Accuracy of intraocular lens formulas using a sum-of-segments axial length biometer in an Asian population

Objectives To compare biometric measurements obtained using two optical biometers, the Argos and the IOLMaster 700, and to evaluate the accuracy of intraocular lens (IOL) power calculation formulas based on Argos measurements in an Asian population. Methods Pre-operative biometric data acquired using both the Argos and IOLMaster 700 biometers in patients undergoing cataract surgery were analyzed. Post-operative prediction error was calculated by subtracting the predicted refraction generated by each IOL formula, based on Argos-derived biometric data, from the actual manifest refraction measured 1 month after surgery. Both traditional and modern IOL formulas were evaluated, including formulas specifically designed for sum-of-segment axial length (AL) measurements, such as the Barrett True Axial Length and EVO 2.0 formulas. Subgroup analyses were performed for short eyes with AL 26 mm. Results A total of 215 eyes from 215 patients were included. Compared with measurements obtained using the IOLMaster 700, AL and white-to-white distance measured by the Argos were lower, whereas anterior chamber depth and mean keratometry values were significantly higher. AL measurements differed significantly between the two biometers in both short and long eyes. Most IOL power calculation formulas demonstrated good performance when using Argos measurements, including in eyes with short and long ALs. On linear regression analysis, the EVO and Holladay I formulas showed no statistically significant AL-dependent bias in prediction error. Conclusion IOL power calculation formulas demonstrate good performance when applied to sum-of-segment AL measurements obtained using the Argos biometer. Overall, formulas specifically designed for sum-of-segment AL measurements yielded the best predictive accuracy.