Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
Invest Ophthalmol Vis Sci. 2018 Feb 1;59(2):1016-1024. doi: 10.1167/iovs.17-22405.
To evaluate the accuracy of IOL power calculation using adjusted corneal power according to the posterior/anterior corneal curvature radii ratio.
Nine hundred twenty-eight eyes from 928 reference subjects and 158 eyes from 158 cataract patients who underwent phacoemulsification surgery were enrolled. Adjusted corneal power of cataract patients was calculated using the fictitious refractive index that was obtained from the geometric mean posterior/anterior corneal curvature radii ratio of reference subjects and adjusted anterior and predicted posterior corneal curvature radii from conventional keratometry (K) using the posterior/anterior corneal curvature radii ratio. The median absolute error (MedAE) based on the adjusted corneal power was compared with that based on conventional K in the Haigis and SRK/T formulae.
The geometric mean posterior/anterior corneal curvature radii ratio was 0.808, and the fictitious refractive index of the cornea for a single Scheimpflug camera was 1.3275. The mean difference between adjusted corneal power and conventional K was 0.05 diopter (D). The MedAE based on adjusted corneal power (0.31 D in the Haigis formula and 0.32 D in the SRK/T formula) was significantly smaller than that based on conventional K (0.41 D and 0.40 D, respectively; P < 0.001 and P < 0.001, respectively). The percentage of eyes with refractive prediction error within ± 0.50 D calculated using adjusted corneal power (74.7%) was significantly greater than that obtained using conventional K (62.7%) in the Haigis formula (P = 0.029).
IOL power calculation using adjusted corneal power according to the posterior/anterior corneal curvature radii ratio provided more accurate refractive outcomes than calculation using conventional K.
评估根据后/前角膜曲率半径比调整角膜曲率的眼内晶状体（IOL）屈光力计算的准确性。
纳入 928 只眼（来自 928 名参照受试者）和 158 只眼（来自 158 名白内障患者），这些患者均接受了超声乳化白内障吸除术。使用参照受试者的后/前角膜曲率半径比的几何平均值以及常规角膜曲率计（K）测量的调整后的前和预测的后角膜曲率半径，计算白内障患者的调整角膜曲率。基于调整后的角膜曲率和常规 K 值，使用 Haigis 和 SRK/T 公式分别计算中位数绝对误差（MedAE）。
后/前角膜曲率半径比的几何平均值为 0.808，单个 Scheimpflug 相机的角膜虚拟折射率为 1.3275。调整后的角膜曲率与常规 K 的平均差值为 0.05 屈光度（D）。基于调整后的角膜曲率的 MedAE（Haigis 公式为 0.31 D，SRK/T 公式为 0.32 D）明显小于基于常规 K 的 MedAE（分别为 0.41 D 和 0.40 D；P < 0.001 和 P < 0.001）。使用调整后的角膜曲率计算，预测误差在±0.50 D 以内的眼的百分比（74.7%）在 Haigis 公式中明显大于使用常规 K 值（62.7%）（P = 0.029）。
根据后/前角膜曲率半径比调整角膜曲率的 IOL 屈光力计算比使用常规 K 值提供更准确的屈光结果。
