Reproducibility of corneal flap thickness in laser in situ keratomileusis using the Hansatome microkeratome

Purpose: To evaluate the reproducibility of flap thickness during laser in situ keratomileusis (LASIK) and to analyze the effect of preoperative centr al corneal thickness and corneal keratometric power on flap thickness. Setting: Department of Ophthalmology, Cerrahpasa Medical School, Istanbul, Turkey. Methods: One hundred forty eyes with a mean preoperative pachymetry of 554. 4 mum +/- 36.3 (SD) and a mean keratometry of 43.5 +/- 1.9 diopters had LAS IK using the Hansatome automated microkeratome (Bausch & Lomb Surgical) and a 193 nm argon-fluoride excimer laser (Summit SVS Apex Plus). The 180 mum microkeratome plate was used in all procedures. Corneal thickness was measu red with an ultrasonic pachymeter (Advent, Mentor O&O inc.) before and duri ng the flap procedure, and the difference was taken as flap thickness. The data were analyzed using a 1-tailed t test and Pearson correlation coeffici ent. Results: The mean flap thickness was 120.8 +/- 26.3 mum. There was a low co rrelation between baseline central corneal thickness and corneal flap thick ness (P =.6, r = 0.046). There was no correlation between preoperative kera tometry and flap thickness (P =.01, r = 0.203). Conclusions: The Hansatome microkeratome does not always produce a corneal flap of the intended thickness. Factors other than keratometry and pachymet ry must affect flap thickness. J Cataract Refract Surg 2000; 26:1729-1732 ( C) 2000 ASCRS and ESCRS.