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JC Erie, SV Patel, JW McLaren, CB Nau, WM Bourne; Keratocyte Density Three Years After Myopic Photorefractive Keratectomy (PRK) . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4133.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:: Previously we reported changes in keratocyte density in the first year after myopic photorefractive keratectomy (PRK). In this study we examined the same cohort to determine changes in keratocyte density between one and three years after PRK. Methods: Eighteen eyes of 13 patients underwent PRK (VISX Star) with epithelial removal by laser scrape to correct -1.50 to -7.25 diopters and remained in the study for 3 years without reoperations. Central corneas were examined preoperatively and at 1, 2, and 3 years after PRK by using confocal microscopy. Bright objects (keratocyte nuclei) were manually counted by a masked observer in 10 images without motion blur in 1 full-thickness scan from each examination. Cell densities were determined in five anteroposterior stromal layers. In the pre-PRK cornea, the boundaries of the stromal layers were determined: 1) relative to the stroma that would remain after the ablation (the thickness of ablated stroma, as measured 1 month post-PRK, was omitted from the analysis to allow comparison of the same tissue) and 2) relative to the original full-thickness stroma. Results: Keratocyte density remained unchanged in all stromal layers at 1, 2, and 3 years post-PRK when compared to the same tissue of the pre-PRK stroma (paired t-test, P ≷ 0.05). However, keratocyte density in the anterior 0-10% stromal layer was decreased by 39% (P < 0.001), 38% (P < 0.001), and 43% (P < 0.001) at 1, 2, and 3 years post-PRK respectively, when compared to the corresponding layer of the original full-thickness pre-PRK stroma. Cell densities were unchanged in the remaining corresponding layers of the original full-thickness pre-PRK stroma (P ≷ 0.05). Conclusion: Three-years post-PRK, keratocyte density in the anterior stroma is not restored to the high population density found in the corresponding anterior stroma of the original, unoperated cornea.
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