disintegration while beta rays from ytTrium-90 have an average energy o f 089 MeV per disintegration III Beta rays expend their energy maximally within the superficial 2 mm of tissue as the dose drops to 41 at 1 mm 1911il at 2 nun 9 at 3 mm and 1 at 5 mm40 This low penetration profile for strontium-90 is important since cataracts may develop should the dose to the crystalline lens approach 1500 to 2500 rep ( I rep 108 rad) -IO

Recurrence rates afte r pterygium exCision with beta irradiation have vaned widely with a low of 0118 to a high of 80119 reported in th e literature Of the Jarger series reported recurrence rates vary between 17 (825 cases) Ill) 6 (975 cases) I2l and 12 (764 cases) l22 Direct comparison of the various studies is difficult beca use of the variatiOns in the populat io ns studied follow-up intervals dosagt regimens and definition of a recurrence The mechanism of action of beta irradia tio n in reducing recurrences is thought to be through the jnhibition of mitosis in rapidly dividing ce lls such as vasj-u lar endotheJial cells11

Various investigators report diffe rent opinions on the total dosage reqUired the need for fractionation or tht optimal time for delivery o( beta irradiation after pterygium excision A literature review by Paryan i et al l20 disclosed that th e total dose of beta Irradiation has varied from 1800 to 6000 tad given in one to six fractions in dlUerent reports Apparently there is some degree of OexibUity in the total dose and the fractionation of beta irradiation delivered after pterygium eXCision wilh different investigators reporting efficacy with widely varying protocols Most investigatoN however hold that the optlma l dose is between 1000 and 3000 rad given at the time o f su rgery o r withi n a fe w days o f surgery41 Aswad and Baum tl3 reponed that a singlt 2000 rad dose given in the immed late postoperative period had a lower recurrence (a te than a Similar dose given 4 days postoperatively in pa tients with secondary recurrent pterygia No statistically sig nificant difference in the of the bel a irradiation was found in patients wilh p rimary pterygia Fmthermore applying the beta irradiation at tht time o f surgery may also allow better control and I of th e treatment and may save the patient additional time and expense40123

1758

144A NecrotlJlng sciMtis nd secOfldary Pseudomonas 17 years after bela irradiation for ptef)gium

VYhile beta irradiation lowers the recurrence rate of ~~~~ significant long-term complications have been rE including cata ract fo rmation and scleral necrosis

1444) The risk o f scleral complications foUowing beta odon may be lessened by dec reasing the trea ted surshy

~~~as the scleras relative avascularity is particularly Vi I to radiation -induced ischemia 12i MacKenzie

1 reported a 13 rate of scleromalacia with a 45 rate ~eveTe scleral thinning in a large population-based study

