Management of Pterygium

Management of PterygiumClinical

Dr. Vidya Anandam, MS, Aravind Eye Hospital, Madurai

A very red, inflamed, fleshy progressive pterygium is more difficult to manage than a thin a vascular, non – progressive lesion.

Medical ManagementThe main goal of medical treatment is to relieve the patient of the inflammatory symptoms and to minimize the continuation of chronic irritation.1. Lubrication with artificial tear drops or

decongestants provide short term comfort and mild cosmetic improvement.

2. Topical steroid drops and ointments add an additional level of comfort, but long term application is fraught with potential complications.

3. Vasoconstrictive agents decrease redness and improve appearance.

4. Antihistamines added to the decongestant drops aid in the removal of histamine associated edema and itching.To prevent progression, some authors have

advocated the use of ultraviolet blocking spectacles against both UV-A and UV-B, on the basis of the results of their epidemiological study.1

Newer Therapies for Pterygium• FumagillinanalogueTNP-470,apotentanti-

angiogenic compound has been shown to have marked inhibitory effect on pterygium fibroblast proliferation.

• Reports demonstrating inhibitory effect ofVitamin D3 and Tranilast ( a keloid therapeutic drug) have also been published.2

• Short term efficacy of non steroidal anti-inflammatorydrugslike0.1%Indomethacinand its superiority to topical steroids have been demonstrated.

Surgical ManagementIndicationsforsurgeryasadvocatedbyZeigler• Progressivepterygium• Visualobstruction• Symptomatic,inducedastigmatism• Motilityrestrictioncausingdiplopia• Cosmeticdisfigurement

Recurrenceisthemostproblematicoutcomeand its prevention forms the motivation for evolving different surgical techniques.

Principles of SurgeryInprogressivepterygium,thereisactivefibroblastsadvancing above and below Bowman’s layer destroying it and superficial stroma. The fibroblastic cell invasion must be surgically halted attending to 4 basic principles.3

1. Preventionoflossofcornealtissue2. Removalofsubconjunctivaltissueinanarea

greater than that occupied by the pterygium.3. Coverage of exposed sclera with flap of

conjunctiva wholly free of subconjunctivaltissue.

AnaesthesiaConjunctival surgeriesmaybeperformedusingtopical anaesthesia, however peribulbar or retrobulbar block would be more appropriate. General anaesthesia is reserved for paediatric and uncooperative patients.

Resection TechniquesVarious procedures known to us are avulsion, simple or bare sclera technique, excision andclosure of bare sclera, transplantation and grafts (conjunctival,amnioticmembranegraft,buccal,mucosal membrane).

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Avulsion• AtechniquepractisedbytheancientGreeksis

avulsion of the pterygium.• Itscontemporaryproponentscontendthatthe

operation is simple and avoids accidental, deep dissectionintothecorneawhentheapexofthepterygium is removed.4

• The bulbar conjunctiva at the edge of thescleral portion of perygium is incised with westcott scissors and this portion is freed from the underlying sclera by blunt dissection.

• The freed portion of the pterygium is thengrasped with toothed forceps and torn from the cornea and a second forceps grasps the perilimbal tissue away to give countertraction.

• Residualtissue isscrapedfromthe-cornealsurface with beaver blade and surface is then polished with a diamond burr.

• Therecurrencerate(23–75%)issimilartoother techniques for primary removal.5

Simple Excision (Bare Sclera)• One of the most popular methods for the

removalofprimarypterygiumisexcisionofall remnants of the pterygium, leaving the underlyingbarescleraexposed.

• ThismethodwasdescribedbyD’Ombrainin1948.6

• Sharp dissection from the corneal side andfrom the uninvolved perimeter of normal conjunctivaisnecessary.Thecorneaisleftassmooth as possible, and all of Tenon’s capsule frombeneathandpterygiumisexcised.

• Bare sclera excision can be started from thecorneal apex (A) or by incision around theconjunctivalbodyofthepterygium(B).

• Theexcisionofasuperficial layerofcornealtissue at the time of pterygium removal was recommended by Castroviejo. Along witha superficial keratectomy, his procedure of choice for recurrent pterygia included removal of all corneal and scleral vascularization in the area of the excision.While emphasizing theimportance of not weakening or perforating the cornea, he described a shallow, smooth

dissection of the fibrovascular tissue comprising the pterygium and any opacification of the cornea.

