Deep Lamellar Keratoplasty

7/29/2019 Deep Lamellar Keratoplasty

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Deep Lamellar KeratoplastyUsing Viscoelastic Dissection

Edward E. Manche, MD; Gary N. Holland, MD; Robert K. Maloney, MD, MA

We describe a technique for performing deep lamellar keratoplasty using viscoelas-

tic dissection. Deep lamellar dissections of the cornea using viscoelastic sub-

stances (sodium hyaluronate) were performed on 4 eyes of 4 patients. One pa-

tient with keratoconus and another with corneal scarring underwent lamellar

keratoplasty using the technique as the sole procedure for visual rehabilitation. Two patients (2 eyes)

with opaque corneas underwent deep lamellar dissection with removal of stromal tissue to allow vi-

sualization of the anterior segment structures prior to penetrating keratoplasty, thereby facilitating

separation of iridocorneal adhesions as the Descemet membrane was incised. Deep lamellar dissec-tion was performed without complications related to the procedure in all 4 eyes. The 2 lamellar grafts

cleared completely, and both eyes achieved excellent visual acuity with spectacle correction. In the

other 2 eyes, deep lamellar dissection provided clear visualization of anterior segment structures dur-

ing incision of the Descemet membrane. Deep lamellar dissection using viscoelastic substances is a

useful technique during lamellar keratoplasty. Arch Ophthalmol. 1999;117:1561-1565

Lamellar keratoplasty is a procedure inwhich a donor graft is placed within a par-tial depth recipient corneal bed after a la-mellar resection has removed abnormalstromal tissue from the host. The proce-

dure can be used to restore the optical orstructural integrity of the globe; cur-rently,it is used most commonly duringtheplacement of tectonic grafts to restore nor-mal thickness to globes after loss of tissuefrom thinning disorders of the cornea.

Today, the procedure is used infre-quently for restoration of vision because itis technically more difficultto perform andhas traditionally yieldedinferior optical re-sultswhen compared withpenetrating kera-toplasty. Nevertheless, lamellar kerato-plasty has a number of advantages overpenetrating keratoplasty. With lamellar

keratoplasty, the patients endothelium re-mains intact, eliminating the risk of endo-thelial rejection, which is the most com-mon cause of graft failure followingpenetrating keratoplasty. Another advan-tage of lamellar keratoplasty is that the

structural integrity of the globe is bettermaintained than with penetrating kerato-plasty.

There are a variety of techniques forperforming lamellar keratoplasty.1-17 Tra-

ditionally, the lamellar resection has beenperformedmanually,using sharp andbluntdissection.2-6,14,15 Others have tried usingair dissection,1,9 microkeratome dissec-tion,10,11 dissection using the excimer la-ser,12 and hydrodelamination using sa-line dissection,16 all with varying degreesof success. Sun and coauthors17 de-scribeda similar technique they termed vis-codelamination for the treatment of bul-lous keratopathy.We describe a techniquefor performing deep lamellar dissection ofthe cornea that uses a viscoelastic agentto dissect all of the stromal tissue from the

underlying Descemet membrane and en-dothelium.

SURGICAL TECHNIQUE

Based on our experiences with these cases,we have found the following procedures tobeeffective(Figure). After determining theappropriate diameter of the tissue to be re-moved from the patient, a trephine, or a

From the Department of Ophthalmology, Stanford University School of Medicine,Stanford, Calif (Dr Manche); Department of Ophthalmology, Jules Stein Eye Institute,University of California at Los Angeles (Dr Holland); and the Maloney Vision Institute,Los Angeles (Dr Maloney).