10 years folJow-up Additionally endophthalmitis a consequence of the scleral necrosis was seen in two

l Z5

~~~~~~~~rr and Constable reported on 63 eyes wit h after pterygium excision l-Yith beta lrradiation from 3 to 20 years postoperatively Scleral ulcershy

was reported In 51 eyes and n on visually disabling lens opadties were identified in 19 eyes Reduced

seconda) to a radiation-induced cataract occurred three eyes Pseudomonas endophthalmiUs occurred in

patients wilh scleral necrosis Other less frequently

~~~~~~~ complications included corneal ulcers symshyb iris atrophy ptosis and thinned conj unctival

Dusenbery et al l 26 reported that 13 of 36 eyes treated with beta irradiation developed complications that induded epllheJi al defects or corneal thinning symblepharon caaractand corneal ulceration with an asSOCiated Pseudoshy

keratitis Four of the five eyes that were previously irradia ted

had an 80 complication rate Moriarty et al 127 reponed 11 cases of secondary funga l or bacteria l infections as a consequence of beta irradi ation-induced scleral necrosis

average latency between the beta irradiation and the of the complications was 145 years Seven patients

required a penetrating keratoplasty to remove the associa ted Inrection aT treat a fu ll-thickness o r incipient perforatio n

thinning or perforation can be treated surgically patch grafting usIng banked sclera Scleral necrosis

to both mitomycin l28 and beta irradiation 129 has also been successfully treated with hyperbatlc oxygen in selected rues that failed conjunctival grafting

Because conjunctival autograft ing offers a low rate of

pterygium recurrence and is free from long-term sight shythreatening complications it appears tha t autografting offers patients a safeI alternative when com paJed to beta iITadiatlon J2j Because scleral necrosis and possible late infectious compli cations occur years after the original surgery it is not surprising that numerous short- and Interm ediate-term studies deemed beta irradiation safe While it is debatable whether the reported complications from beta irradiation o r mito mycin therapy are a l an acceptably low rate the serious nature of these untoward late effects make conjunctival autografting a viable altershynative in the treatment of both primary and secondary pterygia

References I 8aJJillqu~-SOmen E Chan CC Green WTI COrneal epl lhIJal lJo n

depOSItion Ophthatmoklgy 90729 1983 2 Han5efl A Nom M Astigmatism and Ntface phfnomena in

pteryglum ActD OfIhthfllmol 58174 1980 3 yenoangson RM flelgylum in br~e Am J Ophthalma749S4 972 4 Detel~ R DhiT SP ~lerygium a goographlcallNdy Arch Ophlhalmol

78-4S 967 S Oldenburg JB (I aJ Conjunctlval pterygIa tntdlanhm of rornral

lop ographlc clw18es COflIM 9 200 1990 6 Gridley f] Peltm~n EM A lonn 01 vnable astigmafum inductd by

pseudll petyglum olIhalmk SUfg 11794 t 986 7 Un S el aI lht efftc1 of plerygla on contrast sensitivity and glut