• Superficialkeratectomytechniqueofremovingpterygium along with a minimum of scarred underlying cornea.Careful, sharpdissectionwhile maintaining gentle perpendicular tension on the pterygium will minimize the keratectomy and completely excise thepterygium from the cornea.

• It iscommontopursuemeticulousexcisionof all abnormal tissue, including cleaning the limbal site with a sharp surgical blade and polishing the area with a diamond burr. The goal is smoothness of the surface of the excision, not the complete removal of allopacity.

• There is a significant body of literaturesupportingthebarescleratechnique.Oneofthepilotstudiesreportedtheoutcomeof100bare sclera operations and noted a recurrence rate above one third.7

Excision with Primary Closure• The concept of undermining the adjacent

normal conjunctiva, with presumably lessultravioletlightexposure,andreapproximatingthe wound margins is finding renewed interest.8

• Rotationofaflapof superiorconjunctiva isthought to prevent recurrence and provide a smooth surface at the limbus to encourage proper tear film distribution, A technique of slidingconjunctivalflaps fromboth inferiorand superior limbus to close the wound has been reported to have a 1 –year recurrence rate ofonly5%.9

• Sliding conjuctival flaps can be used toprimarilycloseapterygiumexcisionsite.

• Withthe“Merestsclera”technique10, the head and mid body of the pterygium are excisedand a tenonectomy is extendedbeneath theconjunctiva to the adjacent rectus muscle,particularly in young patients or large lesions. Relaxingconjunctivalincisionsaremadeboth

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superiorly and inferiorly along the limbus, and the conjunctiva is closed primarily andmeticulously.The rare recurrences (2.1%),occurred only in 2 cases with wound infection andin15caseswithwounddehiscencefromthis large series.

Transplantation of the Head of the Pterygium• Among the early theories of pterygium

recurrence was the idea that the head of the pterygium was the cause of its growth. Mc Reynolds’ operations was based on thistheory, wherein the head of the pterygium is dissected from the cornea and transplanted into one of the fornices.

• A method of conjunctival z-plasty wasdescribed for primary closure which was later modified.11 The modified method consists of placing a flap of normal tissue between the body of the pterygium and the corneal limbus. Nodataonrecurrenceusingthismethodareavailable, but the authors argue that the normal tissue acts as a barrier to the regrowth of the pterygium and preserves the superior bulbar conjunctivaforuseinaconjunctivalautograftprocedure in the event of a recurrence.

Transposition Flaps• Atranspositionconjunctivalflapisabipedicle

flap cut from healthy tissue and transferred to the site left bare by a resection.

• Theseflapsfollowthesameprinciplesofslidingflap.9

• Advocated by Smith mainly for treatment of recurrent pterygium, a transposition flap is obtained by performing two 120 degreeconcentric incisions parallel to the limbus in the healthy tissue of the meridian opposite a resection.

• The first incision is made 1mm from thelimbus and second one in accordance with the sizeofconjunctivalresection.

• AfterdissectingconjunctivafromunderlyingTenon’s capsule with scissors, the flap is

transposed to the opposite meridian respecting the upper and lower vascular pedicles.

• Theconjunctiva is then sutured to thehostbed and anchored to underlying sclera with interrupted10-0nylonsutures.

• Main advantage of the flap is its doublevascular pedicle, which provides a faster revascularization and greater vitality.

Conjunctival Autograft• Conjunctivalautograftingpreventsrecurrence

byactingasabarrieradjacenttothelimbusandpreventingmigrationofnasalconjunctivafollowingbarescleraexcisionofpterygium.

• Anovelmethoddescribedthetransplantationof free autografts of superotemporal bulbar conjunctivafromthesameeyetoclosewoundsafter the excision of advanced or recurrentpterygium.12

• They used this method on 57 eyes of 54patients,nearly80%ofwhichhaverecurrence.Mean follow-up of 2 years detected onlythree (5.3%) recurrences after autografttransplantation. The authors emphasize taking minimal subconjunctival tissue, to preventscarring and retraction of the graft.

• Thegraftisslightlylargerthanthepterygiumsite.Cautery spots areused todelineate theinvolvedareaofconjunctivatobeexcised.

