Comparative evaluation of ‘flap on’ and ‘flap off’ techniques of Epi-LASIK in low-to-moderate myopia

Abstract

Comparative evaluation of 'flap on' and 'flap off' techniques of Epi-LASIK in low-to-moderate myopia. Sixteen eyes of eight consecutive patients with myopia < or = 6 D were selected for this prospective, randomized, comparative, interventional case series. Epi-LASIK surgery was performed in all eyes. In one eye of each patient, the epithelial flap was retained after excimer laser ablation (flap on). In the fellow eye, the epithelial flap was discarded (flap off) after ablation. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), spherical equivalent (SEQ), postoperative pain score, time to epithelization, and corneal haze were recorded on postoperative visits. The mean preoperative SEQ in the two groups was -3.61+/-1.32 D (flap on) and -3.49+/-1.86 D (flap off; P=0.752). The mean follow-up period was 8.5+/-4.9 months. The mean pain score was comparable on all postoperative days except the second postoperative day when the group with flap off had a lesser mean pain score (P=0.053).Time for epithelial healing was 3.63+/-0.52 days in cases with flap off and 4.13+/-0.64 days in cases with flap on (P=0.113). Eyes with flap off had a better UCVA on the first postoperative day (0.19+/-0.11 logMAR) compared with eyes with flap on (0.41+/-0.28 logMAR; P=0.032). There was no significant difference in UCVA, BSCVA, SEQ, contrast sensitivity, corneal haze, and higher order aberrations at any other postoperative visit. There is no difference between flap on and flap off techniques of Epi-LASIK with regards to overall outcome of surgery.