AIM: To observe the flap characteristics and the factors correlated to the thickness of the cornea flap created with mechanical microkeratome in sub-bowman's keratomileusis(SBK).

METHODS: One hundred and ninety-six consecutive eyes of 98 patients were treated with Moria One Use-Plus SBK microkeratome. The intended flap thickness was 100μm. The flap thickness was measured by A type ultrasound. The flap complications were recorded and single variable correlations of the flap thickness and preoperative MRSE, corneal diameter, corneal thickness, corneal keratometric value K were determined.

RESULTS: The mean flap thickness was 100.96±5.35μm, mean flap thickness was 103.56±5.22μm in the left eyes and 98.12±5.50μm in the right eyes, the difference between right and left eyes was statistically significant(t=2.36, P<0.05). The uniformity of corneal flap was good. There were no statistical differences on corneal thickness at cornea center, nasal side, temporal side and 3mm from the center at the top and bottom(F=0.438,P>0.05). Corneal flap thickness was positively correlated with preoperative corneal keratometric value K(r=0.452, P<0.01)and preoperative central corneal thickness(r=0.312, P<0.05), but was not dependent on preoperative MRSE and corneal diameter. The common complications were top flap edge bleeding(34 eyes), root flap edge roughness(38 eyes)and tiny folds(25 eyes), with no other complications.

CONCLUSION: The corneal flaps created by mechanical microkeratome in SBK have even thickness, good predictability and fewer complications, and are positively correlated with preoperative corneal keratometric value K and preoperative central corneal thickness.