• Sharp,superficialexcisionoftheheadofthepterygium from the involved cornea to the limbusisdone.TheconjunctivaandTenon’scapsule are bluntly and meticulously dissected fromthehorizontalrectusmuscle.Conjunctivais secured to the sclera with absorbable suture (eg.,8-0Vicryl)onaspatulatedneedle.

• Calipers are used to determine the size ofconjunctivalgraftrequiredtoresurfaceexposedsclera and horizontal rectus muscle.

• Calipers are used to determine the size ofconjunctivalgraftrequiredtoresurfaceexposedsclera and horizontal rectus muscle.

• Theglobeisrotatedinferomediallytoexposeanareaofuninvolvedsuperiorbulbarconjunctiva.

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Dimensions are marked with several cautery spots,aslargeas15x15mmextendingtothelimbus.

• Freegraftsaredissectedasthinlyaspossible,taking minimal subconjunctival tissue. Ifthe graft is excised surface can be readilyidentified when the graft is repositioned. The donor site does not required suturing, but the conjunctivalmarginscanbeadvancedtothelimbus with two interrupted sutures.

• Thefreegraftistransferredintothereceipientbedandsecuredtoadjacentconjunctivaandepisclerawithinterruptedsuturesof8-0Vicrylor10-0nylonusedforthelimbaledgeofthegraft.

• Younger patients were much more likely tohave a recurrence, and all recurrences were noted by the patient within 6 to 8 weeks of surgery.13

Annular Conjunctival Autograft• Severecasesofprimaryorrecurrentpterygium

withextensivesubtotalinvolvementofcornealsurface may benefit from an annular graft modified from the conjunctival autograftprocedure.

• Afterextensiveexcisionofthepterygiumandsuperficial keratectomy with adequate limbal clearance of adherent pterygial tissue, a large rectangular conjunctival autograft fromsuperiorbulbarconjunctivawasharvestedandsplit into a large elongated strip. The strip was then sutured in an annular fashion over the area of limbal defect.

Amniotic Membrane Transplantation• Amniotic membrane is used in ocular

reconstruction surgery.• Thepterygiumheadandbodytogetherwith

subconjunctivalfibrovasculartissueisremoved.The denuded sclera is covered with a sheet of preserved amniotic membrane.

• An advantage of amniotic membranetransplantationoverconjunctivalautograftisthefactthatdonorconjunctivadoesnotneed

to be harvested from the superior bulbar area in the event of future glaucoma surgery.

• This procedure is also ideal for pterygiawith two heads or diffuse involvement. Recentlyamnioticmembranetransplantationtogether with use of limbal autograft has been successfully used to correct complicated and recurrent pterygia.

• Amniotic membrane transplantation aloneresultedinarecurrenceof37.5%inrecurrentpterygium. It was reported that amnioticmembrane transplantation with limbal conjunctival autograft alone resulted in arecurrenceof8.3%.

Limbal Autograft• Thereisagrowing body of data that corneal

epithelial stem cells are located at the limbus.14

• Thestemcellsgeneratenewcornealepithelialcells in addition to inhibiting conjunctivalepithelial invasion of the cornea.

• Transplantationof limbal stemcellsmaybenecessary for patients who have undergone multiple pterygium excision with extensivedamage to the limbus.

• When conjunctival autograft was comparedwithlimbalconjunctivalautograft(includingprimary and recurrent cases), it was reported that later had superior effectiveness for recurrent pterygia (no significant benefit for primary)15.

Lamellar or Penetrating Keratoplasty• It is not unusual after surgery for recurrent

pterygium to have significant residual scarring and thinning of the cornea. In such cases,lamellar corneal graft tissue can be used to replace thin or scarred portions of the cornea.

• Useofacornealtrephine(usually8mm)toincisethelimbustoadepthof0.3mmaftersuperficial excision is part of one lamellartechnique.16 The host bed is then dissected, with attention to creating a smooth surface. The defect is filled with a 0.4mm thickfresh donor button, sutured in place with interrupted10-0nylon.

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• The technique reported three recurrencesamong nine cases, after mean follow-up of 2 years. It was also noted the lamellarkeratoplasty is not a complete barrier against regrowth of pterygia, but recurrent lesions remained smaller with thicker underlying tissue, restoring normal anatomic features.