SURGICAL TECHNIQUE

ARCH OPHTHALMOL/ VOL 117, NOV 1999 WWW.ARCHOPHTHALMOL.COM1561

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combination of a trephine and arounded blade, is used to create anincision of 80%to 90% thicknessintothe patients cornea (Figure, A). APaufique blade is then used to makea deep incision that runs parallel tothe stromal lamellae. This incisionshould start at the bottom of the

trephine incision, moving radiallytoward the central cornea, creatinga 1- to 2-mmpocket. The blade is re-moved, and a 25-gauge cannula at-tached to a syringe containing vis-coelastic material is introduced intothepocket(Figure, B).Theviscoelas-ticmaterial is slowly injected into thispocket. It is forced through the pos-terior stromal lamellae along thepathof least resistance, causing the Des-

cemet membrane to separate from theposterior stromal tissue (Figure, C).Once the Descemet membrane hasbegun to detach, thecannulaisslowlyadvanced into the space being cre-ated, thereby completing the dissec-tion(Figure, D). Corneal scissorsareused to remove the diseased patient

tissueby cutting along thegroovecre-ated by the trephine. A modificationof this technique can also be used incorneas with severe opacification. Astab incision can be made into thecornea and viscoelastic material in-fused through a cannula placed intothe incision to separate the Desce-met membrane from the overlyingstromaltissue. After separation of theDescemet membrane, a trephine can

be used to cut a central groove intotherecipient corneal bed until a gushof viscoelastic material is seen. Theoverlying tissue can then be excisedusing corneal scissors withoutcausing damage to the Descemetmembrane.

Forlamellar keratoplastiesa full-

thickness button from a donor ca-daver is then cutwith a trephine, andthe endothelium is removed with amethylcellulose sponge. The donorbutton is then sutured to the recipi-ent corneal bed (Figure, E).After thedonor button has been sutured intoplace, the remaining viscoelastic ma-terial is irrigated out of the interfacewith a balanced salt solution in-fused through a 25-gauge cannula.

A

B

C

E

D

A, A trephine is used to make an 80%- to 90%-thick incision into the hosts cornea. B, A sharp, rounded blade is used carefully at the base of the groove to dissectthe deep stromal tissue parallel to the Descemet membrane. A 25-gauge cannula is inserted into this groove, and viscoelastic material (sodium hyaluronate[Healon]) is slowly injected. C, The viscoelastic material is forced between the corneal lamellae in a central direction, dissecting the Descemet membrane from theoverlying stroma. D, The cannula is advanced into the space between the stroma and detached Descemet membrane as viscoelastic material is injected tocomplete the dissection. E, The donor graft is sewn into the recipient corneal bed and the viscoelastic material irrigated from the interface between the donortissue and the patients Descemet membrane.




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For penetrating keratoplastiesthe same techniques are used. Fol-lowing resection of the diseasedstro-mal tissue from the Descemet mem-brane,iris-endothelial adhesions andother anterior segment abnormali-ties can be seen through the trans-parent Descemet membrane. Thesurgeon then carefully incises the

Descemet membrane and separatesadhesions from the underlying tis-sue, with direct visualization pre-venting the inadvertent incision ofunderlying anterior segment struc-tures. The Descemet membrane canthen be incised along the trephineincision, and a full-thickness do-nor button can be sutured to the re-cipient corneal bed.

REPORT OF CASES

CASE 1

A 48-year-old man with keratoco-nus had a best-corrected visual acu-ity of 20/30 OS because of keratoco-nus; a visual acuity of countingfingers at 2 ft OD was uncorrectablebecause of previous trauma. He wasunable to tolerate spectacle correc-tion because of distortion. His best-corrected visual acuity was 20/25OSwith a rigid, gas permeable contactlens, but he was intolerant ofthe lens.Deep lamellar keratoplasty as a tech-nique for optical restoration wasper-

formed to minimize the risk of graftrejection. Using an 8-mm suction tre-phine, a partial-thickness groove wasmade in the recipient corneal bed.The wound was separated in the 10-oclock position using Colibri for-ceps, and a rounded blade was thenused to make a deep incision that ranparallel to the stromal lamellae. Theincision began at the bottom of thetrephine incision, moving radially to-ward thecentral cornea, creating a 1-to 2-mm pocket. Theviscoelasticma-terial, sodium hyaluronate (Healon),

was slowly injected into this pocket.It was forced through the posteriorstromal lamellae along the path ofleast resistance, causing the Desce-met membrane to separate from theposterior stromal tissue. Corneal scis-sors were then used to separate thepatients corneal stromal tissue fromthe underlying Descemet mem-brane by cutting along the groovewith one blade between the stroma

