三种IOL计算公式预测超高度近视白内障患者术后屈光度的准确性比较

目的：评估应用Pentacam AXL全景生物测量仪3 种人工晶状体（IOL）计算公式（SRK/T、Haigis和 Barrett Universal Ⅱ）预测超高度近视白内障患者术后屈光度的准确性。方法：前瞻性临床研究。选取2017 年10 月至2018 年3 月于重庆医科大学附属第一医院眼科行白内障手术的超高度近视[眼轴长度（AL）≥28 mm]白内障患者，应用Pentacam AXL全景生物测量仪进行角膜前后表面曲率、眼轴长度、前房深度等数据测量，个性化选择适宜的预留屈光度IOL，获取3 个公式理论预留屈光度，术 后3 个月随访时测量患者实际屈光状态，计算各个公式理论预留屈光度与术后实际屈光度的差值即平均屈光误差、差值的绝对值即平均绝对屈光误差（MAE）。非正态分布定量资料数据分析采用Mann-Whitney U或卡方检验；用线性回归分析评价眼轴与平均绝对屈光误差的相关性。结果：共32例（56 眼）患者纳入研究，SRK/T、Haigis和Barrett Universal Ⅱ公式平均屈光误差分别为-0.18（-0.53，0.23）、-0.18（-0.54，0.09）、-0.11（-0.49，0.15），MAE分别为0.40（0.20，0.61）、0.32（0.14，0.64）、0.27（0.12，0.55）。对于平均屈光误差，Barrett Universal Ⅱ与SRK/T公式对比，差异有统计学意义（Z=-2.517，P=0.012）；Barrett Universal Ⅱ与Haigis公式、Haigis与SRK/T公式相比，差异无统计学意义（P>0.05）；而对于MAE，Barrett Universal Ⅱ、Haigis与SRK/T公式间差异均无统计学意义（P>0.05）。 针对3 种IOL计算公式，MAE与AL均相关，对于SRK/T公式，AL增加1 mm，MAE增加0.23 D；在Haigis公式中，AL增加1 mm，MAE增加0.04 D；但是在Barrett Universal Ⅱ公式中，AL增加1 mm，MAE反而会减少0.01 D。结论：3 种IOL计算公式对超高度近视白内障患者IOL度数的预测都是相对准确的，其中Barrett Universal Ⅱ公式更具优势。

Comparison of Prediction Accuracy of Three Intraocular Lens Calculation Formulas for Postoperative Refractive Power in Cataract Patients with Ultra-High Myopia

Objective: To evaluate the prediction accuracy of three intraocular lens power calculation formulas (SRK/T, Haigis and Barrett Universal Ⅱ) for postoperative refractive power using a Pentacam AXL panoramicbiometer in cataract patients with ultra-high myopia. Methods: This was a prospective clinical study. Thirty-two cataract patients (56 eyes) with ultra-high myopia [axial length (AL) ≥28 mm] who underwent cataract surgery in the Ophthalmology Department of the First Affiliated Hospital of Chongqing Medical University from October 2017 to March 2018 were selected. The Pentacam AXL panoramic biometer was used to measure the anterior and posterior corneal surface curvature, anterior chamber depth and AL. An intraocular lens (IOL) with appropriate residual refractive power was individually selected for each eye, and the postoperative residual refractive powers of the three formulas were obtained. The refractive powers of the patients at three months after surgery were measured. Then the difference between the preoperative residual refractive power and postoperative refractive power, which was called the mean refractive error, the absolute value of the difference, which was called the mean absolute refractive error (MAE), were calculated. The quantitative data of non-normal distributions were expressed by the median and percentile (P25, P75), and the measurement data were tested by a Mann-Whitney U test or chi-square test. Linear regression analysis was used to evaluate the correlation between AL and MAE. Results: The median and percentile (P25, P75) of the mean refractive errors of the SRK/T, Haigis and Barrett Universal Ⅱ formula were -0.18(-0.53, 0.23), -0.18(-0.54, 0.09), -0.11(-0.49, 0.15), respectively. The mean refractive error of the Barrett Universal Ⅱ formula was significantly lower than that of SRK/T formula (Z=-2.517, P=0.012). However, the Barrett Universal Ⅱ formula agreed with the Haigis formula, the Haigis formula agreed with the SRK/T formula, and the differences in mean refractive error were not statistically significance (P>0.05). The median and percentile (P25, P75) of MAE of the SRK/T, Haigis and Barrett Universal Ⅱ formulas were 0.40(0.20, 0.61), 0.32(0.14, 0.64), 0.27(0.12, 0.55), respectively. And there were no significant differences among the Barrett Universal Ⅱ, Haigis and SRK/T formulas (P>0.05). Moreover, the MAE is related to AL. In the SRK/T formula, an increase of 1 mm in axial length led to an increase of 0.23 D in MAE; in the Haigis formula, an axial length increase by 1 mm led to a MAE increase of 0.04 D; but in the Barrett Universal Ⅱ formula, an axial length increase of 1 mm led to an absolute error reduction of 0.01 D. Conclusions: The three IOL power calculation formulas are relatively accurate for postoperative refractive error in cataract patients with ultra-high myopia. The Barrett Universal Ⅱ formula has more advantages than the SRK/T formula and Haigis formula.