A COMPARATIVE STUDY ON ACCURACY OF DIFFERENT INTRAOCULAR LENS POWER CALCULATION FORMULAS IN VARIOUS AXIAL LENGTH SUBSETS

Abstract

Purpose: To nd the most accurate IOL power calculation formula in predicting the post-operative refractive error in various axial length subsets by comparing four formulas viz SRK II, SRK/T, Holladay 1 and Hoffer Q. A prospective, com Materials and Methods: parative study was conducted at Gandhi Medical College and Hospital and Sarojini Devi Eye Hospital. Study group consisted of subjects undergoing phacoemulsication with intraocular lens implantation. IOL powers were calculated for each group with SRK II, SRK/T, Hoffer Q and Holladay I. The predicted postoperative spherical equivalent (PSE) for the chosen IOL power was noted for each formula. The predictive accuracy of each formula in each group was analyzed by comparing the difference between the actual postoperatively measured Spherical Equivalent (SE) and the preoperatively Predicted Spherical Equivalent (PSE) as Estimation Error (E). The absolute error (AE) was dened as the absolute value of E. Results: 130 eyes were included in the study which were divided into 3 groups. The mean Absolute Error (±SD) for SRK II, SRK/T, Holladay 1 and Hoffer Q was 0.87 ± 0.69, 0.96 ± 0.79, 1.1 ± 0.88 and 1.18 ± 0.94, respectively. The Hoffer Q formula had statistically signicant higher mean Absolute Error in comparison to SRK II (p < 0.02). There was no statistically signicant difference in mean Absolute Error of SRK II, SRK/T and Holladay 1. SRK II, SRK/T, Holladay 1 and Hoffer Q were equally accurate in pre Conclusion: dicting the postoperative refraction group A and group C. Hoffer Q was the least accurate in group B.