The effect of hinge poition and depth plate on the rate of recovery of corneal enation following LAIK

Purpoe To evaluate and compare the effect of hinge poition and flap thickne on recovery rate of corneal enation after (LAIK). Deign Propective, randomized clinical tudy. Method Forty eye of 40 patient underwent LAIK to correct myopia ranging from −1.00 to −2.50 diopter. Corneal enitivity wa meaured preoperatively and each month after urgery until recovery to preoperative level. The naal-hinged AC microkeratome (NH) with depth plate of 130 and 160 μm and the uperior-hinged Hanatome microkeratome (H) with depth plate of 160 and 180 μm were ued for corneal flap creation. The eye were divided into four group according to the hinge poition and depth plate (DP): group 1, NH and 130 μm DP; group 2, NH and 160 μm DP; group 3, H and 160 μm DP; group 4, H and 180 μm DP. Reult Corneal enitivity returned to preoperative level after 3.7 (± 0.4), 4.4 (± 0.6), 5.4 (± 0.8), and 5.8 (± 0.9) month, repectively, in group 1, 2, 3, and 4. tatitically ignificant difference were found between group 1 and 2, but not between group 3 and 4. Corneal enitivity gradually returned to preoperative level in all group. enitivity of the hinge area wa higher than other area at every time point. Concluion The reult ugget that after LAIK, hinge poition and flap thickne eem to be important factor in the rate of return of corneal enitivity. A thin flap with a naally placed hinge i aociated with the mot rapid recovery of corneal enitivity.