Xu Ke, Qi Hong, Peng Rongmei, Xiao Gege, Hong Jing, Hao Yansheng, Ma Boping
Department of Ophthalmology, Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing, 100191, People's Republic of China.
BMC Ophthalmol. 2018 Oct 17;18(1):268. doi: 10.1186/s12886-018-0931-y.
To compare different K readings in pseudophakic patients post-Descemet's stripping automated endothelial keratoplasty (DSAEK) and evaluate corresponding prediction errors in intraocular lens (IOL) power calculations.
Subjects that underwent cataract surgery and DSAEK surgery at least 3 and 6 months prior, respectively, and IOL implantation in the capsular bag were included in this study. Manifest refraction and IOL information were recorded. A Scheimpflug keratometer (Pentacam) was used for corneal measurements, including the mean anterior and posterior radii of curvature, simulated keratometer (SimK), true net power (TNP), and equivalent K reading (EKR) at the 4.0-mm zone. Conventional keratometry was acquired using the IOLMaster (K). The four K measurements were evaluated for calculating the predicted refraction.
The study included 20 eyes from 19 subjects. The ratio of the posterior to the anterior corneal radius was 74.1 ± 3.24%. Comparison of the four keratometric methods (K, SimK, EKR, and TNP) revealed statistically significant differences among all the methods besides K and SimK. Of the four IOL calculation methods(K, SimK, EKR and TNP method),the arithmetic prediction error of the K, SimK, and EKR methods featured nonsignificant differences from zero(p = 0.07, 0.19 and 0.84 respectively); the EKR method calculated the highest percentage of eyes with IOLs within the prediction error.
IOL calculations in post-DSAEK eyes using K, SimK, and EKR can yield small refractive errors after surgery. The EKR (4.0-mm diameter) method was found to be the most accurate.
比较接受后弹力层剥除自动内皮角膜移植术（DSAEK）的人工晶状体眼的不同K值读数，并评估人工晶状体（IOL）屈光度计算中的相应预测误差。
本研究纳入了分别在至少3个月和6个月前接受白内障手术和DSAEK手术，并在囊袋内植入IOL的受试者。记录了显验光和IOL信息。使用眼前节分析系统（Pentacam）进行角膜测量，包括平均前后曲率半径、模拟角膜曲率计读数（SimK）、真实净度数（TNP）以及4.0mm区域的等效K值读数（EKR）。使用IOLMaster获取传统角膜曲率计读数（K）。评估这四种K值测量方法用于计算预测屈光不正的情况。
该研究纳入了19名受试者的20只眼。角膜前后半径之比为74.1±3.24%。四种角膜曲率测量方法（K、SimK、EKR和TNP）的比较显示，除K和SimK外，所有方法之间均存在统计学显著差异。在四种IOL计算方法（K、SimK、EKR和TNP法）中，K、SimK和EKR法的算术预测误差与零无显著差异（p分别为0.07、0.19和0.84）；EKR法计算出的IOL在预测误差范围内的眼的百分比最高。
使用K、SimK和EKR对DSAEK术后眼进行IOL计算，术后屈光不正误差较小。发现EKR（直径4.0mm）法最为准确。
