A control-matched comparison of flap off and flap on laser-assisted subepithelial keratectomy (LASEK) for the treatment of myopia and myopic astigmatism

PURPOSE: To compare the visual and refractive outcomes of flap off and flap on, Laser Assisted Subepithelial Keratectomy (LASEK) for low to moderate myopia. METHODS: A prospective non-randomized control-matched study was conducted in which 53 patients underwent LASEK for the treatment of low to moderate myopia and myopic astigmatism. Right eye of each patient had the flap removed (flap off) while in the left eye the flap was recapped (flap on). Equal number (N = 53) of flap on was matched with flap off having preoperative manifest refraction spherical equivalent within ±0.75 Diopters (D). Primary outcome variables included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA) and manifest refraction. RESULTS: Preoperatively, the mean spherical equivalent (SE) was −3.59 ± 1.46 D for flap off and −3.67 ± 1.51 D for flap on (p = 0.779). The mean preoperative sphere was −3.32 ± 1.58 D for flap off group and −3.36 ± 1.61 D for flap on group (p = 0.338) whereas, the mean preoperative cylinder was −0.55 ± 0.70 D and −0.63 ± 0.68 D for flap removal and flap preservation groups respectively (p = 0.576). Postoperatively, the mean LogMAR UCVA was −0.035 ± 0.079 for flap off and −0.043 ± 0.085 for flap on. The percentages of eyes that had UCVA of 20/40 or better were 98.1% for flap off group and 100% for flap on group (p = 0.317). Mean postoperative SE was 0.00 ± 0.19 D for flap off group and −0.03 ± 0.43 D for flap on group. In flap removal group, 100% eyes were within ±0.50 D of the intended correction while in flap preservation group, 92.5% and 100% eyes were within ±0.50 D and ±1.00 D of the intended correction, respectively. Mean postoperative LogMAR BSCVA was −0.013 ± 0.044 for flap removal group and −0.016 ± 0.049 for flap preservation group (p = 0.727). CONCLUSIONS: The differences in the visual and refractive results between flap preservation and flap removal groups were not clinically significant. Both procedures seemed safe and effective for the treatment of myopia and myopic astigmatism.