ltlliablJJty Am JOphJIalmal I07-+ltl7 1989 8 Slvasllblamaniam P l1Cfygium in Ceylon Br JOphtilalmo SSS5

1971 9 Nom MS Prevalence of pinguecula in G re-eflland and in COpenhagen

and Its relation 10 pterygium md sph~rold degeneration Ada Ophfmmel 5196 ]979

10 Rasanayagaro Rr The j ncid~ MId ratlil distribution of pttJ)ghlD) in oSI MalaY1io1 To ltOphthalmol 50( NZ 2S56 1973

II Reja~ Jil Mal~) H Pterygium In Lima PeN All Ophlhalmtgt 1 8 1~ 1

1981gt 12 HUg~lHC Pwrygillm itS inddence hereaity and etiology Am I

Ophthalm()l 51)635 1960 )3 Cameron ME PttrrtJum throughout the W()lld Sprlngfitld U- 1965

Char]e$ C Thomas ] 4 MadltenzJf f1) e1 aI RUIlt ana1y~1s in thr deve lopment of pl ~rygil

Ophthgtlmo(IQ 99 IOS6 ]992 IS Colo n= Mf Pttry~ lum as an eall y indieaIO 01 ulualloiel 1n$Olat1on

a hypothemiddotds 8r I OpJUhalM 77734 1993 16 Hill ]C Maske It Pthc8Cnes1sect 01 ple-ryglurn l ye 3218 1989 17 Thylol HR ErlokPgy 01 dlmatlc droplet keraropthy and pterygium

8 JOpllthmoI641S4 1980 18 Karall Hor1gu~hl S Pterygium In weld~rs J3r I Ophd1almol 6-8347

1984 ]9 Moran DJ HoHoW1 FC Pterygium and ulfTavloret radiation a polt1ve

correlation 5r I Oplll1wlmol6ll 343 19S4 20 Sewl 0 Sealy R Pteryllill and carcinoma o f the CQnjWlctl~ nans

Ophthalmol Sot flK 88S67 1968 21 Oushlru N Tyter N Retd lW Immunoh istochemical e~idence Ihoal

pterygia arise om herelt limbal epitheUal b1sall lem ltlilli IngteU Ophthalmol IlI Sd H lon 1993

22 Tseng SCG ~I al Classiflca llon of conjunctlo-a1 ~ulgllf1es lor cornu ~a~ baStlt on Slem (~Il concept OpthQlmo elln Nortb Am 3595 1990

23 Dushlcu N John MK Schultz GS el al Plerygia pathogenesl$ ~ome3J

invasion by maUlX ~talloPrQJelJuse expl~ntng ilItertd Urobtl eplthe4la] bala] cells Nch Ophlhalmol 119695-706 ZOOI

Z4 Gokl~flll D1vld 11 PJerygmm andlU fflatloruh lp (0 the dry eye in the BanIU Br I Ophdwlrnol60120 1916

25 Wong WW A hypothesls o n 1hl pthogf~I~ of peryglums Am Ophllullmol )1)303 1918

26 ll nkenon 00 Hokama Y Shigemulil lA Immunologic basi~ fOl the pathogenests 01 plery(lum Am I OphrlulllllQ98 22S 1984

27 HKt F ShOpllllgh MG Winglets of rhe eye domlnant lransm~IOll of early Klu pieryf(ium of the coniunctiva I Mtd Gmer 2392 1990

26 Au~tll1 r J Il~obltc FA Iwamoto T tISlod)plast and elaslodysl1ophy as the palhologlt ~ses of ocular plerygla aud pinguecula

1759

_lI lliElWElIlTi AND lECONSTRUCTIVE PROCpoundOURES

Sectlon 2 Conjunctival Surgery

Ophth(1molofr90961983 Boudreau Sympm Cj Web Z et al Suppre~~ion oilCE and 29 Gallagher )10 GlannOudll A HeHlngton CS et al Hu man apoplOsj in na m m ary eplthehal cdh hy extracellula matttx Sc1mu

papi1lomavlru$ in pterygium Br I OplllhalmolS(7)7S2- 7M 200l 26789 1-8931995 30 G lOwers L Peel Jlamh E et al ProHferati ve icUvily and pS) 66 IltOIlUWI N lnataml T Sotowno C et a1 Growth factor mRNA and

expro ion in primary and r(OJlrem plerygI Ophth~lmolosr prOlein III pre~rveltl human ~mnlotlc membrJ)e Curr Ert Rei 108(5)985-9882001 20173- 1772000

