Experimental Research with Corneal Heterografts

Abstract

Laboratory oftheOphthalmological Clinic, University ofGeneva (Director: Prof. A.Franceschetti) KERATOPLASTY still poses problems, andthemoreweextend ourexperiments totrytoelucidate thebiology ofthetissue fragments incorporated into the cornea, themorethebiology appears complex. Until now,ithasbeen almost dogma, because ofthefailure ofmostprevious attempts, tostate thatcorneal heterografts arenotpossible; thatfirst theybecomeopaque, andthentheyarereplaced byreactive tissue originating inthereceiver. A fewworkers havesucceeded inmaintaining fragments ofclear transplanted cornea inthecornea ofanother species, butthese experiments havenot beenveryextensive (Bonnefon, 1914; Galante, 1938), andsimilar workdone since hasgiven negative results (Thomas, 1936; Castroviejo, 1937). Though this question seemed tobefinally closed, webegan further experiments after receiving apersonal communication fromDr.Bock, nowacollaborator of Professor MaumeneeinSanFrancisco. Bock, while trying toexplain the mechanism ofopacification ofcorneal grafts, proposed a technique of implantation whichdiffers fromthatofperforation andlamellar grafts. Theformer isfollowed all toooften intherabbit byinfection orinclosure of theiris; withthelatter itisdifficult toachieve fixation. Technique Thenewmethod+ consists inusing aspatula withthin edges tocutthecorneal stroma ofthereceiver starting froma limbal incisioni, andtoslide intotheslit somadea rounded edgeofthecorneatobegrafted. Thusthegraft isincluded between lamellae ofthecorneal stromaoftherecipient, whichobviously implies totally different biological conditions fromthose obtaining withtheusual types ofgraft; i.e., those which arein contact withthesurface, andalso, inthecaseofperforating grafts, withtheaqueous humour. Thistechnique, whichissimple toperform, hasgiven usinthepast6monthssome unexpected results which poseawholeseries ofnewbiological problems.