ACCURACY OF BIOMETRY USING AUTOMATED AND MANUAL KERATOMETRY FOR INTRAOCULAR LENS POWER CALCULATION: A COMPARATIVE OBSERVATIONAL STUDY

Abstract

Background: Accurate intraocular lens (IOL) power calculation is essential for achieving predictable refractive outcomes after cataract surgery. Keratometry is an important component of biometric assessment, and both manual and automated methods are used in clinical practice.

Aim: To compare the accuracy of biometry using manual and automated keratometry for IOL power calculation in patients undergoing cataract surgery.

Materials and Methods: This comparative observational study was conducted from September 2023 to October 2024 and included 156 patients. Patients were divided into a manual keratometry (MK) group and an automated keratometry (AK) group, with 78 patients in each group. Postoperative residual spherical error was assessed and compared between the groups.

Results: A postoperative residual spherical error of ±0.50 D was observed in 64 patients (82.05%) in the MK group and 69 patients (88.46%) in the AK group. Residual error >±0.50 to ±1.50 D occurred in 14 patients (17.95%) and 9 patients (11.54%), respectively. No patient in either group had residual spherical error >±1.50 D. Mean postoperative spherical error was 0.27 ± 0.38 D in the MK group and 0.17 ± 0.36 D in the AK group. The difference was not statistically significant (t=1.077, df=154, P=0.283).

Conclusion: Automated keratometry showed a slightly higher proportion of patients achieving a postoperative residual spherical error within ±0.50 D than manual keratometry; however, the difference in mean spherical error was not statistically significant. Automated keratometry may therefore provide clinically comparable refractive accuracy to manual keratometry for routine IOL power calculation.