干眼对年龄相关性白内障患者人工晶状体度数测量和计算准确性的影响

Pilot study on dry eye affecting the accuracy of intraocular lens power measurement in age-related cataract

背景近年来干眼的患病率逐渐增加，人口老龄化进程的加快是其因素之一。研究已证实泪膜稳定性的改变可引起角膜屈光力变化，而角膜屈光率的变化可影响人工晶状体（IOL）度数的测量和计算，因此干眼对年龄相关性白内障患者术前IOL预测的影响值得关注。目的探讨干眼对年龄相关性白内障患者IOL度数计算和预测准确性的影响。方法采用前瞻性非随机对照的临床研究方法，纳入2013年5月至2014年2月在延边眼耳鼻喉科医院眼科拟行超声乳化联合IOL植入术的年龄相关性白内障患者216例216眼，术前进行视力检查、眼压测定以及干眼相关检查，包括泪膜破裂时问（BUT）、泪液分泌试验（SIt）、角膜荧光素染色检查。根据干眼程度分为轻度干眼组（73眼）、重度干眼组（68眼）和非干眼对照组（75眼）。利用IOL Master测量受检跟眼轴长度（AL）和前房深度（ACD），计算角膜曲率（K）值和IOL度数。术后2个月采用KR8100全自动电脑验光仪测定术眼实际屈光度，计算术后实际屈光度与术前预测屈光度间的平均绝对屈光误差，比较干眼组与非干眼组间受检眼在不同屈光误差范围的百分比，分析干眼相关测定参数与术前K值及术后屈光误差之间的关系。结果轻度干眼组、重度干眼组和非干眼对照组间受检者性别和年龄、受检眼AL、ACD及MARE的差异均无统计学意义（均P〉0．05），但各组间BUT、SIf、角膜染色评分、角膜K值的总体比较差异均有统计学意义（F=5．460、4．521、3．572，均P〈0．05）。轻度干眼组、重度干眼组和非干眼对照组受检眼K值分别为（43．59±1．39）、（44．66±1．53）和（43．42±1．32）D，其中重度干眼组受检眼K值明显高于非干眼对照组，差异有统计学意义（P=0．012）。术后屈光误差为＋0．50～＋0．75D时干眼组受检眼的百分比明显高于非干眼对照组（28．8％与13．3％），而屈光误差在-0．50- -0．75D时干眼组受检眼的百分数明显低于非干眼对照组（17．3％与28．0％），差异均有统计学意义（r=4．513，P=0．032；X2=4．236，P=0．037）。BUT与角膜K值呈显著负相关（r=-0．204，P=0．011）。结论干眼可影响白内障术前IOL度数测定的精确性，其术后的屈光度较术前预测值轻度偏向远视。

Background The incidence of dry eye is gradually increasing,and the aging of population is one of factors. Researches showed that the change of tear film stability leads to shift of corneal refractive power, which probably affects the measurement of intraocular lens （IOL） power. The influence of dry eye on the calculation of IOL power is worth paying close attention. Objective This study was to investigate the influence of dry eye on the accuracy of IOL power calculation in age-related cataractous patients. Methods A non-randomized controlled clinical study was performed. Two hundred and sixteen eyes of 216 cataract patients were enrolled in Yanbian Eye Ear Nose and Throat Hospital from May 2013 to February 2014. The visual acuity, intraocular pressure, break up time of tear film （BUT） , Schirmer I test （S I t） and corneal fluorescein staining were examined in all the eyes,and then the patients were assigned to mild dry eye group （73 eyes） , severe dry eye group （68 eyes） and non-dry eye control group （75 eyes）. The axial length （AL） and anterior chamber depth （ACD） were measured using IOL Master for the calculation of IOL power and K value （ corneal curvature）. Phacoemulsification with IOL implantation was performed on all the eyes,and the refractive power was measured with KR 8100 automatic optometry 2 months after operation. The mean absolute refractive error （MARE） between actual refraction and predicted refraction was calculated, and percentage of eyes in different refractive error ranges was compared between the dry eye group and non-dry eye control group. The correlations of dry eye-related parameters with peroperative K value and refractive error were analyzed. This study was approved by the Ethics of Yanbian University,and written informed consent was obtained from each subject prior to entering the cohort. Results No significant differences were found in age,gender,AL, ACD and MARE among the mild dry eye group, severe dry eye group and non-dry eye control group （all at P〉0.05 ） , and significant differences in BUT,S I t and corneal fluorescein staining scores were found among these three groups （F= 5. 460, 4. 521,3. 572, all at P〈0.05 ）. The K values were （43.59± 1.39 ） , （44.66±1.53 ） and （43.42± 1.32） D in the mild dry eye group,severe dry eye group and non-dry eye control group, and the K value in the severe dry eye group was significantly higher than that in the non-dry eye control group （P = 0. 012）. The percentage of eyes with ＋0. 50- ＋0.75 D deviation was significantly elevated（28, 8% versus 13.3 % ） , and that with -0. 50--0. 75 D deviation was significantly declined （ 17.3% versus 28.0% ） in the dry eye group compared with non-dry eye control group （X2 = 4.513, P = 0. 032 ;X2 = 4. 236, P = 0. 037 ）. A negative correlation was found between BUT and K value （ r = -0. 204, P=0. 011 ）. Conclusions Dry eye affects the accuracy of the determination of IOL power. Compared with the preoperative refraction predictive value,the postoperative refraction shift toward hyperopia.