3 0 Weimtein 0 Rogtsenthal G Zh~n H et al OvenlpltslIOIl o f pH Na 8K Hwang JH Kim jC e aI Mal)~~ of hullan amnlOl k rumor SUpples$OI tcne in plI~rygia Eye 16(5)6 19-02 1 2002 Melllbfan e com ponens as ptolei n~se m h blors for d t-elopmem of

32 l-logan MJ Alvado J Pterygiu m and plnguKUla t llOlOn lh elapeutic agen l of renl( lu anr kefatti TroplwblaSl Res 13 4 ~9-t66 m )Q05Copic STUdy A rc) OpIllJJnmtl78 114 1967 1999

33 Amari MW Rahl MiS Shukla BR Iwudoilisli( nut of pterygium 68 5hlmmura 5 Shlmazakt J OhaShi Yet al AnlllnflammalOf) ~ Hects of Br J Oph1Mlr1Ii)I51 ~1J 970 amnIotic membrane 1aflSplanlallon In ocular lumce dioordf~

Came ro n ME H I ~tology of pterygium ul electIOn mlcrltraquoroplC study 20408-4 13 2001shy

Sr J OphlJa1m)167604 1983 69 Plabhasawat P Barton K Burkert G tt al Comparison 01 conlunctiVll

Raluda IN Goswam AP Bhlltnagar NK HistopathOlOgy of ptel)glUm autograft ammotk membrane gratl5 and primary closure 101 Eye Ear Nose Thr(Q1 MOfllJgtly 47340 1968 pterygium exrulon OpIHJtamoloS) 104974--985 1997 Chi n CM Uu P Tan DT OcuJar rface dtangel 10 pteryglum 70 Tekin NF Kaynak S Saltn AO et ~l Pregtervoo h uman lmnlotir Coo-rea 21(1))3-42 2002 m embrane transplantatiOn in lhe llellnnent of primary pteryglIrll

37 BUIfI5 SIbull uhlal Mf Laby OM et at Incleraquoed nurn)er1 o f ma~ oU~ 0p[lQlmk Surg asos lZt6)464--469lOO1 in pterygia Am I Ophllullmol ll 9(2)236--217 1995 Solomo n A Pireltgt RTf Tgteng 5CG Am niorilt membrane Rkh AM er al A ~Implilleo y 10 uemo~ pterygia Atm Ophrllllmol nansptanlation after extensive emova l of primary anti rlaquounent 6739 1974 perygia Ophlhalmol)gy 10EI(3)449-460 2001

39 1I0stOIhal JW OlonolOg) oj pterygIUm tneupy Am JOphllnllmol 72 Ma DHmiddotK Stgte Lmiddote Uau 5middotB fl 011 ilmniOlk membratle gran fot 3616011953 primary pterygium oomp1lrlSon with wnjunctlyal aUloga ft and

40 Jaros PA DeLuIse VI fingutcI)ae and plerygia SII Ophllw moI 33H topical m ilomycin C trUlment Br JOphl l lmo 84 973-978 20C10 1988 73 Kl m jC Lee D Shyn KH Clinical usc$ of human ~mnlOllc m~mbr1nc

0 Adamh AI Starck T Kenyon KR TIle m anagement of pterygium fOI oCU laf urace d sease$ In Usgt JH ~dllor A dvances In conre~1 Opllhalmol Cli North Am 36 11 1990 rtstltffh New York 1997 PI~num rr~ pp 11 7-) 34 Kenyon KR Wagoner MD Helllnge r ME ConjUtlctiYal autogra ft 7lt Shlmlukl J Shinouki N nubOla K Transplantation of ~mnlOlic traniplantaUQn lor oldanod and recungtent pcerygium OphrJa1molatr ml mbrane and limba1 ulograft or patfntlt with recurre nl pteryglwl 92I461 19SS a~SOlt1lted wil h ~ymblepharon Br I Oplhalmol S223S- UO 1998

U Small RG A Ilaquo h nique lOr remoiii of plerygllm Ann Ophhitmol 1S Laugh rea PA Alen l5n D Lamella ktfalOplury in he managemem a 9) 49 1977 rECU n ent ptel8ium Opirthlllm( Sws 17106 1986 Y()IJJIgsoll RM II~n~ntt of pterygium after elltision Br I OphtJoumoi ion LT RH fisn JR Lamella keTalopla)ry rm uCUrfem PIErygium 56120 1972 Vphthalmic SuIt 7]8 19 76

