高度近视并发性白内障患者术前角膜 后表面散光特征

目的：分析高度近视并发性白内障患者术前角膜后表面散光（PA）的特征。方法：系列病例研究。收 集2018年1-6月期间就诊于山西省眼科医院的白内障患者215例（215眼），按照眼轴长度（AL）分为 高度近视组（AL≥26 mm）和对照组（20 mm≤AL＜26 mm）。其中高度近视组94例（94眼），对照组 121例（121眼），术前行Pentacam检查，分析PA、总角膜散光（TA）、模拟角膜散光（KA）的分布特点 及相关性，采用算术法和矢量法分析TA与KA的差异。2组间计量资料比较采用独立样本t检验，角 膜后表面散光的相关性分析采用Pearson相关分析。结果：高度近视组PA为（-0.33±0.20）D，其中 79.6%为逆规散光，大于0.5 D的患眼占30.8%，对照组PA为（-0.31±0.18）D，2组之间差异无统计学 意义（t=0.589，P=0.557）。高度近视组KA与TA的矢量误差为（0.12±0.21）D@4°，其中24.5%患眼二 者之间误差≥0.5 D。PA与KA、Km（KA）、Km（PA）之间呈正相关性（r=0.340，P=0.001；r=0.285， P=0.006；r=0.333，P=0.001），对于KA＞0.5 D患者，KA和PA轴位差值与TA和KA差值之间呈正相 关性（r=0.235，P=0.004）。结论：高度近视组角膜后表面散光分布与对照组之间差异无统计学意义。 高度近视组忽略PA同样会导致TA计算误差，对植入Toric人工晶状体的患者应考虑输入个性化PA值。

Characteristics of Posterior Corneal Astigmatism in Cataract Patients with High Myopia

Objective: To evaluate the characteristics of posterior corneal astigmatism (PA) in cataract patients with high myopia. Methods: In this series of case study, 215 eyes of 215 patients from Shanxi Eye Hospital were recruited from January to June 2018 and divided into a high myopia group (94 patients, 94 eyes) and a control group (121 patients, 121 eyes). PA, total corneal astigmatism (TA) and simulated keratometric astigmatism (KA) were measured by arotating Scheimplfulg camera (Pentacam HR). The error produced by TA using KA was calculated with vector and arithmetical analysis. Data were analyzed by t test and correlation analysis Results: In the high myopia group, the mean magnitude of the pa was -0.33±0.20 D, and exceeded 0.5 D in 30.8%. The steepest meridian was vertically aligned in 79.6% of the cases. In thecontrol group, the mean magnitude of the PA was -0.31±0.18 D. There was no significant difference in PA between the high myopia group and the control group (t=0.589, P=0.557). In the high myopia group, the vector error between KA and TA was (0.12±0.21) D@4°. There was a correlation between the magnitude of PA and KA, PA and Km (KA), and PA and Km (PA) (r=0.340, P=0.001; r=0.285, P=0.006; r=0.333, P=0.001). For KA>0.5 D patients, the difference in magnitude between ta and Ka significantly increased with an increase in the magnitude of pa（r=0.235, P=0.004). Conclusion: There was no significant difference in PA between the high myopia group and the control group. In the high myopia group, neglecting PA may lead to an incorrect estimate of ta. Personalized PA should be considered in patients with Toric intraocular lens implants.