The Effect of Environmental Humidity on LASIK Results

Choi, Byeong Gil; Cho, Beom Jin; Choi, Kee Yong

Abstract

It is known that humidity in the laser room might affect the outcomes of excimer laser refractive surgery. This study evaluated the outcomes of laser in situ keratomileusis (LASIK)according to humidity changes in laser room. Hinged flap was made by SCMD turbokeratome and photoablation was performed by utilizing VISX 20/20 excimer laser system. The differences between targeted refraction and actual refractive error, namely, refractive correction errors (defined by authors)were calculated. We have divided LASIK patients into two groups. Group A consisting of 61 eyes of 31 patients underwent LASIK when laser room humidity was over 70% (average 73%) and Group B includes 49 eyes of 28 patients when laser room humidity was under 40% (average 35%). Each group was broken into two subgroups, that is high myopia (> or= -6 D)and mild to moderate myopia (< -6 D). The mean refractive correction errors in the high myopia (> or= -6 D)was 1.28+/-1.42 D in the group A (n=46 eyes)and 1.99 +/-1.38 D in the group B (n= 26 eyes). In both groups, the difference between two subgroups was statistically significant and high myopes group B was overcorrected compared with ones in group A (t-test, p<0.05). The mean refractive correction errors in the low to moderate myopia (< -6 D)was 0.38 +/-0.49 D in the group A (n=15 eyes)and 0.4 +/-0.38 D in the group B (n=23 eyes). In both subgroups, there was no statistically significant difference in mean refractive correction errors (t-test, p>0.05). The proper room humidity is critical for LASIK results, particularly in the high myopia (> or= -6 D)because humidity can affect outcomes of LASIK. Therefore, the humidity should be maintained properly for enhancement of surgical outcome predictability in the high myopia.