Pentacam Topolyzer与角膜曲率计测量角膜屈光力的比较

Comparison of corneal power measurements with Pentacam, Topolyzer and keratometry

目的比较Seheimpflug原理摄像系统Pentacam与Placido盘成像Topolyzer角膜地形图及Topcon自动式角膜曲率计测量角膜屈光力的差异，分析三者的一致性，为临床使用提供依据。方法随机选取拟行角膜屈光手术角膜形态正常的患者39例（39只眼）。术前分别采用Pentacam、Topolyzer及Topcon自动式角膜曲率计测量角膜屈光力，并对测量结果进行统计分析。结果Topcon自动式角膜曲率计测量值为（43．35±1．36）D，Topolyzer测量值为（43．41±1．35）D；Pentacam测量所得simK、truenetpower（TNK）、4．0mmHolladay equivalent K—reading（EKR）、4．5mm EKR分别为（43．40±1．34）D，（42．14±1．25）D，（43．44±1.31）D，（43．50±1．32）D。Pentacam测量所得simK、4．0mmEKR与Topolyzer测量所得simK差异无统计学意义（P〉0．05）；其余各组K值之间比较差异均有统计学意义（P〈0．01）。三种测量方法所得K值两两之间均存在高度正相关（r〉0.90，P〈0．01）。TNK比其余各种K值均明显小（-1．21--1．36）D，一致性较差；其余各组K值之间一致性较好，95％一致性界限较窄。结论对于角膜形态正常的患者，Pentacam测量所得simK及4．0mm EKR与Topcon自动式角膜曲率计测量所得Km及Topolyzer测量所得simK具有良好的一致性，不过在临床中互相替代使用仍需要慎重。true net power比其余各种K值均明显小，不能用于人工晶状体屈光度计算。

Objective To compare corneal power measurements obtained with the Pentacam Scheimpflug analyzer, a Placido-based corneal topography （Topolyzer）, and automated Keratometry （Topcon）. Methods Thirty nine eyes with virgin corneas from 39 patients prior to laser in situ keratomileusis （LASIK） surgery were selected for the study. Corneal power measurements were obtained by Pentacam, Topolyzer and Topcon. Results The mean Km was （43.35±1.36）D by Topcon, and the mean Simulated K was （43.41±1.35）D by Topolyzer. The mean sim K, TNK and equivalent K at 4.0mm, 4.5mm corneal diameters by the Pentacam were （43.40±1.34）D,（42.14±1.25）D,（43.44 ± 1.31）D, （43.50 ±1.32）D, respectively. There were no statistically significant difference in the simK, 4.0mm EKR measured by the Pentacam and Topolyzer, respectively （P 〉0.05）. However, statistically significant differences presented in all other keratometry values （P 〈0.01）. A Pearson correlation revealed a high correlation for corneal power measurements among the three devices （r 〉0.9 for all, P 〈0,01 for all）. It showed well agreement with the Altman plots among the three measurements and the 95% LoA was narrow. A poorer agreement was displayed in the mean true net power, which showed a lower using pentacam, corneal sured by the Pentacam with cautiously. Corneal other keratometry values keratometry values. Conclusions A similar keratometry values revealed by topography and the automated Keratometry. The simK and 4.0ram EKR mea- might be used to replace the K values measured by the other two devices power values calculated by the true net power are significantly lower than and can not be entered into intraocular lens power formulas.