| Objective: To investigate the effect of UV-B irradiation on corneal tissue with the corneal flap presence or loss after Lasik ,and evaluate the corneal flap function. Methods: Thirty-six adult New Zealand White rabbits were divided randomly into 6 groups,the flap-retained UV-B irradiated group( â… a group). the flap-lost UV-B irradiated group (â… b group) .group receving irradiation alone (â… c group). the nonirradiated flap-retained group (â…¡ a group). the nonirradiated flap-lost group(â…¡b group) and untreaded group(â…¡c group). Twenty-four rabbits of â… a group, â… b group, â…¡ a group and â…¡ b group were operated to making corneal flap on the Lasik operational pattern, â… c group and â…¡ c group served as control. After corneal flap were created , them of â… b group and â…¡ b group were cut purposely. One week after operation, rabbits of â… a group, â… b group and â… c group rabbits of were exposed to 100 mJ/cm2 UV-B (280-320 nm). Subepithelial haze was evaluated after operation and UV-B irradiation. Corneal morphology was assessed 2 and 4 weeks after UV-B exposure, employing light microscopic and transmission electron-microscopic techniques (TEM).Results: â… a group, â… c group,â…¡a group, and â…¡c group showed no haze and were histologically normal at all time intervals. The central parts of corneas were transparent after operation by slitlamp examination for the entire study period. Light microscopy revealed the epithelium had no apparent changes in the central parts of corneas. Space existed between the flap and the anterior stroma in the early stag(1 week to 5 weeks after operation) . The number of fibroblasts in the anterior stroma increased for a short time (5 weeks after operation). Through transmission electron microscopy examination, basement membrane of corneal epithelium was continuous. The density of hemidesmosomes was normal. The collagen fibrils were... |
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