• In the setting of thinning and impendingcornealperforationorscarringofthevisualaxisof the cornea, penetrating keratoplasty must be considered. In this rare instance,amodifiedtechnique with decentration of the graft and careful suture placement in the thinned area is recommended.

Cut and Paste Technique• It is a novel, no suture, and small incision

approach to pterygium surgery, with the use of improvised biologically compatible glue.17

• Tisseel Duo Quick is a two componenttissue adhesive which mimics natural fibrin formation. This glue has two components. OneconsistsoffibrinogenmixedwithfactorXIII and Aprotinin.The other componentis thrombin CaCl

2. All components were

prepared from banked and well controlled human blood. Equal amount of components are mixed together. Through action ofthrombin, the fibrinopeptides are split into fibrin monomers. These monomers aggregate by cross-linking resulting in fibrin clot.

• Adhesionsbetweenpterygiumandsclerawassharply incised at the limbus and pterygium head was separated from cornea by blunt dissection using iris spatula. Thickened and keratinized portions of conjunctiva andunderlyingTenon’s capsule excised.Woundbed scraped to clean cornea and sclera; bleeding vessels cauterized.

• A free conjunctival graft of same size asnasal conjunctival defect was prepared atsuperotemporal limbus of same eye. Limbal edge of the graft was cut to contain a thin rim of corneal epithelium.

• The graft was moved to the nasal area andattached to the sclera with glue. Properorientation maintained with epithelial side up and limbal edge towards the limbus.Whenglue was used, graft was placed with the epitheliumsidedownonthecornea.Itwastothe nasal side with limbal edge facing towards the wound.

• Onedropofthrombinwasplacedonscleralbed and one drop of protein solution placed on the graft. Thereafter the graft was quickly flipped over the sclera and smoothened out while the fibrinogen was activated by the thrombin forming the fibrin glue. After the graft is positioned, there was 30 seconds tosmoothen out graft and press it gently to the scleral bed attaching the graft firmly.

• A recurrence rate of 14% was noted in thestudy.

• Useoffibringlueforgraftfixationinpterygiumsurgery is a safe, fast method and does not have any side effects. This new technique of pterygium surgery decreases post-operative pain and surgery time.

Intraoperative Complications in Pterygium SurgeryThreemajorcomplicationsthatcanoccurwhileperformingpterygiumexcisionare• Perforationofcornea• Perforationofthesclera• Injurytothehorizontalrectusmuscle

Perforation of cornea and sclera may occurwhile excising recurrent lesions because theremaining tissue can be iatrogenically left very thin.

The most important aspect of dealing with corneal perforation is its prevention and preparation when such a problem may arise. Dissection should be meticulous. If cornealthickness is suspected to be extremely reduced,surgeon should perform a peripheral lamellar keratoplasty.

Small scleralperforationcanbeclosedwith7-0vicrylsutures.Iflargerdefectoccursthearea

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is repaired by using a graft of corneal tissue and covering it up with a conjunctival sliding flap.Suchgrafttendstobecomeopaqueandsimulatescleral tissue.

Injury to extraocular muscles can occur onaggressively recurrent pterygium with prominent scar tissue formation in tenon’s layer.

Other complications documented areinfectious scleritis, granuloma formation, Dellen formation, iatrogenic astigmatism, amputation neuroma, symblepharon.

Surgical Complications of Conjunctival autograft1. Graft edema may result secondary inadequate

debridement of the graft. All Tenon’s capsule remnantsshouldbeexcisedtoavoidretractionand postoperative oedema.

2. Graft necrosis occurs when the graft is misplaced epithelial side down or if the recipient bed is avascular secondary to irradiation.

3. Sclerocornealdellenoccursduetoanoversizedgraftorpersistentedema.Excessiveuseofthediamond burr or blade to resect the head of pterygium produces a rough surface with poor lubrication and subsequent dellen formation.

4. Epithelial inclusion cysts are typically transparent and encapsulated. They appear 1 or 2 months postoperatively and may be produced by inclusion of epithelial debris beneaththeconjunctivalgraft.

5. Subconjunctival hematomas usually subsidespontaneously without consequence, exceptfor short term cosmetic appearance.

6. Subconjunctival fibrosis may occur at thedonor site. The fibrosis is trigerred by the abnormalexposureofTenon’scapsuleandcancause problem that is usually only cosmetic. Subconjunctival fibrosis and granulomaformation can occur in the recipient bed, principally due to incorrect technique leaving Tenon’slayerexposedorusingtoofewortootight sutures.

