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C.B. Nau, J.W. McLaren, D.O. Hodge, W.M. Bourne; Prospective 3-Year Longitudinal Evalutation of Keratocyte Density After LASIK . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2583.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine changes in keratocyte density 1, 2, and 3 years after laser in situ keratomileusis (LASIK). Methods: Seventeen eyes of 11 patients received LASIK (VISX Star) with a planned 180-µm flap (Hansatome) to correct refractive errors between -2.0 D and -11.0 D (no eyes were retreated). Central corneas were examined by using confocal microscopy (Tandem Scanning, Reston, VA) before LASIK and at 1, 2, and 3 years after LASIK. Bright objects (that resembled keratocytes) were manually counted by one observer in select images without motion blur, presented randomly. Cell densities were determined in the anterior and posterior halves of the stromal flap, the anterior and posterior halves of the layer 100 µm-thick immediately behind the ablation (retro-ablation zone, RAZ), the posterior 66-90% of the stroma, and the posterior 90-100% of the stroma. The region of stroma that was ablated (as measured by confocal microscopy at 1 month after LASIK) was omitted from the preoperative analysis. Densities were compared by using a one-factor repeated measures analysis of variance; siginificant differences were adjusted for multiple comparisons using the Student-Newman-Kuels procedure. Results: Keratocyte density was decreased in the anterior flap, posterior flap (Friedman's test), anterior RAZ, and posterior RAZ (Friedman's test) at all times compared to pre-LASIK densities (P<0.001). Density did not change in the posterior third of the stroma from pre-LASIK at any time (66-90%, P=0.18; 90-100%, P=0.13). Compared with pre-LASIK (21,649 ± 3,201 cells/mm3, mean ± SD), total keratocyte density (averaged through the total thickness) was lower (P=0.003) at 1 year (19,119 ± 2,262 cells/mm3) and 3 years (19,496 ± 1, 261 cells/mm3), but not at 2 years (20,340 ± 1,918 cells/mm3). Conclusions: After LASIK, keratocyte density decreases in the anterior flap, posterior flap, anterior RAZ, and posterior RAZ, and remains decreased for at least 3 years.
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