From the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University (M.Z., Z.L., S.L., X.Z., D.Z., G.J.), Guangzhou, Guangdong, China.
Albany Medical College (C.A.Y.), Albany, New York, USA.
Am J Ophthalmol. 2023 Aug;252:121-129. doi: 10.1016/j.ajo.2023.03.021. Epub 2023 Mar 25.
To introduce a method of predicting effective lens position (ELP) among congenital ectopia lentis (CEL) patients undergoing transscleral fixation of intraocular lens (IOL), and evaluate its effect on improving refractive outcome by utilizing the Sanders-Retzlaff-Kraff / theoretical (SRK/T) formula.
Retrospective cross-sectional study.
A training set (93 eyes) and validation set (25 eyes) was included. Z value as the distance between the iris plane and a hypothetic postoperative IOL position was introduced in this study. The Z-modified ELP consisted of corneal height (Ch) and Z (ELP = Ch + Z), and Ch was calculated by keratometry (Km) and white-to-white (WTW). The value of Z was identified by linear regression formula with the involvement of axial length (AL), Km, WTW, age, and gender. The comparison of mean (MAE) and mediate absolute error (MedAE) among Z-modified SRK/T formula, SRK/T, Holladay I, and Hoffer Q formula was performed to evaluate the performance of Z-modified SRK/T formula.
Z value was associated with AL, K, WTW, and age (Z = offset + 15.1093 × lg (AL) + 0.0953899 × Km - 0.3910268 × WTW + 0.0164197 × Age - 19.34804). The Z-modified ELP has good accuracy with no difference to back-calculated ELP. The accuracy of Z-modified SRK/T formula was better than other formulas (P < .001) as the MAE was 0.24 ± 0.19 diopter (D) and MedAE was 0.22 D (95% CI: 0.01-0.57 D). Sixty-four percent of eyes had a refractive error smaller than ±0.25 D, and none of the subjects had a prediction error greater than ±0.75 D.
ELP of CEL can be accurately predicted by AL, Km, WTW, and age. Z-modified SRK/T formula improved on the current formula by improving predicting accuracy of ELP and may serve as a promising formula for CEL patients with transscleral fixation of IOL.
介绍一种预测先天性晶状体异位（CEL）患者经巩膜固定人工晶状体（IOL）后有效晶状体位置（ELP）的方法，并利用桑德斯-雷茨拉夫-克拉夫/理论（SRK/T）公式评估其改善屈光结果的效果。
回顾性横断面研究。
纳入训练集（93 只眼）和验证集（25 只眼）。本研究引入了虹膜平面与假想术后 IOL 位置之间的距离 Z 值作为指标。Z 修正后的 ELP 由角膜高度（Ch）和 Z 组成（ELP=Ch+Z），Ch 通过角膜曲率计（Km）和白到白（WTW）计算。Z 值通过包含眼轴（AL）、Km、WTW、年龄和性别在内的线性回归公式确定。通过比较 Z 修正后的 SRK/T 公式、SRK/T、Holladay I 和 Hoffer Q 公式的平均绝对误差（MAE）和中位数绝对误差（MedAE）来评估 Z 修正后的 SRK/T 公式的性能。
Z 值与 AL、K、WTW 和年龄相关（Z=偏移量+15.1093×lg（AL）+0.0953899×Km-0.3910268×WTW+0.0164197×年龄-19.34804）。Z 修正后的 ELP 具有良好的准确性，与反算 ELP 无差异。Z 修正后的 SRK/T 公式的准确性优于其他公式（P<.001），MAE 为 0.24±0.19 屈光度（D），MedAE 为 0.22 D（95%CI：0.01-0.57 D）。64%的眼屈光误差小于±0.25 D，无预测误差大于±0.75 D。
通过 AL、Km、WTW 和年龄，可以准确预测 CEL 的 ELP。Z 修正后的 SRK/T 公式通过提高 ELP 的预测准确性，改善了现有公式，可为经巩膜固定 IOL 的 CEL 患者提供一种有前途的公式。
