Accuracy of formulae for secondary intraocular lens power calculations in pediatric aphakia

Purpose: To compare the accuracy of axial length vergence formulas versus refractive vergence formulas for secondary intraocular lens (IOL) implantation in pediatric aphakia. Methods: This retrospective comparative study, evaluated 31 eyes of 31 patients aged 3.5 years, who had undergone secondary IOL implantation. The median absolute error (MedAE) was compared between axial length vergence formulas (Hoffer Q, Holladay I, SRK II, and SRK/ T) and refractive vergence formulas (Lanchulev, Holladay R, Mackool, and Khan) as well as between formulas within the same vergence. Results: There was a significant difference (P ¼ 0.010) between MedAE for axial length vergence formulas [1.19 Diopter(D)] and MedAE for refractive vergence formulas (2.48 D). The MedAE of axial length vergence formulas were comparable as to Hoffer (1.59 D), Holladay (1.27 D), SRK/T (1.23 D), and SRK II (1.30 D). Among refractive vergence formulas, Lanchulev (5.00 D) and Holladay R (2.51 D) had significantly larger MedAE as compared to Khan (2.06 D) and Mackool (2.15 D). Conclusion: Axial length vergence formulas performed significantly better than refractive vergence formulas; however, axial length vergence formulas were comparable within the same vergence.