Flap dimensions created with the Hansatome microkeratome: correlation with Orbscan-derived anterior segment data.

Purpose: To investigate the flap dimensions created by Hansatome microkeratome (Bausch & Lomb Surgical) and their correlation with anterior segment biometric data measured by the Orbscan II (Bausch & Lomb).

Setting: Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey.

Methods: Forty-four myopic eyes of 22 patients (mean age 29 years +/- 7 [SD]) that had laser in situ keratomileusis surgery using the Hansatome microkeratome were enrolled in the study. Intraoperative images taken from video recordings of procedures were analyzed with image analysis software to determine flap size and hinge size. White-to-white corneal diameter, corneal curvatures (K(max), K(min)), corneal thickness, and anterior chamber depth were deducted from Orbscan measurement. Correlation analyses between flap dimensions and Orbscan-derived anterior segment biometric data were done.

Results: The mean corneal flap diameter was 9.56 +/- 0.28 mm in the right eye and 9.62 +/- 0.28 mm in the left eye. There was no difference in flap size between the right and left eyes (P=.43). The mean hinge size was 4.98 +/- 0.37 mm in the right eye and 5.07 +/- 0.41 mm in the left eye. There was no difference in hinge size between the right and left eyes (P=.46). There was a significant correlation between flap size and preoperative corneal thickness (P<.001, r=0.487), but there was no correlation between flap size and corneal curvature (P=.40, r=-0.12), white-to-white corneal diameter (P=.11, r=0.47), or anterior chamber depth (P=.52, r=0.09). There was also no correlation between hinge size and preoperative anterior segment biometric data.

Conclusion: The Hansatome microkeratome produced a flap whose diameter is close to the intended flap diameter, and preoperative corneal thickness seems to be the important factor in determining flap size.