7. Corneoscleral thinning is more frequent inrecurrent pterygia. Tendency to use deep keratectomy to remove the head of the pterygiumisthemaincausethoughexaggeratedscraping,polishingorexcessivecauterycanalsoproduce it.In a noted article published, complications

seenwithconjunctivalautograftwereclassifiedas–4cases(2.88%)developedgranulomaatdonorconjunctivalsite,3cases(2.16%)hadconjunctivalcystonthegraft,1case(0.72%)developedscleralthinning.18

Adjunctive TherapyA number of adjunctive therapies have beendescribed to decrease the risk of recurrence after the surgical removal of a pterygium. Each has its attractive features, but none is without drawbacks.

Cautery• Withtheknowledgethatbloodvesselgrowthat

the operative site contributes to the recurrence of a pterygium, several people have advocated the extensive use of intraoperative cautery,particularly at the limbus, to augment the surgical removal of the pterygium.

• Excessivecauterycanleadtotheformationofhypertrophic scar tissue and scleral thinning and necrosis.19

Laser Therapy• The use of the Argon laser in selected

postoperative cases has been described. The technique of applying 50µm spots to earlyneovascular fronds the limiting power settings tominimizeconjunctivalepithelialdamagehasbeen reported.20 The recurrence rate is around 12%.Complicationssuchasscleralnecrosis,scleromalacia, secondary iritis and cataract have been reported.

• Excimerlaserwasusedtoablateirregularitiesin the bare scleral surface after pterygium excision.The recurrence rate was 91% (20cases) at 1 year, which the authors attribute to thebarescleratechnique,nottheexcimerlasertreatment.

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Corticosteroids• New vessles often herald the recurrence of

a pterygium. Postoperative use of topicalcorticosteroids inhibits the inflammatory reaction and may reduce neovascularization of theoperativesite.Somecorticosteroidshavedirect antiangiogenic effects in addition to their anti-inflammatory effects.20

• Severalauthorshaveadvocatedtheirusefourtimes daily for 2 weeks after the healing of the corneal epithelial defect.21

Thiotepa• Thiotepa is a nitrogen mustard alkylating

agent with antimitotic properties. It is aradiomimetic agent that presumably obliterates proliferating vascular endothelial cells.

• Itsearlyusein30patientsinJapanfollowedbare sclera excision with the application of12,000 (15 mg in 30ml Ringer’s solution)dilution of thiotepa every 3 hours for 8 weeks. The recurrence rate is reported to range from 12%-16%.

• Reportedcomplicationswiththiotepaincludeprolongedconjunctivalhyperemia,irritation,allergic reactions, bacterial corneoscleritis, and permanent eyelid depigmentation, especially in darkly pigmented patients.22No systemictoxicityhasbeenreported,butthesesideeffectshave deterred many ophthalmic surgeons from adjunctive use of thiotepa after pterygiumsurgery.

Beta Radiation• Inhibitionofproliferatingcellsinthewound

bed can also be accomplished by beta radiation, which presumably reduces mitosis in rapidly dividing vascular endothelial cells.

• Irradiating the rapidly dividing endothelialcells of a pterygium dramatically slows their proliferation, while sparing the adjacentmitotically inactive cell populations.

• Betaradiationdoesnotappeartobeeffectiveas a sole treatment for established pterygia.

The introduction of strontium applicators for ophthalmologic use in 1950 broughtstronticum–90intousedasthestandardpurebeta (no gamma) radiation source. In mostsubsequent studies, recurrence of pterygium after surgery and beta radiation ranges from 0%ro16%23.

• Standarddoseisintherangeof1000to3000rad. A shield is left in place on the applicator to prevent ambient radiation from encountering the cornea, sclera, or physician.

• Two 0.5mm thick, high water content, softcontact lenses have been used to restrict the highest dose to the outer 1mm of the wound bed.Ifadoseof1800to2200radisappliedtothe pterygium bed, the anterior surface of the lensreceives70to90radwhiletheposteriorretina receives only 4 to 8 rad.

• Applicationofbetaradiationisprobablybestdone in the immediate postoperative period.

