Accuracy of Intraocular Lens Calculation Formulas for the Four-Flanged Fixation Technique in Eyes With No Capsular Support.

To assess the refractive prediction error of four intraocular lens (IOL) calculation formulas in eyes that have undergone scleral fixation using the four-flanged technique. This was a retrospective cohort analysis of patients who underwent scleral fixation using the four-flanged technique at the Shamir Medical Center between 2020 and 2021. Refractive prediction errors for four IOL prediction formulas (Barrett Universal II, Holladay 1, SRK/T, and Kane) were obtained by subtracting the predicted spherical equivalent from the postoperative spherical equivalent. Mean arithmetic refractive prediction error and mean absolute error were calculated and compared. Twenty-three eyes of 23 patients were included in the analysis. The Akreos AO60 IOL (Bausch & Lomb, Inc) was implanted in 9 eyes and the BunnyLens HP IOL (Hanita Lenses) in 14 eyes. Mean age was 72.84 ± 13.2 years. All formulas produced myopic mean arithmetic refractive prediction error. Mean arithmetic refractive error and mean absolute error were equal in absolute number. Mean arithmetic refractive prediction errors were -0.72 diopters (D) for Barrett Universal II, -0.61 D for Holladay 1, -0.77 D for SRK/T, and -0.94 D for Kane formulas. The refractive outcome differed significantly from the predicted refraction in all formulas. There were no statistically significant differences in prediction errors between the formulas. Refractive outcomes of the four-flanged fixation technique produced myopic results compared to the predicted refraction for all formulas tested. This suggests that the effective lens position is more anterior than in-the-bag IOL implantation.