and Descemet membrane. Centralstromaltissuewasliftedfrom theeye.The Descemet membrane remainedintact. An 8.25-mmfull-thicknessdo-nor button was cut with a trephine,and the endothelium was removedwith a methylcellulose sponge. Thedonor button was sutured to the re-cipient corneal bed. The remaining

viscoelastic material was then irri-gated from the interface with a bal-anced salt solution using a 25-gaugecannula. The postoperative coursewasuneventful, with complete clear-ing of the graft occurring within 2weeks. The interface between thegraft and Descemet membrane re-mained clear. The patient under-went selective suture removal 3months postoperatively. Uncor-rected visual acuity was 20/70 OS,and best spectacle-corrected visualacuity was 20/25 OS with 3.5 diop-

ters (D) of residual astigmatism.

CASE 2

A 63-year-old man had a best-corrected visualacuity of 20/400OD,attributable to corneal thinning andscarring from a previously treatedbacterial ulcer that extended ap-proximately 60% to 70% into theanterior corneal stroma withoutinvolvement of the Descemet mem-brane. Deep lamellar keratoplastywas performed for visual rehabili-

tation. Using a 7.5-mm suction tre-phine, the same technique used incase 1 was then employed to suc-cessfully dissect down to an intactDescemet membrane. A 7.75-mmfull-thickness donor button was su-tured to the recipient corneal bed.The postoperative course was un-eventful, with complete clearing ofthe graft occurring within 3 weeks.The junction between the graft andDescemet membrane remained clear.The patient underwent selective su-ture removal 3 months postopera-

tively and had an uncorrected vi-sual acuity of 20/70 OD and a bestspectacle-corrected visual acuity of20/30 OD with 2.5 D of residualastigmatism.

CASE 3

An 8-year-old boy sustained a force-ful blowto the right eye with a bluntobject 9 months prior to our exami-

nation. The trauma was compli-cated by total hyphema, glaucoma,and subsequent dense blood stain-ing of the entire cornea. Intraocularpressure could not be controlledwith topical medications, and heunderwent cyclocryotherapy on 2occasions. He was referred to us foradditional care that included pen-

etrating keratoplasty and surgery forglaucoma. Visual acuity was lightperception OD with good color dis-crimination and entopic phenom-enon.Findingsfrom ultrasound bio-microscopy indicated extensivedisruption of the anterior segmentwith anterior synechiae anddisplace-ment of the lens into the anteriorchamber.Because evidence of iris ad-herence to the endothelial surfacecould not be seen directly, deep la-mellar dissection was performed toremove blood-stained stroma,

thereby allowing visualization of theiris through the Descemet mem-brane prior to entering the anteriorchamber during penetrating kera-toplasty. Using an 8-mm trephine,a partial-thickness groove was madein the recipient corneal bed. Thewound was separated in the 10-oclock position using Colibri for-ceps, and a rounded blade was thenused to make a deep incision that ranparallel to the stromal lamellae. So-dium hyaluronate was slowly in-jected into this pocket. It was forced

through the posterior stromal lamel-lae along the path of least resis-tance, causing the Descemet mem-brane to separate from the posteriorstromal tissue. Corneal scissorswereused to separate blood-stained stro-mal tissue of the host by cuttingalong the groove with one blade be-tween the stroma and Descemetmembrane. Central stromal tissuewas lifted from the eye. The Desce-met membrane remained intact. Aretrocorneal inflammatory mem-brane could be seen clearly through

the Descemet membrane. The iristissue was adherent to the endothe-lial surface, and a preexisting rent inthe anterior lens capsule, attribut-ableto the patients previoustrauma,with release of cortical material intothe anterior chamber, could be seen.The Descemet membrane was care-fully incised in the 9-oclock posi-tion, and a potential space wasidentified between the Descemet




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membrane and underlying tissues.The Descemet membrane was gen-tly separated from these underly-ing tissues as it was incised along thetrephination wound. Using thesemaneuvers, no inadvertent inci-sions were made in the iris tissue asit was dissected from the endothe-lial surface. Cataract removal, pen-

etrating keratoplasty, and Ahmedvalve placement were completedwithout difficulty.