• Cataractformationafterbetaradiationiswellknown. Ionizing radiation can damage theequatorial cells of the lens epithelium, giving rise to the changes that appear in the lens fibers and in the posterior subcapsular region after beta radiation.

• Other complications after beta radiationtreatmentare lesscommonlikeconjunctivalhyperemia, scleral ulceration, symblepharon formation, ptosis, iris atrophy, corneal ulceration, bacterial corneoscleritis and panoophthalmitis.24

Fibrin Glue• Fibringlueisabloodderivedproductthatis

absorbable, relatively easy to use, and can be kept at room temperature or in a refrigerator.

• Althoughtheuseoffibringlueasabiologicadhesivewasfirstintroducedin1909,itwasnot until 1944 that Tidrick et al, used fibrin forskingraftfixation.25

Also it was in early forties that fibrin glue was introduced to Ophthalmology to fixatepenetrating corneal grafts in rabbits.26

8 AECS Illumination

• Fibringlueisabiologicaltissueadhesivewhichimitates the final stages of the coagulation cascade when a solution of human fibrinogen is activated by thrombin (the two components of fibrin glue).27-29

• Fibringlueincludesafibrinogencomponentand a thrombin component; both prepared at a blood transfusion center or from patients own blood30 or obtained as a commercially available preparation.

• Whenitisderivedfromindividualvolunteerdonations, it may have a low concentration of fibrinogen.31 The commercially available products are produced from pools of plasma, usually contain yields of fibrinogen and consequently, produce firm coagulams. Unlike cyanoacrylate glue, fibrin flue forms a smooth seal along the entire length of the wound edge and thereby provides greater postoperative comfort to the patient with complications.32

Mechanism of Action• Whenhumantissueisinjured,bleedingensues

and then ceases due to formation of a blood clot. This is the initial mechanism of natural wound closure.

• Clot is formed as a product of the finalcommonpathwayofbloodcoagulation.Fibringlue mimics this coagulation cascade resulting its adhesive capability.

• Once the coagulation cascade is triggered,activated factor X selectively hydrolyses prothrombin to thrombin, fibrinogen is converted to fibrin. Thrombin also activates factors XII (present in the fibrinogencomponent of the glue), which stabilizes the clot, by promoting polymerization and cross linking of the fibrin chains to form long fibrin strands in the presence of calcium ions.

• This is thefinal commonpathway forbothextrinsicandintrinsicpathwaysofcoagulationin vivo, which is mimicked by fibrin glue to induce tissue adhesion.

• Thereissubsequentproliferationoffibroblastsand formation of granulation tissue within hours of clot polymerization clos organization is complete two weeks after application. The resultant fibrin clot degrades physiologically.

Methods of Preparation• Numerous techniques have been used to

prepare fibrin glue, either from homologous or autologous plasma. The autologous source avoids any possible risk of viral transmission.

• Homologous fibrin glue is prepared fromdonors screened like other blood products, followed by inactivation of viruses by solvent / detergent treatment.

• The plasma is centrifuged to produce aprecipitate containing fibrinogen and a supernatant containing the thrombin. The precipitate is resuspended in a small volume of a supernatant and used as the fibrinogen component.

• Thesupernatantisfurthertreatedbyclottingto convert residual fibrinogen to fibrin followed by filtration to isolate the fibrin. The resulting serum is used as the thrombin component.

Various methods of preparation• FibrinogenmodifiedHartman’sprocedure• ThrombinArmandJQuickmethod• Fibrinogenrichconcentrate• Preparationduringemergencyneeds

TisseelDuoQuick(Baxter,Vienna,Austria)is a two component tissue adhesive which mimics thenaturalfibrinformation.Ithasbeenusedinneurosurgery, plastic surgery, ENT and ocularsurgery.This glue has two components. OneconsistsoffibrinogenmixedwithfactorXIIIandaprotinin. The other component is a thrombin CaCl

2 solution. All components are prepared

from banked and well controlled human blood. Equal amounts of the components are mixedtogether. Through the action of thrombin, the fibrinopeptides are split into fibrin monomers.

Vol. XV, No.1, January - March 2015 9

These monomers are aggregated by cross linking, resulting in a fibrin clot.

