K Barton1, D L Budenz, P T Khaw, S C Tseng. 1. Bascom Palmer Eye Institute, University of Miami School of Medicine, Florida, USA. keith1barton@cs.com
Abstract
PURPOSE: To investigate the potential use of amniotic membrane transplantation (AMT) in the construction of glaucoma filtering blebs. METHODS: Twenty-four albino rabbits underwent glaucoma filtration surgery in one eye. In alternate cases, the conjunctival flap was replaced with AMT. Postoperative examination data were grouped into three time points. Six animals with AMT and six filtration surgery-controls were euthanatized at each of two postoperative time points, and tissue was obtained for histologic examination. Conjunctival biopsies were explanted for estimation of fibroblast outgrowth. RESULTS: Bleb formation was observed in all eyes, and amniotic membranes were epithelialized after 11.2 +/- 2.48 (mean +/- SD) days. Throughout the study IOPs were significantly lower in operated than unoperated fellow eyes. Between postoperative days 11 and 16 (the middle time point), the percentage IOP reduction in AMT eyes was significantly greater than in filtration surgery controls (P = 0.014), though not at other time points. Filtration surgery survival was significantly longer in the AMT group (22.3 +/- 3.8 days; mean +/- SE) than in "No AMT" controls (14.0 +/- 1.6 days; P = 0.035). In tissue culture, significantly less fibroblast outgrowth occurred from AMT explants when compared with unoperated conjunctiva (P = 0.01) between postoperative days 3 and 9 (the early time point). Amniotic membrane transplants were intact on histologic examination after 14 days but were associated with considerable granulomatous inflammation. After 36 days, the ocular surfaces remained clinically intact, but lysis of AMT was noted histologically. CONCLUSIONS: AMT exhibits potential as an alternative tissue to conjunctiva in the construction of glaucoma filtration blebs. The healing response as demonstrated by fibroblast outgrowth is retarded when compared with conventional conjunctival closure. The improvement in bleb survival must be weighed against the potential for complications related to delayed healing. In rabbits, human amniotic membrane elicited a late xenograft reaction, leading to granulomatous inflammation and dissolution of the membrane.
PURPOSE: To investigate the potential use of amniotic membrane transplantation (AMT) in the construction of glaucoma filtering blebs. METHODS: Twenty-four albino rabbits underwent glaucoma filtration surgery in one eye. In alternate cases, the conjunctival flap was replaced with AMT. Postoperative examination data were grouped into three time points. Six animals with AMT and six filtration surgery-controls were euthanatized at each of two postoperative time points, and tissue was obtained for histologic examination. Conjunctival biopsies were explanted for estimation of fibroblast outgrowth. RESULTS: Bleb formation was observed in all eyes, and amniotic membranes were epithelialized after 11.2 +/- 2.48 (mean +/- SD) days. Throughout the study IOPs were significantly lower in operated than unoperated fellow eyes. Between postoperative days 11 and 16 (the middle time point), the percentage IOP reduction in AMT eyes was significantly greater than in filtration surgery controls (P = 0.014), though not at other time points. Filtration surgery survival was significantly longer in the AMT group (22.3 +/- 3.8 days; mean +/- SE) than in "No AMT" controls (14.0 +/- 1.6 days; P = 0.035). In tissue culture, significantly less fibroblast outgrowth occurred from AMT explants when compared with unoperated conjunctiva (P = 0.01) between postoperative days 3 and 9 (the early time point). Amniotic membrane transplants were intact on histologic examination after 14 days but were associated with considerable granulomatous inflammation. After 36 days, the ocular surfaces remained clinically intact, but lysis of AMT was noted histologically. CONCLUSIONS:AMT exhibits potential as an alternative tissue to conjunctiva in the construction of glaucoma filtration blebs. The healing response as demonstrated by fibroblast outgrowth is retarded when compared with conventional conjunctival closure. The improvement in bleb survival must be weighed against the potential for complications related to delayed healing. In rabbits, human amniotic membrane elicited a late xenograft reaction, leading to granulomatous inflammation and dissolution of the membrane.