Accuracy of Modified Axial Length Adjustment for Intraocular Lens Power Calculation in Chinese Axial Myopic Eyes

Abstract

Purpose: To evaluate the accuracy of modified Wang-Koch adjustment for intraocular lens power calculation in axial myopic eyes at Zhongshan Ophthalmic Center, Guangzhou, China.

Materials and methods: Consecutive cataract patients with axial lengths (ALs) over 25.0 mm were enrolled. The accuracies of SRK/T and Holladay 1 with modified Wang-Koch AL adjustment were compared with those calculated with optimized lens constants for long eyes and lens constants from the User Group for Laser Interference Biometry. They were also compared with Barrett Universal II (Barrett) and Haigis. The median absolute error (AE), mean absolute error (MAE) and proportions of eyes with a prediction error (PE) within ±0.25 diopter (D), ± 0.50 D and ± 1.00 D were determined.

Results: In total, 325 eyes from patients with a mean age of 58.62 ± 13.51 years and a mean preoperative AL of 27.65 ± 2.05 mm were included. For SRK/T, Wang-Koch adjustment did not increase the proportion of eyes within the given diopter of PE in any AL subgroup and led to worse outcomes for ALs between 27.0 mm and 30.0 mm (n = 129; P = .001) compared to the method of using measured AL and optimized constant. For Holladay 1, comparison of PEs within ±0.50 D favored AL adjusted eyes in all subgroups. Moreover, the median AE of Holladay 1 with Wang-Koch adjustment in eyes with ALs between 25.0 mm and 27.0 mm was lower than that of Barrett (n = 146; P = .02).

Conclusions: The modified Wang-Koch adjustment had better performance than constant optimization for Holladay 1 but not for SRK/T. Holladay 1 with Wang-Koch adjustment was more accurate than Barrett for ALs between 25.0 mm and 27.0 mm.

Keywords: Intraocular lens power calculation; axial length adjustment; cataract; myopia; prediction error.