LASIK术后中长期暗视下对比敏感度观察

目的观察比较近视患者戴镜矫正后与准分子激光原位角膜磨镶术(LASIK)后1a以上、裸眼视力1.0以上的患者,在暗视下有和无眩光下对比敏感度的变化。方法以MesotestⅡb对比敏感度仪(德国Oculus公司)检测暗环境下有和无眩光时的对比敏感度,其背景亮度分别为无眩光情况下(0.032±0.003)cd.m-2和有眩光时(0.100±0.010)cd.m-2共4个对比度8个等级。其中对照组近视患者72例,最佳矫正视力(BCVA)≥1.0,等后残存等效球镜度数(0.24±0.58)D。结果暗视下无眩光情况,试验组未通过检测的发生率:grade112.3%、grade223.6%、grade344.9%、grade464.0%,均高于对照组(grade10%、grade21.4%、grade39.7%、grade425.0%),差异均有统计学意义(均为P<0.05)。暗视下有眩光情况,试验组各等级未通过率:grade513.4%、grade616.8%、grade730.3%、grade840.4%,高于对照组(grade51.3%、grade62.7%、grade74.1%、grade829.1%);5～7等级比较,差异也均有统计学意义(均为P<0.05)。试验组有眩光情况下三个对比度等级(15、12.7、12.0)的未通过率低于无眩光,其中1:2.7、1:2.0两个等级更为明显,差异均有统计学意义(均为P<0.05)。结论 LASIK术后患者尽管裸眼视力达到正常,并且术后恢复1a以上,暗视下对比敏感度仍低于未手术的近视患者;背景光亮度对术后患者暗视下对比敏感度有较明显的影响。

Contrast sensitivity after LASIK under mesopic conditions

Objective To analyze and compare the changes of contrast sensitivity in myopic patients with the time more than 1 year after and wearing glasses correction and naked visual acuity more than 1.0 under scotopia with or without glare.Methods Contrast sensitivity with or without glare was determined by Mesotest IIb(Oculus,Germany) under scotopia.During the test,there were 4 contrast levels and 8 grades,and the background luminance was(0.032±0.003)cd·m-2 without glare and(0.100±0.010)cd·m-2 with glare.The spherical equivalent of myopic patients(72 cases) in control group was from-1.00 D to-8.00 D and the best corrected visual acuity was equal to or more than 1.0;The visual acuity of myopic patients(89 cases) in test group was equal to or more than 1.0 and the postoperative remnant spherical equivalent was(0.24±0.58)D.Results Under scotopia without glare,the proportion of patients unable to discriminate the scotopia contrast limits of grade 1,2,3,4 in test group were 12.3%,23.6%,44.9% and 64.0%,respectively,which were higher than that in control group(0%,1.4%,9.7%,25.0%),there were statistical differences(all P<0.05);Under scotopia with glare,the proportion of patients unable to discriminate the scotopia contrast limits of grade 5,6,7,8 in test group were 13.4%,16.8%,30.3% and 40.4%,respectively,which were higher than that in control group(1.3%,2.7%,4.1%,29.1%),there were statistical differences(all P<0.05).The proportion of patients unable to discriminate the scotopia contrast limits of levels(1:5,1:2.7,1:2.0) in test group under scotopia with glare was lower than that without glare,in which the levels 1:2.7 and 1:2.0 were more obvious,there were statistical differences(all P<0.05).Conclusion Even for the postoperative time is more than one year,and the naked visual acuity is restored to normal,the contrast sensitivity under scotopia in patients with LASIK is still worse than that in patients without LASIK,and the effect of background luminance on contrast sensitivity under scotopia after LASIK is obviously.