135

THE CORNEAL GRAFTBy B. W. RYCROFT, O.B.E., M.D., D.O.M.S., F.R.C.S.(ENG.).

From the Corneo-Plastic Unit and Regional Eye Bank, Queen Victoria Hospital, East Grinstead, Sussex

The idea of treating corneal blindness by tre-phine surgery first appears in English literature in1796:

'After ulcerf of the cornea, which have beenlarge, the inequalitief and opacity of the cicatrixobfcures the fight; in thif cafe could not a fmallpiece of the cornea be cut out by a kind of trephineabout the fize of a thick briftle, or a small crow-quill and would it not heal with a tranfparentfcar?'

Erasmus Darwin,Zoonomia, Pt. II, p. 48, I796.

Other notions about this time were those ofPellier de Quengsy who suggested the insertion ofa crystal into the opacity of a corneal scar, ofChevalier Taylor whose advice was either to ' pareoff the excressence ' or to rub it hard with a brushof barley awns. Meade (1775) preferred a powderof equal parts'of glass and sugar, doubtless to beapplied with the same vigour.

Abortive trials and unsuccessful experimentscharacterized the I9th century, but sufficientstimulus to surgical effort was provided by thecorneal blindness of small-pox and trachoma,which had been spread far and wide throughoutEurope by travelling armies. Conteriporary ex-periments were mainly concerned with cross-grafting of animals; human experiments were rareand what there were usually failed from infection,poor tools and no anaesthesia. By the end of thecentury, however, ophthalmology had become aseparate specialty and the golden era of eyesurgery began. The influence of Pasteur andLister began to control infection and,general andlocal anaesthesia came into use, allowing accuracyof technique in eye operations to supersede speedof accomplishment.The patient work of von Hippel' over ten years

laid the foundation of modern corneal graft sur-gery; he showed a case at Heidelberg in i886 and1887 where a rabbit graft had improved the sightof a young girl. In I905 came the famous limeburn case of Zirm2, in which improved vision was

recorded for two years after operation. A child'scornea provided the graft which was held in placeby overlay stitches; this represented a definiteadvance in the technique of fixing the graft.By the beginning of the 2oth ce itu y the sur-

gical principles of corneal grafting had b !en estab-lished and these hold good today. They includethe exclusive use of a human graft cut by trephine,safe anaesthesia and strict asepsis, minimumtrauma of the graft together with secure fixation.The rest of the century to date has been occupiedwith refinements of technique and more matureselection of cases. Future problems which remainto be solved are the best methods of prolongedgraft preservation and a correct appreciation of theimmunological reactions which are set in motionwhen a corneal graft is transplanted.Functions of a Corneal GraftA corneal graft may serve three purposes,

namely:i. Optical, which is performed for the improve-

ment of vision and consists of the removal of anopaque disc of corneal scar tissue and replacementby a similar transparent disc from another cornea.

2. Therapeutic, in which a graft is applied tohasten the healing of chronic corneal ulcers andto relieve severe pain. This method is employedon the same principle as a cross leg flap is used tocure varicose ulceration. Such a graft is used alsoto reinforce deficiencies in the wall of the eyeballwhich have resulted from old perforations.

3. Cosmetic, when it is desired to remove ahideous white scar on a blind eye. This type ofgraft is often combined with tattoo.

Corneal grafts are of three types: (a) Fullthickness, in which the whole thickness of thecornea is used and the globe is opened; this typeof graft is comparable to the Wolfe skin graftand is effective for deep corneal scars. Thediameter of full thickness grafts is 5 to 6 mm.(b) Partial thickness, in which a layer of the corneais split off and replaced by a wafer graft of partialcorneal thickness. Although a safe procedure it isonly applicable to superficial corneal scars or for

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136 POSTGRADUATE MEDICAL JOURNAL March 1955

(a) (b) (A

FIG. I.-(a) Full-thickness graft; (b) partial-thickness graft; (c) flange graft.

therapeutic pruposes. These grafts may be from5 to Io mm. in diameter. (c) Flange, which is acombination of a partial and a full thickness graft.This type has the merit of greater safety by formingan overlap joint but is more difficult to cut. Fig.I.

The OperationAbsence of infection by repeated conjunctival

cultures is established before operation in the hostand donor eye. Anaesthesia is generally by regionalorbital block, using i per cent. xylocain with 5 toio per cent. alcohol together with surface an-aesthesia of 4 per cent. cocaine with adrenalin.The facial nerve is blocked as it emerges from thestylomastoid foramen in order to prevent in-advertent forcible closure of the lids by the patient;this would expel the contents of the eye when theglobe was opened.A 5-mm. graft is next cut by trephine from a

donor eye; the graft must have clean edges, freefrom tags, and this is best obtained by punching thegraft. A bed of the same size is then drilled in thereceiving eye and the graft is placed in it. Thegraft is held in place either by minute direct edgeto edge sutures around the periphery or by overlaysutures which cross the graft. Fig. 2.