lt5 Sen OK Surger) of pterygium Modified McGavic1 tlaquo hnlquf Br I gt7 BWIn M ef al IrtcUv~ lyophiJi2td li)IUe (al I ~ mdlagt ~e atopluty ill OphlJalnwI54606 1970 recu n en t pterygium Am I Ophrhalmol 102222 986 Egtcapini H Pwyglurn exci~ iQll Am (Ophrh~lmQ6 879 1958 78 Tr1vtdl LK M355e) DB Rolatgl R Man agement 01 pterygium ndltI Krag S Ehlers N beirner la5el lIealment of pterygiUm A(fa reeunenee by grafting 1 h mucoul membJane from the mouth Am J Ophthalmol 70530 1992 UphUralmoi 68353 1969 ZaubemHIO H Pteryglum and I~ ecurrencr Am JOphOmlmoJ 63 1780 79 Wong WW Blt haviolt of kin grafts in trea (mefl( of recunent

19()7 plerygtum Ann 0 Ihrhalm()1 9)S2 1977 Aoouze At Meresl sclera lectlnlque fa prlmar) pteJ)g1um ng~[ SQ O linder K Hai L HG Halk G tI Mangfmenl of pt~rygU 1houkf Ophthalmic Sulg 2Q892 1989 l hiollpa be used Ann OplrthamtJI 10 853 1978

50 Malnon V SUIg1ry 0 1 pleryglum by conjunctlyal pedide fLtp Am J so Ehllk h D IlK m3nagenwnt oj ptlaquoygIWJl OpIhalmic ~~ ~~ I OphUr~lmol6l 1778 1967 82 Gerde L5 Miillilgemen of plt ryg um alonS Iht Metitan Wiloon SE Bourne WM ConjurK1yal Z-plaSty In the rutmenlof Mtd 179782 1986 ptt ryglum Am I OphtJullmoll063SS 1988 83 KleIS W Pieo G Thio-I~pa Iherapy to prevent pGlt1operaue 11

52 510cka FW OperatIOn iar re moval of pterygIum Atth Ophtha mol occun ence and neovascularlUtton Am I Ophlhalmol 76371 27925 1942 Asregadoo ER Surgery thio tepa and corticost euroroi d In he treatmltnt

53 McCoornbe$ JA HitsllW h bcll GP Slidm g conjuncllval n~p fof the of ptery gium Am JOplgthQlmol 74 960 1972 treatment 0( primary pierygium Ophthalmokg) 101169 1994 85 C hM C W el al TrabeculeclOmy with somuhantOus lopical ~ppIIClt

le i G Swgery for pterygium U$ing a conllJnctjY~l peduncula te flap 01 mi tomycin-pound In rdrlClory glaucoma OCIIlar Iharmltl(ol6175 $lide Br f OpirlwlmoJ 80(1)13---34 1996 86 DoIr RT New f1ndulgllO the phaflnaCltJ~inetic f1)luboll c InoJ drugmiddot lewilUen 5 A ~ndml~ 111al o f ooojunaiva l autogf~flng fO Icshtllnce apect~ of mi tom)cin C s-rnin Oneol I S32 19 88 plerftium In he Hoplo OpJnlHllmoJDg) 96 16 1 2 19a9 j(un llomo N Mori 5 Slud~~ on lhe pteryg1um Pan of tfurrnJllof

SO Allan 805 It al Pterygium ~dilon wih conjunctlyal aut08afnng an the plcrygium by milo m )(lnc InStWanoo Acta Soc Ophclalrnollptl

effOCliYl and $afe l ectvllqul B JOphJgttllmol 11698 1993 67601 1963 Mguelredo RS Cohen (I GomnJAP et al Conlufl(twal 3ufOgraft IOf 88 Singh G Wilwn Mil rOlie t CS Mllomydn eye du1p$ ~I pltryglwn surgery how well dots it prevenl recurrence Ophlh almic pwygium Ophthalmology 9581 3 1988 SUfg Lastn 2899- 104 1997 89 Singh G Wi~n Mil r Oolc a Long-te rm followup 5rudy of

