Comparative Evaluation of Intraocular Lens Power Calculation Formulas in Children

Introduction With the advent of newer microsurgical techniques, the results for cataract surgery have become quite promising. An accurate intraocular lens (IOL) power calculation is one of the most important factors in optimizing the results. The aim of this study was to evaluate the accuracy of four IOL power calculation formulas, namely, Barrett Universal II, Holladay 1, SRK/T and Hoffer Q, using optical biometry in children undergoing cataract surgery with primary IOL implantation. Methods This was a cross-sectional study. A total of 60 eyes of 42 children aged 5-16 years with congenital cataract and having undergone uneventful cataract surgery with IOL implantation were included in the study. Eyes were divided into three groups based on the axial length (AL): short (AL <22.00 mm), medium (AL 22-24.50 mm) and medium long (AL 24.50-26.00 mm). Optical biometry was used and the IOL power was calculated using the Barrett Universal II formula. The predicted postoperative refraction with the other three formulas, namely, SRK/T, Holladay 1 and Hoffer Q, using the same IOL power was estimated. This was compared with the actual postoperative refraction (spherical equivalent at 12 weeks) to give the absolute prediction error. The mean of all absolute prediction errors gave the mean absolute prediction error (MAE) values for each formula that were then compared. Results The MAE was 0.64 ± 0.73 for Barrett Universal II, 0.7 ± 0.72 for Holladay 1, 0.71 ± 0.65 for Hoffer Q and 0.8 ± 0.75 for SRK/T. Thus, Barrett Universal II had the lowest MAE across the whole group. The difference in the MAEs was not statistically significant. Conclusion Barrett Universal II had the lowest MAE and thus was predictable for the highest number of eyes in our study, although this was not statistically significant (p=0.176).