Abstract
Abstract: :
Purpose: The effect of stromal hydration on ablation depth has been well documented. However, the effect of ambient humidity on laser in situ keratomileusis (LASIK) outcomes is not clear. This study examines the effect of ambient humidity on LASIK outcomes. Methods: The study is a retrospective chart review of 199 patients who underwent LASIK at a private laser center from 1999 to 2001. The patients were treated by the same surgeon using the Bansal nomogram on the VISXâ excimer laser system. The data was stratified by relative humidity. We compared the LASIK outcomes in two subsets of 10 patients who were treated under the highest and lowest ambient humidity conditions . Results: The ten patients who underwent LASIK under the highest relative humidity (48-52%) and the ten patients treated under the lowest relative humidity (13-21%) were compared, totaling 39 eyes of 20 patients. The male to female ratio was 2:3 in both groups, average age was 39.3 (+/- 8.3) and 45.2(+/- 6.3) respectively, pre-op spherical equivalent (S.E.) was -5.45(+/-1.90) diopters and -4.47(+/-1.42) diopters respectively. The resultant correction compared to the refractive goal was 0.30(+/-0.38) D undercorrection in the high humidity group and 0.07(+/-0.36) D in the low humidity group, p<0.05. The relationship of the laser setting compared to the surgically induced refractive change (using the least squares method) had a slope of -1.00 in the high humidity group, compared to a slope of -1.13 in the low humidity group, suggesting a greater ablation in the low humidity group. Conclusion: During the LASIK procedure there are many variables which influence the surgical outcome. Ambient relative humidity does affect the LASIK outcome.
Keywords: 454 laser • 548 refractive surgery: LASIK