Thrombin concentration can be varied to regulate the speed of coagulation. Low thrombin concentrations(4NIH–U/ml)withslowclottingareused,forexample,inskingraftingwhilehighthrombin concentrations (500 NIH-U/ml) arebeneficial where almost instantaneous clotting is desired.Thedoublesyringeapplicator(Duploject)isusuallyadvocatedformixing,inordertoobtainpreciseamountsofthecomponents.However,thesealantcanbeapplied sequentiallyorpremixedthrough needles, spraying heads or catheters.

The glue does not stick to intact corneal or conjunctival epithelium. In ocular surgerysealing perforations in the lens capsule, treating conjunctival wounds and fistuals, adapting freeskin transplant in lid surgery, repairing injuredcanaliculi and sealing the wound in cataract surgery are described.

Advantages• Fibrin glue reduces the total surgical time

because time required to place the sutures is saved.

• Theuseofgluehasfoundtolowertheriskofpostoperative wound infection, contrary to conventional suturing. This can be attributed to accumulation of mucous and debris in sutures which may act as a nidus for infection.

• Mixturesoffibringlueandantibioticsarebeingused for local delivery of antimicrobial activity.

• It is well tolerated, non-toxic to the tissuewherever it is applied and has some antimicrobial activity.

• Thesmoothsealalongtheentirelengthofthewound edge results in higher tensile strength, with the bond being resistant to greater shearing stress.

• Fibrin glue is also an adjuvant to controlbleeding in selected surgical patients.

• It has a low incidence of allergic reactions.Howeveranaphylacticreactionsfollowingitsapplication has been reported. This reaction has been attributed to the presence of aprotinin in fibrin glue.

• Fibrin glue encourages the formation whenapplied to contaminated tissues. Chenet al, reported that fibrin glue failed to

demonstrate any bacteriostatic effects to gram positive or negative bacteria by verifying the size of the bacterial growth inhibition.

Disadvantages• Riskoftransmissionofdiseasesfrompooled

and single donor blood donors. This can be minimized to a greater extent by obtainingblood from screened donors.

• It is expensive and autologous donationrequires at least 24 hours for processing. The resultant product often has variable concentrations thereby resulting in an unpredictable performance.

Referrences

1. Taylor HR, West SK, Rosenthal FS, Munoz B, Newland HS, Emmett EA, Corneal changes associated with chronic UV irradiation. Arch. Ophthalmol. 1989 Oct; 107 (10):1481 -1484.

2. Cameron M.Ultraviolet radiation. Pterygium throughout the world Charles C Thoman, Springfield, IL, 1965; 141 -54.

3. Jose I Barraquer. Etiopathogenesis and treatment of pterygium. Symposium on Medical and Surgical Diseases of Cornea, 1980; 533 – 40.

4. Zolli CL. Experience with the avulsion technique in pterygium surgery. Ann Ophthalmol 1979; 16: 125 – 134.

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5. Gibson JSB. Brisbane survey of pterygium. Trans Ophthalmol Soc Aust. 1956; 16: 125-134.

6. D’ombrain A. The surgical treatment of pterygium. Br J Ophthalmol. 1948 Feb; 32 (2):65-71.

7. Youngson RM. Recurrence of pterygium after excision. Br J Ophthalmol. 1972 Feb; 56 (2): 120 – 125.

8. Frabk A Nesi, Richard D Lisman, Mark R Levine. Smith’s ophthalmic, plastic and reconstructive surgery, 2nd edition, Mosby, St Louis 1998; 1173 – 1185.

9. Tomas T. Sliding flap of conjunctival limbus to prevent recurrence of pterygium. Refract Corneal Surg. 1992 Oct; 8(5): 394 – 395.

10. Anduze AL. Merest sclera technique for primary pterygium surgery. Ophthalmic Surg. 1989 Dec; 20(12) : 892 – 894.

11. Wilson SE, Bourne WM. Conjunctival Z-plasty in the treatment of pterygium. AM J Ophthalmol. 1988 Sep 15; 106(3):355 – 357.

12. Kenyon KR, Wagoner MD. Hettinger ME. Conjunctival autograft transplantation for advanced and recurrent pterygium. Ophthalmology 1985 Nov; 92 (11) : 1461 – 1470.

