准分子激光角膜屈光手术后角膜厚度改变对近视眼眼压读数的影响

Intraocular pressure changes in myopia caused by corneal thickness ablation after corneal refractive surgery

目的 评价准分子激光角膜屈光手术对低中度和高度近视眼压测量的不同影响,探讨角膜屈光术后眼压计读数的“正常值”。方法 38例72眼近视眼患者分为低中度近视和高度近视2组,分别于术前、术后测量眼压、角膜中央厚度和角膜前表面屈光力,并比较2组眼压计读数改变的差异及其与角膜中央厚度及角膜前表面屈光力的关系。所有数据用配对t检验和相关与回归分析进行统计学处理。结果 低中度组和高度组术前眼压值分别为15.19±2.89mmHg(1mmHg=0.133kPa)和16.32±2.54mmHg,术后为10.16±2.17mmHg和10.17±2.61mmHg,二者眼压值差异无统计学意义(P>0.05);2组术前、术后眼压计读数下降值分别为5.02±2.10mmHg和6.15±1.96mmHg;术后2组残留角膜中央厚度分别为445—557μm和490±30μm,差异均无统计学显著性意义(P>0.05);术后角膜前表面屈光力分别为39.18±1.60D和37.56±1.61D,差异显著,有统计学意义(P=0.001)。眼压计读数改变只在低中度组与角膜中央厚度有依存关系,其回归方程为:术后眼压计读数=-3.207+2.667×术后角膜中央厚度。结论 在一定范围内,准分子激光角膜屈光术后眼压计读数随角膜中央厚度的减少而降低;角膜中央厚度的改变是影响眼压测量准确性的主要因素;术后残留的角膜中央厚度相同。

Aim To evaluate different effects of corneal refractive surgery by excimer laser on intraocular pressure (10P) in low-middle and high myopia and to disuss the normal value of iop reading after the surgery. Methods All of the 72 eyes of 38 cases were divided into two groups: low-middle and high myopia. IOP, central corneal thickness (CCT)and anterior corneal power (ACP) were measured before and after corneal refractive surgery. The change in IOP readings, and its relationship with CCT and ACP were studied. All of the data were analyzed byT test and correlation-regression analysis. Results IOP reading in the two groups was 15.19±2.89mmHg and 16.32±2.54mmHg before surgery, 10.16±2.17mmHg and 10.17±2.61mmHg after surgery respectively. The reduction in IOP reading in the 2 groups was 5.02±2. 10mmHg and 6.15±1.96mmHg respectively. There was no statistic difference in IOP readings between the two groups either before or after the corneal refractive surgery (P>0.05), or in the residual CCT postoperatively between the 2 groups. Significant statistic difference in ACP between the two groups was found postoperatively (P<0.01). Correlation between the changes of IOP reading and CCT was found in low-middle group and the regression equation was: postoperative IOP reading = -3.207+ 2.667× postoperative CCT. Conclusion Within a range, IOP after the corneal refractive surgery decreases with CCT decline; CCT change is the major factor affecting the accuracy of IOP measurement; if residual CCT is similar, the IOP reading is similar. The 'normal value' range (95%) after the corneal refractive surgery is 6.38-14.90mmHg.