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J.C. Erie, J.W. McLaren, C.B. Nau, D.O. Hodge, W.M. Bourne; Reinnervation in the Cornea After PRK . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2680.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the reinnervation of human central corneas after PRK by sequential quantitative measurements of nerves viewed by confocal microscopy. Methods: Twenty-four eyes were studied in 14 patients who underwent PRK (VISX Star) to treat myopia from -1.25 to -5.75 D. The epithelium was removed by laser-scrape technique. Central corneas were scanned throughout their full-thickness by confocal microscopy before, and 1, 3, 6, 12, 24, and 36 months after PRK. Subbasal nerve fiber bundles appeared as bright, well-defined linear structures that were sometimes branched and often appeared in consecutive frames. The total nerve length of the subbasal nerve fiber bundles within each confocal frame (i.e. frame size, 0.475 x 0.350 mm) was measured by using custom software. All visible subbasal nerves and their branches were measured in 3 to 6 scans per eye per visit. Subbasal nerve densities at all visits after PRK were compared (paired t-test, Bonferroni-adjusted for multiple comparisons) with densities before PRK. Results: In the subbasal region, the density of the nerve fiber bundles was decreased 98%, 87%, 75%, and 60% at 1, 3, 6, and 12 months after PRK compared with preoperative (P<0.001). By 24 months after PRK the subbasal nerve fiber bundle density (6,232 ± 1,761 µm/mm2) was not significantly different from preoperative values (6,944 ± 1,935 µm/mm2, P=1.0) and remained unchanged to 36 months (6,506 ± 2,223 µm/mm2, P=1.0). Conclusions: Recovery of the central subbasal nerve fiber bundle density is less than half complete by 1 year after PRK, but by 2 years returns to densities not significantly different from densities before PRK.
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