泪膜稳定性对飞秒激光辅助LASIK术后视觉质量的影响

Effect of tear film stability on visual quality after femtosecond laser-assisted LASIK

背景目前干眼发病率较高，干眼患者泪膜不稳定可严重影响飞秒激光辅助角膜原位磨镶术（FS-LASIK）术后术眼的视觉质量。以往泪膜和视觉质量检测方法的局限性影响了FS-LASIK术后视觉质量的预期。采用客观定量的泪膜稳定性和视觉质量检测方法，术前及时改善早期干眼患者的泪膜稳定性具有重要的临床意义。目的探讨FS-LASIK手术前后术眼泪膜质量对客观视觉质量的影响。方法采用前瞻性队列研究方法，于2015年8-12月在南京市第一医院纳入符合常规手术适应证、术前矫正视力≥5．0的近视患者120例120眼，术前客观散射指数（OSI）值均〈1．2。按照《干眼临床诊疗专家共识（2013年）》中关于轻度干眼的诊断标准和检查结果将患者分为轻度干眼组71眼和非干眼组49眼，2个组间人口基线特征匹配。非干眼组术眼接受FS-LASIK，轻度干眼组使用质量分数0．1％玻璃酸钠滴眼液点眼1个月后接受FS—LASIK。所有患者于术前及术后1、3、6、12个月行裂隙灯显微镜、裸眼视力（UCVA）、最佳矫正视力（BCVA）、等效球镜度（sE）、基础泪液分泌试验（sIt）、泪膜破裂时间（BUT）检查并评价术眼安全指数和有效指数；采用OQAS“Ⅱ客观视觉质量分析系统测定调制传递函数截止频率（MTFcutoff）和OSI。结果非干眼组和轻度干眼组术眼的安全指数分别为1．05±0．11和1．03±O．09，有效指数分别为1．02~0．14和1．0l±0．12，差异均无统计学意义（t=0．391、0．147，均P〉0．05）；非干眼组和轻度干眼组术眼术后1个月和3个月BUT较术前均明显缩短，术后6个月恢复至术前水平，轻度干眼组术眼术后3个月BUT值明显低于非干眼组，差异均有统计学意义（均P〈O．05）；术后1、3和6个月非干眼组和轻度干眼组术眼平均OSI值较术前明显增加，同时间点轻度干眼组术眼平均OSI值明显高于非干眼组，差异均有统计学意义（均P〈O．05）；非干眼组和轻度干眼组术后1、3和6个月术眼MTFcutoff值均明显低于各自的术前值，术后6个月轻度干眼组术眼MTFcutoff值明显低于非于眼组，差异均有统计学意义（均P〈0．05）。术后12个月，非干眼组和轻度干眼组术眼BUT、平均OSI值和MTFcutoff值均接近术前水平。结论FS-LASIK术后可获得较好的客观视觉质量，术前泪膜稳定性与术后客观视觉质量的动态变化趋势一致。于眼患者的泪膜不稳定对人眼的多个视觉质量指标造成影响；OQAS-II系统可早期发现和随访监测干眼的泪膜变化，有助于屈光不正患者手术适应证筛选和对术眼术后视觉质量进行合理预测。

Background The instability of tear film in dry eye often affects the visual quality after femtosecond laser-assisted laser in situ keratomileusis （FS-LASIK）. The prediction for visual quality following FS- LASIK was difficult in the past because of the limiting of examination method. OQAS-II is a quantitative checking system of visual quality, which is helpful for the evaluation of the relationship between tear stability and visual quality following FS-LASIK. Objective This study was to investigate the predicting effects of the quality of tear film on visual quality after LASIK. Methods A prospective cohort study was performed. One hundred and twenty eyes of 120 myopic patients who wanted to receive FS-LASIK were enrolled in Nanjing First Hospital from August to December 2015 after informed consent. The objective scattering index （OSI） was 1.2 in the patients. The patients were divided into mild dry eye group （71 eyes） and non-dry eye group （4-9 eyes） based on the Expert Consensus on Clinical Diagnosis and Treatment of Dry Eye（2013）. FS-LASIK was performed in the non-dry eye group,and 0. 1% sodium hyaluronate eye drops was topically administered for 1 month firstly and then the operation was carried out in the same way in the mild dry eye group. Slit lamp microscope, uncorrected visual acuity （UCVA） , best corrected visual acuity （BCVA）,spherical equivalent （SE） were examined, and the safety index and availability index were assessed. OQASTM Ⅱ analysis system was employed for the defection of Schirmer ] test （S I t） ,breakup time of tear film （BUT） ,modulation transfer function cut-off frequency （MTF cut off） and mean OSI before and after surgery. Results The safety index was 1.05±0. 11 and 1.03 ±0. 09, and the availability index was 1.02±0. 14 and 1.01 ±O. 12 in the non-dry eye group and mild dry eye group,respectively,showing significant differences between the two groups （t=0. 391,0. 147,both at P〉O. 05）. The BUT was evidently shortened 1 month and 3 months after surgery in comparison with before surgery in both non-dry eye group and mild dry eye group, and BUT in the mild dry eye group was shorter than that in the non-dry eye group in postoperative 3 months,with a significant differences between them （P〈O. 05）. The mean OSI was increased and MTF cutoff was reduced 1 month,3 months and 6 months after surgery in comparison with before surgery in both mild dry eye group and none-dry eye group,and mean OSI was higher and MTF cutoff was lower in the mild dry eye group than that in the non-dry eye group,with significant differences between them （all at P〈0.05 ）. In postoperative 12 months, BUT,mean OSI and MTF cutoff were near normal in both groups. Conclusions FS-LASIK can improve objective visual quality, and preoperative tear film quality is associated with objective visual quality after FS-LASIK. The unstable tear film affects visual quality after FS-LASIK. OQASTM 11 system can diagnose and monitor tear change of dry eyes, which is helpful for the screening of indicator of FS-LASIK and rational prediction of postoperative visual quality.