Visual and Refractive Outcome of Epi-LASIK for Myopia in Thin Corneas: a 12-Month Follow-Up

Abstract

Purpose. A nonrandomized, retrospective, cohort, single-center study was designed to examine the visual and refractive outcome of epi–laser-assisted in situ keratomileusis (LASIK) for myopia (with and without astigmatism) in patients with thin corneas (less than 500 µm), and to compare these results with those of a group of patients with normal corneal thickness. Methods. Uncorrected distance visual acuity (UCVA), spherical and cylindrical residual refractive error, mean keratometry readings (Km), and pupil diameter were measured postoperatively at 24 hours, 1 week, 1 month, 3 months, and 12 months in a group of 28 eyes with thin corneas (group 1) and a second age- and gender-matched group of 28 eyes with normal corneal thickness (group 2). In addition, the efficacy index was calculated at every postoperative examination. Results. Postoperative central corneal thickness was 464.14±50.40 µm in group 1 and 421.89±26.63 µm in group 2 (p<0.001). No statistically significant difference was found in UCVA, efficacy index, and spherical and cylindrical residual error between both groups, with an evolution towards stability over time in all cases. Statistically significant between-group differences in Km at all follow-up examinations were explained by between-group differences in ablation depth and attempted spherical correction. Conclusions. A 12-month follow-up revealed epi-LASIK for myopia (with and without astigmatism) to be a safe and predictable surface ablation procedure, with good visual and refractive outcome in patients with thin corneas, as compared with a group of patients with normal corneal thickness.