58 Dad~ya S Malok KPS Gulll ani SP Pterygiu m surgery conlunctlVal mito mycin eye drops iU ad luncllw lWlnneot fo r pterygia and 111 rotation autograft ~rsUI conjunctival autogra tl Ophthalm ic SUr$ LruffS coropuison with conlunc1lval autograft tl3n~planL1tlOn Cornell 33U9-274 2002 9413) 1990 AI Faye~ MF Llmbal eflUS conjunctiva l autognfl uansplantatian (or 90 advancro md teltUnem pleryglwn OphlhltlmoJosy 109 1752-755 ZOO2 0

ltgtG Slack T Ken yon IltR 5efRllO F ConIUnct autograft fo primary and rewn en pterygia surgical t llthn~uc and probl~m management Cameu 10196 199) t ~almenl o f recufJfnt

6 0 Vrabllt MP Weuenthil RW Elsong 5H SuboonlunctJal fibrrn is ahe r 93 RO~OIhal G t t al The mitomycin in p teryulD WileI) Ann

w nj unCtila[ autograft Cornea 12181 1993 Op1oJtalmol25427 1993 I

Singh G Pterygium In Ute tropics OphhollMklsr 97542 1990 Chayakul V Mllomyc)n In u euinl p l ~rygium Ophthalmologr 96399

63 Fu~uda K Chlkuoa T Nakamura M et 11 Dlfferenl1a1 dlmibution of 1989 mb(hotinl of the balemem membrane campon~n1S type V collag~n 9S fruchlmiddotPery Jlhar 1-1 The lise of low-dose mltomyctn C ~~OO I and laminln iUlIong the amnlollc membrane cornea and conlunctiva of recurrent pt~l)giurn Ophrlla lmology 101(4)751-76Z UlmeltI Hi71_79 1999 96 Cb~n 11 ArtYalU RG K U V er ai A nndomlzed trial campaing Kurpalu~ MA Daneshar C Davenport J CI 31 Human corneal IlIltomydn C and conlunctwal autograft aft er exdllon of pr1mar)

1760 epithelial cd JeioolOn to l amlni n~ Curr E~ Res 19106-11 4 1999 prcrygium Am I OphrhalmQ 120(2) 15 1-160 1995 -

Nwokara GE Ro it of m tomyoo C in pterygium ~u gery

1993

Haras1ka S e1

MaN PS Coolunal~1 ilUlograft ~~ topical mllo myctrJ C m ttUuncnt of pterygium EYf II 7900-792 1997 5upr A Who shOlId n1ccive 01110mydll-C after pteryglum surgery7 OplllhllmolotY99 I 64s199~ Vuoanoucnl U tI al Sderomabltla ~urnably due to milom ydll C lnst1JJgtorton ~tI~ pterygium uclslonlpn I CIi Ophlhlllmol33 139 1979 Hlyaukl S lwn Nagali Cl al Lale rompHcaUons ailrl pleryglum excision with high dO$e mllomycfl C mstillatlon B JOphlhamol 84(9) 108 1- 1082 WOO llut A DmoV1clcQJup B Lnsnllanon of InJlomyctn C dter recun~1

pn1rygiurn iwgery DIll OphtJwlmol6(3)264-6 J996 Rllblof~d RS el a ~riow compUcnlons of lopica l wIlOfll)cinC aile pterygium Slllamp~ry Oph~991641 1992 R~blnIeld R$ Mllontydn-C -ttl pteryamplwn ud~lOn Ophfhrllmo4og 1()()977 1993 ffUChlmiddotlery J SlganOi O I~I M I nUilopta tl~ ap pliCiition of topical mitomycin C foe pleryglum surgery OpluJulll1lQogy 10367+-677 1996 Clno-Pura J DiuUopl~ M Maloonado ~O tT a1 Prospective trial of rIua~fmiddote molomy(1n C in 111 ~alOlenl o f primary pterygiu m 8t J0pI01hllImo l 79(S)439-4 ~ J 1995 MasrropuqlU l Ctrplnf to P CIncaglin M ct aJ Long Itnn TeSlln of lnulDpflIve mllomydn C In Iht utalment of f=1 pltryglum 8t JOphtMmof 802-83-291 1996