13. Sharma A, Gupta A, Ram J, Gupta A. Low dose intraoperative mitomycin C versus conjunctival autograft in primary surgery : long term follow – up. Ophthalmic Surg Lasers. 2000 Aug; 31 (4) : 301 – 307.

14. Shimazaki J, Kosaka K, Shimmura S, Tsubota K. Amniotic membrane transplantation with conjunctival autograft for recurrent pterygium. Ophthalmology. 2003 Jan; 110 (1) : 119 – 124.

15. Al Fayer MF. Limbal versus conjunctival autograft transplantation for advanced and recurrent pterygium. Ophthalmology. 2002 Sep; 109 (9) : 1752 – 1755.

16. Laughrea PA, Arentsen JJ. Lamellar keratoplasty in the management of recurrent pterygium. Ophthalmic Surg. 1986 Feb; 17 (2): 106 – 108.

17. Koranyi G, Seregard S, Kopp ED. Cut and paste : a no suture, small incision approach to pterygium surgery. Br J Ophthalmol. 2004 Jul;88(7) : 911 – 914.

18. TiSE, Chee SP, Dear KB, Tan DT, Analysis of variation in success rates in conjunctival autografting for primary and recurrent pterygium. Br J Ophthalmol. 2000 Apr; 84(4) : 385 – 389.

19. Rich AM, Kietzman B, Payne T, McPherson SD. A simplified way to remove pterygia. Ann Ophthalmol. 1974 Jul; 6(7) : 739 -742.

20. Krag S, Ehlers N. Excimer laser treatment of pterygium. Acta Ophthalmol (Copenh). 1992 Aug; 70 (4) : 530 – 533.

21. Zauberman H. Pterygium and its recuurence. Am J Ophthalmol. 1967 Jun;63(6) : 1780 -1786.

22. Kleis W, Pico G. Thio – TEPA therapy to prevent postoperative pterygium occurrence and neovascularization. Am J Ophthalmol. 1973 Sep; 76 (3) : 371 – 373.

23. MacKenzie FD, Hirst LW, Kynaston B, Bain C. Recurrence rate and complications after beta irridation for pterygia. Ophthalmology. 1991 Dec; 98 (12):1776-1780; discussion 1781.

24. Lentito W, Zaret MM, Rossigonol B, Rubenfeld S. Treatment of pterygium by surgery followed by beta radiation: an analysis of 256 cases. Am J Roentgenol Radium Ther Nucl Med. 1950 Jan; 81(1):93-98.

25. Panda A kumar S kumar A, Bansal R, Bhartiya S. Fibrin glue in ophthalmology. Anita Panda1, Sandeep Kumar2, Abhiyan Kumar3, Raseena Bansal2, Shibal Bhartiya Indian J Ophthalmol. 2009; 57:371-3.

26. Katzin HM. Aqueous fibrin fixation of corneal transplants in the rabbit. Arch Ophthal. 1946 Apr; 35 : 415 -420.

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27. Thompson DF, Letassy NA, Thompson GD. Fibrin glue: a review of its preparation, efficacy, and adverse effects as a topical hemostat. Drug Intell Clin Pharm. 1988 Dec; 22(12): 946 – 952.

28. Chabbat J, Tellier M, Porte P, Steinbuch M. Properties of a new fibrin glue stable in liquid state. Thromb. Res. 1994 Dec 15; 76(6):525 – 533.

29. Le Guehennec L, Layrolle P. Daculsi G. A review of bioceramics and fibrin sealant. 2004; Sep 13; 8 :1 – 10; discussion 10 -1.

30. Hartman AR, Galanakis DK, Honing MP, Seifert FC, Anagnostopoulos CE. Autologous whole plasma fibrin gel. Intraoperative procurement. Arch Surg. 1992 Mar; 127 (3) : 357 – 359.

31. Dresdale A, Bowman FO, Malm JR, Reemtsma K, Smith CR, Spotnitz HM, et al. Hemostatic effectiveness of fibrin glue derived from single – donor fresh frozen plasma. Ann. Thorac. Surg. 1985 Oct; 40 (4) : 385 – 387.

32. Sharma A, Kaur R, Kumar S, Gupta P, Pandav S, Patnaik B, et al. Fibrin glue versus N-butyl-2-cyanoacrylate in corneal perforations. Ophthalmology. 2003 Feb; 110 (2) : 291 – 298.