Corneal flap thickness in laser in situ keratomileusis using an SCMD manual microkeratome

PURPOSE: To evaluate corneal flap thickness in laser in situ keratomileusis (LASIK) and to measure variables correlated with corneal flap thickness. SETTING: Kangnam St. Mary's Hospital, Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea. METHODS: This prospective study comprised 69 eyes of 66 patients having LASIK with the VISX Star laser and SCMD manual microkeratome. Corneal thickness, keratometry, and refractive error were measured preoperatively, the time taken to complete the corneal flap and its thickness were recorded intraoperatively, and visual outcome was followed postoperatively. Corneal flap thickness was calculated as the thickness of the corneal stromal bed subtracted from the total corneal thickness. RESULTS: Mean corneal flap thickness was 137.18 microns +/- 33.66 (SD). The thickness in 32 eyes (46.4%) was less than 135 microns, in 17 eyes (24.6%) from 135 to 165 microns, and in 20 eyes (29.0%) greater than 165 microns. There was no relationship between corneal flap thickness and degree of myopia, steepening of cornea, or time taken to complete the flap. However, the thickness of the corneal flap increased with the thickness of the cornea. Visual outcome was slightly better in the group with thick corneal flaps than in the one with thin corneal flaps, although the difference was not statistically significant. CONCLUSION: Corneal flap thickness was variable in LASIK using the SCMD microkeratome. There was a correlation between corneal flap thickness and preoperative corneal thickness.