To evaluate the reproducibility of flap thickness during laser in situ keratomileusis (LASIK) and to analyze the effect of preoperative central corneal thickness and corneal keratometric power on flap thickness.
Department of Ophthalmology, Cerrahpasa Medical School, Istanbul, Turkey.
One hundred forty eyes with a mean preoperative pachymetry of 554.4 μm ± 36.3 (SD) and a mean keratometry of 43.5 ± 1.9 diopters had LASIK using the Hansatome automated microkeratome (Bausch & Lomb Surgical) and a 193 nm argon–fluoride excimer laser (Summit SVS Apex Plus). The 180 μm microkeratome plate was used in all procedures. Corneal thickness was measured with an ultrasonic pachymeter (Advent, Mentor O&O Inc.) before and during the flap procedure, and the difference was taken as flap thickness. The data were analyzed using a 1-tailed t test and Pearson correlation coefficient.
The mean flap thickness was 120.8 ± 26.3 μm. There was a low correlation between baseline central corneal thickness and corneal flap thickness (P = .6, r = 0.046). There was no correlation between preoperative keratometry and flap thickness (P = .01, r = 0.203).
The Hansatome microkeratome does not always produce a corneal flap of the intended thickness. Factors other than keratometry and pachymetry must affect flap thickness.