Comparison of clinical results between flap-on and flap-off techniques of epithelial-laser in situ keratomileusis in correction of low to moderate myopia in eyes with thin corneas

Purpose: To prospectively compare flap-on and flap-off techniques of epithelial-laser in situ keratomileusis (epi-LASIK) for the correction of low to moderate myopia in patients with thin corneas. Methods: In this randomized, interventional study, the cohort was comprised of 88 eyes (44 patients) with myopia which underwent epi-LASIK. The epithelium was separated as a 9 mm flap with 2–4 mm nasal hinge with epikeratome (Lasatom, Gebauer Medizintechnik GmbH, Neuhausen, Germany) and the ablation was performed with the MEL 80 excimer laser (Carl Zeiss, Meditec,Jena, Germany). Thirty-eight eyes underwent flap-on Epi-LASIK where the flap was repositioned after ablation (flap-on group) and 50 eyes underwent flap-off Epi-LASIK where the epithelial flap was discarded (flap-off group). Pre- and post-operative uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), and spherical equivalent (SE) were collected for each group. Post-operative pain, time to epithelialization, and corneal haze were also collected postoperatively. Variables were compared with the paired t-test, chi-squared test and one-way analysis of variance. Statistically significance was indicated by p 0.05. Results: The mean preoperative SE was -3.89 ± 1.9 diopters (D) for the flap-on group and -3.92 ± 2.17 D for the flap-off group (p = 0.96). The mean follow-up was 12 months. The mean pain score was comparable on all postoperative days except the 2nd postoperative day where the flap-on had significantly lower mean pain scores (p = 00). Time for epithelial healing was 4.39 ± 0.49 days in flap-on group and 4.64 ± 0.69 days in flap-off group (p = 0.07). There was no significant difference in the postoperative UCVA between groups (p = 0.77). Corneal haze at the end of postoperative follow-up was not different between groups (p =0.217). Conclusion: There is no significant difference in the clinical outcomes between flap-on and flap-off techniques of Epi-LASIK for the correction of low to moderate myopia.