Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel.
Department of Ophthalmology, Rambam Health Care Campus, Haifa, Israel.
Graefes Arch Clin Exp Ophthalmol. 2021 Nov;259(11):3477-3483. doi: 10.1007/s00417-021-05237-6. Epub 2021 Jun 7.
To identify factors associated with changes in the posterior cornea curvature following laser refractive surgery.
This retrospective study included myopic astigmatic eyes that underwent PRK between January 2013 and December 2013 at Care-Vision Laser Centers, Tel-Aviv, Israel. The average posterior K was measured with the Sirius device at a radius of 3 mm from the center. The correlations between the surgical induced change in average posterior k and preoperative parameters such as central corneal thickness (CCT), refraction, Baiocchi Calossi Versaci index (BCV), ablation depth, percent tissue altered (PTA), and residual stroma bed (RSB) were analyzed.
A total of 280 eyes with a mean age of 24.9 ± 6.1 years (range, 18-47 years were included in this study. The mean PTA was 14.8 ± 6.0%. A greater change in posterior K was found in females (p = 0.01), smaller treatment zones of 6.0 mm (p = 0.02) and PTA > 20% (p < 0.001). A lower CCT (r = - 0.24, p < 0.001), higher myopia (r = - 0.34, p < 0.001), higher astigmatism (r = - 0.17, p < 0.001), higher total BCV (r = 0.13, p = 0.03), lower back BCV (r = - 0.12, p = 0.05), higher front BCV (r = 0.16, p = 0.01), higher posterior I-S ratio (r = 0.16, p = 0.01), and a lower RSB (r = - 0.42, p < 0.001) were all significantly correlated with percentage of change in mean posterior K. In ranked stepwise multiple regression analysis, 26.2% of the variance of change in posterior K could be explained by the examined factors. The factors that remained significant were PTA (p < 0.001), CCT (p = 0.001), and posterior I-S ratio (p = 0.001). PTA alone accounted for 15% of the variance in posterior K changes in multivariate analysis.
Understanding of factors affecting a change in posterior cornea after refractive surgery may have an important practical value for the prevention of iatrogenic keratectasia. Preoperative CCT, posterior I-S ratio, and PTA were significantly associated with changes in posterior K after PRK. PTA was the strongest predictor of posterior corneal changes (p < 0.001).
确定与激光屈光手术后后角膜曲率变化相关的因素。
这项回顾性研究纳入了 2013 年 1 月至 2013 年 12 月期间在以色列特拉维夫的 Care-Vision Laser Centers 接受 PRK 的近视散光眼。使用 Sirius 设备在距离中心 3 毫米处测量平均后 K 值。分析了手术引起的平均后 k 值变化与术前参数（如中央角膜厚度 (CCT)、屈光度、Baiocchi Calossi Versaci 指数 (BCV)、消融深度、组织改变百分比 (PTA) 和剩余基质床 (RSB)）之间的相关性。
本研究共纳入 280 只眼，平均年龄为 24.9±6.1 岁（范围 18-47 岁）。平均 PTA 为 14.8±6.0%。女性的后 K 变化更大（p=0.01），治疗区较小（6.0 毫米）（p=0.02），PTA>20%（p<0.001）。较低的 CCT（r=−0.24，p<0.001）、较高的近视（r=−0.34，p<0.001）、较高的散光（r=−0.17，p<0.001）、较高的总 BCV（r=0.13，p=0.03）、较低的后 BCV（r=−0.12，p=0.05）、较高的前 BCV（r=0.16，p=0.01）、较高的后 I-S 比（r=0.16，p=0.01）和较低的 RSB（r=−0.42，p<0.001）与平均后 K 变化的百分比均呈显著相关。在分级逐步多元回归分析中，后 K 变化的 26.2%可由检查因素解释。在多元分析中，仍然具有统计学意义的因素是 PTA（p<0.001）、CCT（p=0.001）和后 I-S 比（p=0.001）。PTA 单独解释了后 K 变化的 15%。
了解屈光手术后后角膜变化的相关因素对于预防医源性角膜扩张具有重要的实际价值。术前 CCT、后 I-S 比和 PTA 与 PRK 后后 K 变化显著相关。PTA 是后角膜变化的最强预测因子（p<0.001）。
