Clinical analysis on the effects of laser-assisted subepithelial keratomileusis in treatment of super high myopia

Abstract

To assess the clinical efficacy and safety of LASEK in the treatment of super high myopia. It was a retrospective case series study. Fifty-six eyes of 33 cases with super high myopia were treated with LASEK. Mean spherical equivalent preoperative was (-11.70 +/- 1.59) D (range from -10.0 D to -15.13 D), mean ablation zone was (5.3 +/- 0.51) mm (range from 4.3 mm to 6.0 mm), mean ablation depth was (146.1 +/- 29.3) microm. The mean time of alcohol used treatment was (29.2 +/- 2.8) seconds. Postoperative follow-up assessments were performed at 1, 3, 6 and 12 months after surgery. Postoperative measurements included slit-lamp microscopy, manifest refraction, un-corrected visual acuity (UCVA), best corrected visual acuity (BCVA), intraocular pressure and haze, etc. The time of follow-up was more than one year. The results were analyzed with ANOVA by SPSS software. Fifty percent of eyes obtained UCVA of > or = 1.0, and 78.6% of eyes obtained UCVA > or = 0.6, at six months after operation. Forty-one percent eyes obtained UCVA of > or = 1.0, and 73.2% eyes obtained UCVA > or = 0.6 at one year postoperatively. The mean UCVA in Snellen chart was 0.85 +/- 0.20, 0.88 +/- 0.28, 0.84 +/- 0.26 and 0.83 +/- 0.28 at 1, 3, 6 and 12 months after operation, respectively. These data were transformed into lgMAR visual acuity and analyzed statistically. There was no significant statistically difference between UCVA at different follow-up periods (F = 0.749, P = 0.518). The postoperative UCVA compared to preoperative BCVA being the same/or improved in 71.4% eyes and decreased in 28.6% eyes at six months after operation; and was 64.3%, and 35.7% at one year after operation, respectively. The effective index was 0.994 and 0.992 at six and twelve months after operation, respectively. The postoperative BCVA compared to preoperative being the same (or improved) and decreased at six and twelve months after operation was 85.3% vs. 14.7%, and 84.8% vs. 15.2%, respectively. The mean BCVA in Snellen chart was 0.90 +/- 0.17, 0.94 +/- 0.24, 0.95 +/- 0.16 and 0.96 +/- 0.16 at 1, 3, 6 and 12 months after operation, respectively. These data were transformed into lgMAR visual acuity and analyzed statistically. There was no significant statistically difference between lgMAR BCVA at difference different follow-up periods (F = 1.567, P = 0.229). The safe index at 6 and 12 months were 1.009 and 1.010. The incidence of refraction regression at 3, 6 and 12 months after operation was 19.6%, 28.6% and 30.3%, respectively. Mean regressive diopter in regressed eyes at 3, 6 and 12 months after operation was (-1.20 +/- 1.08) D, (-1.23 +/- 0.75) D, (-1.49 +/- 1.04) D, respectively. Haze grade 0.5 was 21.4% at 3 months after operation; grade 0.5 and 1 were 8.9% and 5.4% at 6 months after operation, respectively, at 6 months after operation. Haze grade 0.5 was 12.5% at one year after operation. The incidence of high intraocular pressure induced by topical use of corticosteroid eye drop was 8.9%. LASEK is a safe and effective procedure for correction of super high myopia, though there is still some regression happened after operation and the intraocular pressure should be observed during the follow-up periods.