CASE 4

A 79-year-old man had previouslyundergone repair of a complicatedretinal detachment in the right eyeusing vitrectomy and silicone oiltamponade. He was left aphakic andeventually developed corneal de-compensation, attributable to sili-cone oil toxicity. He was referred to

us for penetrating keratoplasty alongwith silicone oil removal from thevitreous cavity to provide better vi-sualization of the posterior seg-ment and for possible visual reha-bilitation. Prior to surgery, it wasknown that the iris was adherent tothe posterior surface of the corneain several areas, although anteriorsegment structures could not be seenat the time of surgery because of cor-neal clouding. A stab incision wasmade into the cornea at the limbusin the 9-oclock position, and vis-

coelastic material (Healon) wasinstilled through deep corneal la-mellae to separate the Descemetmembrane from overlying stromaltissue over theentire area of thecor-nea. An 8-mm trephine was thenused to cut a central groove into therecipient corneal bed. A gush of vis-coelastic material (Healon) indi-cated that the lamellar dissectionplane had been reached. The stro-m al t i ssue w as ex ci sed usi ngcorneal scissors along the trephina-tion groove. The Descemet mem-

brane remained intact. It was thenpossible to see anterior segmentstructures through the Descemetmembrane. Several areas of ante-rior synechiae were present. TheDescemet membrane was incisedwith a supersharp blade in an areawithout iris adhesions, and the in-cision was continued along thetrephination wound using cornealscissors. During this process the iris

was separated from the Descemetmembrane ahead of the scissors byblunt dissection using a cyclodialy-sis spatula. Following these maneu-vers the anterior chamber was re-formed. Silicone oil removal andpenetrating keratoplasty were com-pleted without complications.

COMMENT

Detachment of the Descemet mem-brane following inadvertent injec-tion of viscoelastic material ante-rior to the membrane has beendescribed during intraocular sur-gery.18-21 These detachments havebeen successfully repaired using avariety of techniques includingplacementof sulfur hexafluoride gas(SF6), 22 air,23 viscoelastic sub-stances,24 and perfluoropropane gas(C3F8)25 into the anterior cham-

ber. Spontaneous reattachment canalso occur.23 Based on these obser-vations, we postulated that we couldcreate a controlled separation of theDescemet membrane from overly-ing stromal tissue using viscoelas-tic material to facilitate deep lamel-lar dissection.

One of the reasons why tradi-tional lamellar keratoplasty mayyield a suboptimal visual result isthat withcurrent technologies, someof the stroma left behind during thelamellar dissection becomes opaque

or contains residual diseased tis-sue. A variety of surgical tech-niqueshave been developedover theyears to facilitatedeep lamellar kera-toplasty and improve optical out-comes. Deep lamellar dissectionwithintrastromal air was originally de-scribed by Archila.1 Using this tech-nique, he was able to perform deeplamellar dissectionsuccessfullyin 10eyes with no inadvertent entry intothe anterior chamber. In anotherstudy,9 deeplamellar dissection withintrastromal air was attempted in 10

eyes. Air dissection was performedsuccessfully in 6 of 10 eyes in thatstudy. Conversion to full-thicknesspenetrating keratoplasty was re-quired in4 of10 eyes because ofin-advertent perforation into the Des-cemet membrane at the time ofsurgery. In only 1 of 6 eyes that un-derwent successful air dissectionwasthe separation at the Descemet mem-brane.

Deeplamellar keratoplasties us-ing Barraquer microkeratomes havealso been attempted by several au-thors, with mixed results.10,11 Thereare a number of technical difficul-ties in performing microkeratome-assisted lamellar keratoplasty. In ad-dition, the procedure results in onlya partial-thickness dissection, leav-

ing residual corneal stroma downto the Descemet membrane; thisresidual stromal tissue may opacify,necessitating eventual performanceof a full-thickness penetrating kera-toplasty.

