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Reproducibility of corneal flap thickness in laser in situ keratomileusis using the Hansatome microkeratome
R Yildirim1, C Aras, A Ozdamar
1Cerrahpasa Medical Faculty, Department of Ophthalmology, Istanbul, Turkey. reny@turk.net
Purpose:
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.
Setting:
Department of Ophthalmology, Cerrahpasa Medical School, Istanbul, Turkey.
Methods:
One hundred forty eyes with a mean preoperative pachymetry of 554.4 microm +/- 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 microm 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.
Results:
The mean flap thickness was 120. 8 +/- 26.3 microm. 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).
Conclusions:
The Hansatome microkeratome does not always produce a corneal flap of the intended thickness. Factors other than keratometry and pachymetry must affect flap thickness.