The effect of hinge position and depth plate on the rate of recovery of corneal sensation following LASIK

PURPOSE: To evaluate and compare the effect of hinge position and flap thickness on recovery rate of corneal sensation after (LASIK). DESIGN: Prospective, randomized clinical study. METHODS: Forty eyes of 40 patients underwent LASIK to correct myopia ranging from -1.00 to -2.50 diopters. Corneal sensitivity was measured preoperatively and each month after surgery until recovery to preoperative level. The nasal,hinged ACS microkeratome (NH) with depth plates of 130 and 160 mum and the superior-hinged Hansatome microkeratome (SH) with depth plates of 160 and 180 mum were used for corneal flap creation. The eyes were divided into four groups according to the hinge position and depth plate (DP): group 1, NH and 130 mum DP; group 2, NH and 160 mum DP; group 3, SH and 160 mum DP; group 4, SH and 180 mum DP. 0 RESULTS: Corneal sensitivity returned to preoperative level after 3.7 (+/-0.4), 4.4 (+/-0.6), 5.4 (+/-0.8), and 5.8 (+/-0.9) months, respectively, in groups 1, 2, 3, and 4. Statistically significant differences were found between groups 1 and 2, but not between groups 3 and 4. Corneal sensitivity gradually returned to preoperative levels in all groups. Sensitivity of the hinge area was higher than other areas at every time point. CONCLUSIONS: The results suggest that after LASIK, hinge position and flap thickness seem to be important factors in the rate of return of corneal sensitivity. A thin flap with a nasally placed hinge is associated with the most rapid recovery of corneal sensitivity. (C) 2005 by Elsevier Inc. All rights reserved.