Deeplamellar keratoplasties us-ing hydrodelineation have also beenattempted with some success.16 Us-ing this technique, saline solution isinjected through a partial-thick-ness lamellar incision using a blunt27-gauge cannula. The saline pen-etrates the stromal collagen fibers,

causing them to whiten and swell.This in turn makes tissue removalusing blunt dissection easier to per-form. Using this technique, Sugitaand Kondo16 performed deeplamel-lar keratoplasty on 120 eyes withcorneal stromal opacification. Theywere able to successfully dissectdown to the Descemet membrane in75% of eyes using this technique.However, they also reported a 39.2%rate of puncture of the Descemetmembrane in this series of eyes. Theauthors stated that none of the eyes

with punctures in the Descemetmembrane required conversion topenetrating keratoplasty, and allhad similar outcomes to eyeswithout puncture 6 months post-operatively.

Full-thickness keratoplasty us-ing viscodelamination has been pre-viously described in the treatment ofpainful bullous keratopathy.17 Sunand coauthors17 used this tech-nique to facilitate dissection of cor-neal tissuein 21 eyes in patientswithpainful bullous keratopathy. Using

this technique, Sun et al success-fully dissected the diseased edema-tous corneal tissue in all of the eyeswith no cases of inadvertent pen-etration of the Descemet mem-brane. They did not dissect all theway down to the Descemet mem-brane but attempted to remove asmuch of the edematous corneal tis-sue as possible. Six months postop-eratively, the painfulsymptoms were




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relieved in all of the cases, and amodest improvement in vision wasachieved in 73% of the eyes. How-ever, since the underlying cause ofthe bullous keratopathy is pre-sumed to be a poorly or nonfunc-tioning endothelial pumpingmecha-nism, one would assume that thedonor lamellar graft would eventu-

ally become edematous as well.All 4 patients in our study hadsuccessful surgical outcomes; spe-cifically, there were no cases of in-advertent puncture of the Descemetmembrane during theviscoelasticdis-section. In the2 patients whounder-went lamellar keratoplasty, thedonor grafts remained clear postop-eratively with no evidence of inter-face opacification, host endothelialdecompensation, pseudoanteriorchamber formation, or complica-tions from retained viscoelastic sub-

stance. In the 2 patients who under-went penetrating keratoplasty, theiris-endothelial adhesions, inflam-matory membranes, and disruptedanterior segment structuresweresuc-cessfully visualized prior to incisionof the Descemet membrane, allow-ing us to avoid inadvertent surgicaltrauma to normal tissues.

Thesurgical techniquewe havedescribed offers all of the advan-tages of traditional lamellar kerato-plasty with the added advantage ofleaving a clear interface. It shoulden-

able surgeons to remove all of thestroma from the underlying Desce-met membrane safely and reliably,therebyeliminating the potential dis-advantage of leaving residual tissuethat could compromise vision. Thistechnique has the advantage over theother full-thickness techniques, in-cluding air dissection and hydrode-lamination, in that there is a low riskof inadvertent puncture of the Des-cemet membrane, and it is techni-cally easy to perform. The simplifi-cationof the techniqueshouldallow

surgeons to offer lamellar kerato-plasty to those patients who havetheir disease process confined to thestroma with normal endothelium.The technique is also a useful meansfor seeing anterior segment struc-tures prior to incising the Desce-met membrane in patients with sus-pected iridocorneal adhesions or

other disruption of normal ante-rior segment architecture. By visu-alizing the tissue, inadvertent inci-sion of the iris can be avoided.

Accepted for publication July16, 1999.This study was supported in part

by Research to Prevent Blindness, Inc,New York, NY. Dr Maloney is the re-cipient of a Research to PreventBlind-ness, Inc, Career Development Award,and Dr Holland is the recipient of aResearch to Prevent Blindness, Inc,Lew R. Wasserman Merit Award.

Corresponding author: EdwardE. Manche, MD, Stanford UniversitySchool of Medicine, Department ofOphthalmology, 300PasteurDr, RoomA157, Stanford, CA 94305-5308(e-mail: [email protected]).

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Deep Lamellar Keratoplasty