bull Cardillo )A A)ves ~ ArnblOiiO LE 11 ll Stnglt ImrilopeaOve ippUculon YeISU pomgtperlli~ Dltoruydn C f)t drops In plltrypum fWltry OpJIllullmoiogy 102(1 2) 1949- J9S2 1991 Hdal M MtSSlhi N Ama~m A t l al Infuopcnuhf miTOmCIn-C ttJU poilOperi l1t topal mhomydn-C d rop fOT the Iooent of pttrygium Ophtlwbnl( Sur tIscf 27(8)6N- 6 78 1996 MMUllnamp CA Kloeu PM ou MD el ll Intnoptla tivt mitomyci n III primary pterygium excblon i prOipec1lvt landomlzld trilJ OphJIQlm(lllIr 104844-1148 1997 RublnIrld RS Stein R) Topiul mltomyltJl-C for p t ~rygill is ~ingle application appropr1itf Oplltlral mk 5uTg L(IJUJ 23662-669 1997 IuD OSC W008 AKJ( fin OSP ~ II Intraopctllfvt mitomycin C 10 prtltnt rtCU~cr of pleryglum afte r excision OphrJmJmtJl0tr 105901-9051998 Mullu IM $obtcl G ra tar Tel A comparatj~ sfld of rlaquoufrenl JM~um WlIery IllUbai conjunctiva aUIOKnh tRllsplilfll3lion

~J$U$ mitomycin C With (oniunltllVal Oap OphllwlnrolltltY 1068 17-a21 1999

I ll Dougherty Pl Hafdten OR UndsUom ill Co~leraJ mflTlIk~r pterygium surgery oWng IlnpoundJe Imrlopentjlle lIppUcat10n of mltomydn middotC Cornea IS(S)S37-S40 1996

II~ Oideya S KamJesh Intrloperaltve aaunorubctn 10 p~nt the IKUlWlce of plerygium _fte exdslOn Come 20(2)172-174 2001

115 Dad~lI S Kamlc~h Khu rana C CT II fntJaoperatlve daunorubldn venus conjunCtiva l aUlogtaft In pl1Inaly pletyamplulD twampcry Comtil 2 1 (8)7~769 2OOZ

J16 Tons tCK lan1 MM Rubenfeld S Celtulu chUJgS In tht conjunct afte wonriurt) 90 treatmenl fo r plerygtum Am I RoentgmollWlium 11m NUCI -fed 106843 1969

111 IahfUSII F DJna R Poslopcalt~ bl1Jo dliUon ll1lItrotfl of plecylium Int111Ddigtt Onevl Biol Ph)$ 9679 1983_

118 Hfbsleln AU DonQltgta n JIlt Plfrygium removal A IKtUllquc 10 pevenl ecum ltKe B1 OpltMlmoI52162 1968

119 Sinha k Comblntd mrgIeamp1 and bl1lI rltlllat1on trtatcltnt of pteryglumlndio PraC1202SS 1967

120 PlI)lni 58 t l aI Mnllg_lI o f plerygluD Wit h SUfltcy and adjadon Olelapy [IIQ(1QI Onc( Bioi Ph~ 28101 1994

121 Pinkerton 00 Swgklll Vld strontium trtatmenTof pletyglmn KIJtnce and Jem changes Age SUtlstiCll OphthalmIc Surs 10H 1979

IU Maclltenzk FD tt al RKUJTffitt le and complcadons ahu beu ImdlaTion for plt ryKiI OpJIrhGtmoJorr 981716 1991

12J Aswad Il0l 1 Baum J Optimal droc (QI pDSI Optfl dY irraltliatton of plerygill OphthQlmoIogy 94 I ~SO 1981

124 Levlnc OJ Sdfrltll complicaliol1 following bela Inadlltion AItII Ophtlialmoll l 21016 1994

125 Tur KH Consllble U tale compUcallOm o f pottryglum licaUrtenl 8t I Ophlhormm 64496 1980

126 Dwenblaquoy KE et aI Bet~ lnadlation of ~nl pterygia remits and com pllCli tlons Tm Radlol Onw181c1 Pity 243 15 1992

127 Mof1 any AP t l a1 Se-v t (OlmeoKJtlaJ Infeoctkln _ A COUlplkatlon or betll Imtdla lion ldellI OKIosis fonowtng pu ryslum ud~lon Atfh OphthQlmoII1I 9~ 7 1993

123 l1yer II Mudu FM 5ob~ti G Hypezbutc oxygen therapy fOI OIllomydn C-Induttd K leul nCOO$ii OplJthalmc Suig Laun J3(1 )~I 2002

129 Gretn MO Branntn Al Hyptlbuk ocygen therapy lox blt-nodlltlonmiddot indUCed Klefl l otaOiIs 0pI1J~ lOl(7)lOJ8- 104 I 1995

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