Both eyes are bandaged for a week and at theend of that period the graft has healed in position,but final clarity is not established until the thirdweek when the graft begins to live on the host.Fig. 3.Complications

Immediate. (i) The graft may fit badly owingto corneal distortion when the eye is opened, andthe wound will leak; this is bound to lead to anopaque graft as a water-tight joint between hostand donor is absolutely essential for success.Hence at least two donor corneas must be availableto provide alternate size grafts. (2) Infection is nolonger a menace and is adequately controlled byantibiotics. If the donor cornea comes from acadaver special care is needed to ensure sterility as

B. coli, streptococci and haemolytic staphylococcihave been found in post-mortem eyes. (3) De-fects of technique should not arise and instrumentsand needles must have perfect edges and points;they are scrutinized by slit lamp microscopy beforeoperation.

Late. (I) Secondary glaucoma may be a prob-lem owing to adhesion of the iris to the graft;this is a sequel of a leaking section which causesnon reformation of the anterior chamber. (2)Opacification of the graft from the immunologicalreactions of oedema and vascularization are un-predictable. Fortunately cortisone, by local dropsor subconjunctival injections, is of some value incontrolling neo-vascularization and pre- and post-operative B-radiation to the cornea helps toprevent vascularization.

The DonorI. The sources. When corneal graft operations

were few in number sufficient donor material couldusually be obtained from eyes which had to beexcised for sarcoma of the choroid or injury and,indeed, this remains an important, though in-adequate, source today. The main source, how-ever, must now be the cadaver. Such donoreyes or corneas should be removed within tenhours of death under aseptic conditions and arebest obtained from aged adults who have died anatural death. Another source of great potentialvalue is the bequest eye. Since I953, by virtue ofthe Corneal Grafting Act, it has been legal for aperson to bequeath his or her eyes simply by ex-pressing such a wish verbally or in writing. Afterdeath the nearest relative or doctor informs thelocal Eye Bank or hospital where corneal graftingis carried out and the hospital then makes arrange-ments to obtain the eyes. At East Grinstead thissource is of great value and arrangements workwell; a team is always on call and a set of sterileenucleation instruments always ready. Relativestreat the procedure of carrying out the deceased'swishes with dignity and co-operation.

2. Preservation. Whilst a fresh, living graft is

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MarchIg955 RYCROFT: The Corneal Graft I37

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FIG. 2.-General View of Corneal Graft Operation. (Left Eye:5 mm. penetrating circular graft.) The Franceschetti trephineis being applied to mark the site of the graft. Retraction stitchesare placed above, in the superior rectus muscle sheath and below,in the lower lid so that external pressure on the globe by aspeculum is avoided. This is an important point of techniquein penetrating graft cases.

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the best material for transplantation this isobviously a counsel of perfection which can rarelybe realized; methods of preserving graft materialhave, therefore, to be used. At present, immersionin an antibiotic-liquid paraffin emulsion at 4° C.in which they are suitable for use up to 14 days, orin water vapour at 4° C. for three days, are twopopular methods. Recently Polge, Parkes andSmith3 have shown that it is possible to preservegonad tissue over long periods by impregnatingthe tissue with glycerol and freezing it rapidly to-79° C.; after thawing out the gland tissue func-tions again. Attention has been drawn to thepossibility of preserving corneal tissue hv this

means by Eastcott and his colleagues.4 So farresults have not yet proved entirely satisfactorybut research continues, for, if this method proves tobe successful, the banking and storage of cornealgraft material will be greatly facilitated and wastagewill be eliminated. The orderly admission ofpatients waiting for corneal grafts will also be moreconveniently arranged.PathologyWhen a graft from one individual is transplanted

to an individual of the same species it is called ahomograft; homografts always die as a result ofimmunological reaction at varying periods after

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138 POSTGRADUATE MEDICAL JOURNAL March 1955

transplantation with the possible exception ofgland tissue, cartilage and cornea.

Just why the cornea behaves differently fromother grafts is not clearly understood. It may bebecause a corneal graft has few cells and is small;the antigen stimulus, therefore, is low, or it maybe because of absence of blood vessels. It is, how-ever, quite certain (Billingham5) that cornealtissue per se is capable of creating an immuno-logical reaction. Then again, the graft may actsimply as a scaffold after the initial cells have died;the cells may be replaced by migration from thehost. It is possible that this is a more likely viewrather than the cornea should be endowed with thespecial properties of a true graft. The invasion ofthe blood vecssels as a result of reaction is the signalfor physiological failure and opacification; nooptical graft is likely to succeed where deep cornealblood vessels are present. Blood groups of hostand donor have no apparent significance.Criteria of Selection and PrognosisThese criteria concern the local eye conditions,

the condition of the donor graft and the initialdisease which caused the corneal scar.

