The Clinical Results Of Epi-LASIK For The Treatment Of Myopia And Myopic Astigmatism

Purpose:To evaluate the clinical results of Epi-LASIK for the treatment of myopia and myopic astigmatism by comparing postoperative refractive outcome,visual acuity,posterior corneal elevation(the value of Diff) and visual quality of Epi-LASIK versus those of LASIK and IntraLase.Methods:The nonrandomized clinical study involved a total of 48 eyes of 24 patients,with 24 eyes of 12 patients comprising the Epi-LASIK group,14 eyes of 7 patients comprising the LASIK group and 10 eyes of 5 patients comprising the IntraLase group.The differences in age, preoperative spherical equivalent and intended correction were not statistically significant(P＞0.05).Refractive errors,visual acuity,posterior corneal elevation(the value of Diff), higher-order aberrations,contrast sensitivity,and accommodative functions were compared in the three groups.RESULTS:There were no statistically significant differences in terms of loss best-corrected visual acuity(x~2=2.379,P=0.392),although 4(16.67%)eyes loss of best-corrected visual acuity more than 2 lines in Epi-LASIK;none in LASIK and leye loss 2 lines,leye loss 1 line in IntraLase.The mean spherical equivalent at 1 month postoperatively was 0.13±0.18D in Epi-LASIK and -0.16±0.34D in LASIK and 0.04±0.62D in IntraLase,respectively.Although the percentage of the mean difference between achieved and intended spherical equivalent within±0.5 D were significantly lower in Epi-LASIK treated eyes(37.5%)than in IntraLase -treated eyes (80%) and LASIK-treated eyes(100%)(x~2=17.399,P＜0.05),they were similar within±1.0 D(x~2=3.035,P=0.169).At 1 month postoperatively,posterior corneal elevation(the value of Diff)were significantly increased in three groups(F=78.355,P＜0.01).The higher-order aberrations and accommodative functions were similar in three groups(P＞0.05),except for trefoil aberration,which decresed greater in the Epi-LASIK group(P＜0.05).Under mesopic with or without glare conditions,the contrast sensitivity value was significantly improved at one month postoperatively in the Epi-LASIK and IntraLase group and decreased in LASIK group except at 1.5 and 18 cycles per degree in the Epi-LASIK group under mesopic without glare conditions(P＜0.05). CONCLUSIONS:Epi-LASIK is a safe and efficient method for the correction of myopia and myopic astigmatism with the advantage that it has only mild symptoms and mild haze.The Epi-LASIK may have significant superiority over the LASIK in early visual quality which is near to IntraLase,although it failed to have as good early visual acuity and predictability as IntraLase and LASIK.A larger randomized double-blind study with longer follow-up is needed to determine its long-term clinical results.