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Transforming growth factor-beta expression in rat eyes with mechanical debridement of corneal epithelium or epithelial flap.

Lee JJ, Kim MK, Shin KS, Shin MS, Wee WR, Lee JH

Department of Ophthalmology, Seoul National University College of Medicine, #28 Yongon-dong, Chongno-gu, Seoul, Republic of Korea.

PURPOSE: To compare corneal haze and transforming growth factor (TGF)-beta expression in rat eyes with mechanical debridement of corneal epithelium or a chemically induced epithelial flap. SETTING: Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea. METHODS: Sixty corneas from 60 Sprague-Dawley rats were treated in 1 of 4 ways using a 2.0 mm trephine: corneal epithelium mechanically removed (Group 1), central cornea exposed to 20% ethanol for 30 seconds (Group 2), corneal epithelial flap made by applying 20% ethanol for 30 seconds and flap amputated (Group 3), corneal epithelial flap repositioned after ethanol-assisted detachment of epithelium as in Group 3 (Group 4). Corneal haze was graded. The TGF-beta expression was measured in corneas and lacrimal glands using reverse transcription polymerase chain reaction and immunohistochemistry until day 30. Semiquantitative analysis was done in a density ratio of TGF-beta/beta-actin with image analyzer and densitometry. RESULTS: Corneal haze was more severe in Groups 1 and 3 than in Groups 2 and 4. By day 7, mRNA expression of TGF-beta2 and type II receptor in corneas had increased more in Groups 1 and 3 than in Groups 2 and 4. In lacrimal glands, only TGF-beta1 in Group 3 increased until day 7. In corneas, staining of both TGF-beta1 and beta2 increased, more prominently in Groups 1 and 3. Lacrimal gland staining was more intense in Groups 1 and 3. CONCLUSION: Well-positioned corneal epithelial flaps may decrease corneal haze by reducing expression of TGF-beta; inadvertent removal of an epithelial flap made by ethanol seems to exacerbate haze by increasing TGF-beta.

Published 25 March 2008 in J Cataract Refract Surg, 34(4): 662-9.
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