The host eye. Local condition. The eye must bewhite and free from infection or vascularization ifan optical graft is to be used. There must be noincrease of intraocular pressure and retinal func-tion must be normal. It cannot be too stronglyurged that a corneal graft will only restore sightwhere blindness is due to a corneal scar and wherethe posterior structures of the eye are normal, i.e.free from retinal degeneration, detachment orglaucoma. Cataracts may be successfully removedafter grafting. The scar which is to be removedshould not occupy the entire cornea but a rim ofnormal corneal tissue should be present.The donor graft must be as fresh as possible

with good lustre, transparency and a clean-cutedge. Loss of surface epithelium is of no con-sequence but the stroma and membranes must notbe separated. The graft must have been provedto be sterile at all stages of preservation.

Initial disease. The diseases which cause blind-ness from corneal scars and which may be treatedby grafting are grouped for prognosis as follows:

I. Thin scars of corneal ulcers.2. Conical cornea.

Favourable 3. Corneal dystrophies.(about 70 per cent. 4. Certain corneal degeneration.clear grafts). 5. Mild interstitial keratitis.

6. Neuropathic scars.

i. Dense scars of corneal ulcers.Fair 2. Non-specific and severe inter-

(about 40 per cent. stitial keratitis.clear grafts). 3. Moderate burns and ex-

plosion injuries.

I. Severe burns anld splash ill-Bad juries.

(less than io per 2. Pemphigus.cent. clear grafts). 3. Dense scars of corneal per-

foration with adherent iris.

ResultsA clear graft is considered by some surgeons to

be a success but it does not always mean improve-ment of vision; sometimes there may be undetect-able amblyopia or macular degeneration whichspoils the result of surgery. But in general, andcertainly for the patient, the improvement of visionis the standard of success.

In the favourable group at least 70 per cent. ofcases will have restored vision to varying degrees.In the middle group about 40 per cent. will haveimproved vision but in the unfavourable groupthere will be few. Yet it must be rememberedthat even in this group a slight improvement suchas will enable perception of large objects givessome measure of independence which is ofinestimable value.The latest published results of a larger series in

detail are those of Townley Paton6 which cover 299transplantations followed up for two months orlonger.Transparent Grafts (anatomical assessment)Of these 64.5 per cent. had clear grafts which

are differentiated as follows:

Cleargrafts No. of

Per cent. graftsConical cornea .. .. 89.3 84Groenouw's dystrophy .. .. 85.7 28Non-specific scars .. .. 68.8 I6Inactive ulcers ... .. 66.7 20Interstitial keratitis .. .. 62.2 45Leukoma .. .. .. .. 55.6 IActive ulcer .. . 50 6Trachoma .. .... .. 45.5 IBurns, explosions and wounds .. 39. 23Adherent leukoma . . 35.3 17Fuch's dystrophy... .. .. 30 13

Visual Improvement (physiological assessment)So far as vision is concerned Paton analyzes

222 grafts as follows:

Cases72.1 per cent. showed improvement .. .. i6020.7 per cent. remain with the same vision .. 465.9 per cent. had reduced vision .... 13

In corneal grafting the words of de Wecker7must always be borne in mind: ' We have noright in these cases to refuse the slightest aid tosufferers who have but this one remaining chanceto recover a little sight.'

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March 1955 RYCROFT: The Corneal Graft 39

Future ProblemsThree main problems remain to be solved. In-

fection is no longer a menace, principles of tech-nique have been generally established and theselection of cases has been clarified by increasedexperience.

But the problem of vascularization and oedemacausing early or late opacification of the graft isstill unsolved; the solution will more likely befound in the laboratory than in the operatingtheatre.

Closely associated is the best method of storingdonor material for on this depends the whole futureof the organization and expansion of corneal graftsurgery.

Mr. Gordon Clemetson of the Photographic

Unit, Queen Victoria Hospital, East Grinstead,has kindly provided the photographs.Acknowledgments

Figs. I and 3, reproduced by kind permissionof Messrs. Butterworth, and Fig. 2 by kindpermission of The Medical Press.

REFERENCESI. v. HIPPEL (I888), Gf. Arch., 34, Io8.2. ZIRM, E. (1905), Arch. Ophth., 64, 5o0.3. POLGE, G., PARKES, A. S., and SMITH, A. U. (1949),

Nature, Lond., 164, 666.4. EASTCOTT, H. H. G., et al. (1954), Lancet, Jan. 30, 6805.5. BILLINGHAM, R. E. (I953), 'Preservation and Transplanta-

tion of normal tissues' (Ciba Foundation), p. 218.6. TOWNLEY PATON, R. (1953), Trans. Amer. Ophth. Society,

51.7. DE WECKER (1879), ' Ocular Therapeutics,' London, p. I45..

HOW TO GET THEREAn Address Book for the Medical profession, showing how to reach thevarious Colleges, Societies, Institutes and Hospitals in or near London

New (Fourth) Edition: 1954 Price 2s. 6d. (2s. 9d., post free)

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FELLOWSHIP OF POSTGRADUATE MEDICINE60 Portland Place, London, W.I

Bibliographv continued from page 12--Keith Ball, M.D., M.R.C.P.BIBLIOGRAPHY

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