Amniotic membrane grafts in ocular surface disease

Introduction:Amniotic membrane's unique combination of properties including the facilitation of migration of epithelial cells, the reinforcement of ba sal cellular adhesion and the encouragement of epithelial differentiation [ 6] together with its ability to modulate stromal scarring. and its anti-inf lammatory and anti-bacterial activity has led to its use in the treatment o f ocular surface pathology as well as an adjunct to stem cell grafts of the corneal limbus [6-4]. We report a prospective study of 30 patients. so tre ated. Material and methods: We studied 31 eyes of 30 patients subjected to amniot ic membrane grafts between September 1999 and May 2000. There were 25 men a nd 5 women with an average age of 60.1 (range 25-86) years who were followe d for a mean of 7.7 (range 4-11) months. 5 groups (A to D) were observed: A: 6 eyes. Small chronic ulcers without limbal involvement. B: 4 eyes. Ulcers of at least 75% corneal area or occupying 75% of the limb us. C: 9 eyes. Corneal burns. D: 8 eyes. Painful bullous corneal dystrophies unresponsive to other treatm ent. E: 4 eyes. Symblepharons. Amniotic membrane was placed on the corneal lesion, epithelial surface exte rnally [6, 15], trimmed and sutured with interrupted 10/0 nylon, removed at one month. In two patients (11, 12) inflamed conjunctiva was recessed and amnion sutured to the recessed margin. For the bullous dystrophies we remov ed all the corneal epithelium and either sutured the amnion to peri-limbal conjunctiva (4 eyes) or to the limbus (4 eyes). For the symblepharons the c onjunctiva was dissected to reform the fornix which was lined with amniotic membrane, sutured With 8/0 vicryl. Patients were reviewed regularity. Results: Group A: All heated within 15 days, in most with dissolution of th e amnion over 2-3 months although some persisted, covered with corneal epit helium. An eye with a Descemetocoele and one with a Microperforation both h ealed. Vision improved more than two in 4 of 6 eyes. Group B: 2 of 4 eyes healed, one despite detachment of the membrane after 1 5 days. One eye was salvaged by tarsorrhaphy over afresh keratoplasty after perforation of a neuroparalytic ulcer on failure of three successive amnio n grafts. The final cornea vascularised despite an amnion graft for a meta- herpetic ulcer. Group C: 2 of 9 eyes had limbal damage in one quadrant but 7 had vessels in at least three-quarters of the circumference, One (15) also had a limbal a utograft. 3 of 9 eyes healed satisfactorily with more than 2/10 improvement in acuity in each case. 2 showed further neovascularisation. despite surfa ce healing. One old chemical burn heated satisfactorily but vascularisation remained. 5 eyes failed to heal with lysis of the graft, the patient who h ad a limbal autograft developed a vascular pannus, and in 4 eyes neovascula risation progressed to cover the entire cornea. Group D: 3 eyes settled with loss of symptoms but in 5 the graft detached w ithin 15 days. All eyes where the membrane had been sutured to the conjunct iva beyond the limbus failed whilst 3 of 4 in which it had been sutured ant erior to the limbus succeeded, leaving a persistent whitish membrane under the epithelium. Group E: We were able to reconstruct the cul de sac in 3 out of 4 eyes. In one patient with recurrent pterygium good ocular movement was restored, pre viously limited by scarring. One with associated ocular surface damage from a thermal burn failed by scarring of the cul de sac a month after surgery. Discussion: Our best results were in persistent trophic ulcers of the corne a (Groups A and B) with a success rate of 80%, comparable to those of other s [49, 37, 38]. The ready availability of amniotic membrane in our facility makes amniotic membrane transplantation the main secondary treatment for s uch lesions, especially because of the visual improvement we obtained. Beca use we did not observe any improvement in corneal thickness after this trea tment we advise its early use before significant stromal lysis. The technique was not sufficient to control the effect of corneal anaesthes ia in two eyes [40] or in chemical burns suggesting that amniotic membrane alone is insufficient to promote corneal healing in the absence of limbal s tem cells. Nevertheless, three eyes did benefit. it has been suggested [13] that the anti-apoptotic function of amnion may prevent stem cell loss in s uch eyes [42], thus it appears logical to offer an amniotic membrane graft first, before stem cell transplantation, which may entrain complications in the donor eye if autografted [43] or because of the rejection risk of an a llograft. It may be that an amniotic membrane graft simply becomes a holdin g procedure allowing time to settle the eye so as to allow secondary proced ures to address the underlying cause of further damage. Our treatment of bullous dystrophy only succeeded on confining the graft to within the limbus, 3 out of 4 eyes becoming comfortable. By contrast we fo und amniotic membrane helpful in reconstructing symblepharons in the absenc e of local inflammation. Conclusion: Amniotic membrane grafting is a simple and straightforward surg ical technique which should form part of the therapeutic arsenal for the tr eatment of ocular surface disease. Indications for the technique need furth er clarification for it is evident that it cannot correct all secondary pat hology associated with limbal destruction. It is certainly preferable to co njunctival advancement and has proved useful in the re-construction of the cul-de-sac.