准分子激光原位角膜磨镶术后近视患者对比敏感度的变化

目的 评价准分子激光原位角膜磨镶术（laser in situ keratomileusis,LASIK)对近视患者静态近对比敏感度的影响。方法 使用功能性视力对比敏感度101测试表,对47例（93只眼）接受LASIK治疗的近视患者分别于术前,术后1个月和6个月检查空间频率为1.5,3.0,6.0,12.0及18．0周／度（cycle/degree,c/d)的静态近对比敏感度,并进行统计学分析。结果 LASIK术后1个月和6个月裸眼视力接近术前矫正视力。术后1个月术眼空间频率为12．0和18．0c/d的静态近对比敏感度低于术前,差异均有非常显著意义（P＜0．01）,术后6个月趋于恢复。术后1个月术前屈光度数≥－6.00D者和术后出现眩光和光晕现象者空间频率为6.0,12.0及18.0c/d的对比敏感度下降率分别大于屈光度数＜-6.00D者和术后无眩光和光晕现象者（P＜0．05）。结论 对比敏感度检查可敏感,全面地反映患者和视功能状态,利于临床对视觉问题进行及时,有效的诊断,弥被临床仅依据视力评价LASIK疗效的不足。

Contrast sensitivity function in myopic LASIK

OBJECTIVE: To evaluate near contrast sensitivity function before and after myopic laser in situ keratomileusis (LASIK). METHODS: With FACT 101 test chart, static near contrast sensitivity was measured in randomly selected 47 subjects (93 eyes) before, 1 month and 6 months after LASIK. The contrast sensitivity was measured at 1.5, 3.0, 6.0, 12.0 and 18.0 cycles per degree (c/d) spatial frequency respectively and made comparison in them. RESULTS: The patients achieved the mean uncorrected visual acuity (UCVA) of 1.07 +/- 0.18 and 1.12 +/- 0.20 at postoperative 1-month and 6-months respectively. There was a general reduction in near contrast sensitivity in all spatial frequencies at postoperative 1-month when they were compared with the preoperative contrast sensitivity. The difference at 12 and 18 c/d spatial frequency was statistically significant (t test, P < 0.01). By the 6-month visit, all eyes showed a recovery of static contrast sensitivity function. The group of high myopia (preoperative > or = -6.00 D) and group with complaining of glare and halos after the surgery had a higher decrease rate of contrast sensitivity compared with that of the group preoperative < - 6.00 D and the group of patients without such complaints respectively. The differences at 6.0, 12.0 and 18.0 c/d spatial frequency at 1-month visit was statistically significant (t test, P < 0.05). CONCLUSIONS: The contrast sensitivity function test offers a more sensitive and comprehensive measure of functional vision than does standard Snellen acuity. The near contrast sensitivity in post-LASIK patients at early stage is reduced despite normal visual acuity and this can affect the quality of vision.