Comparison of Manual and Automated Keratometric Measurements of the Anterior Corneal Curvature (ACC) and Refractive Power

Abstract

The study compared the measurement of the Anterior Corneal Curvature (ACC) and refractive power using manual (Bausch and Lomb) and automated (GRK 2100) keratometers among healthy participants. The ACCs of 100 eyes of 50 healthy participants, aged 16 33 years, were measured using the manual (Bausch and Lomb) and automated (GRK 2100) keratometers. Data were analyzed using MathWorks MATLAB version R2024a (MathWorks, Inc., MA, USA). The 95% limits of agreement were evaluated with the Bland Altman plot The curvature plots of horizontal and vertical measurements showed tight clustering of data points around the zero bias line (red dashed line), with 95% limits of agreement (green dashed lines) confined within ±0.10 to ±0.15 mm. The narrow range indicates strong consistency between the two techniques. The horizontal and vertical power plots showed a broader spread of differences, with limits of agreement extending to approximately ±1.0 D and one data point in each plot exceeding ±2.0 D. Despite the wide range, the majority of the points remained within the limits, and the mean difference remained centered close to zero. Overall, automated and manual keratometry showed stronger agreement for curvature plots than power plots.