AUG 05, 2011
This study compared the prediction error in pediatric eyes using the Holladay 2 formula in the absence of preoperative refraction with the prediction error using the Holladay 1, Hoffer Q and SRK/T formulas. The authors found that the Holladay 2 had the smallest prediction error and absolute prediction error, even in the absence of preoperative refraction.
The study included 45 patients (45 eyes) younger than age 11 who underwent cataract surgery with primary in-the-bag implantation of the Acrysof SN60WF IOL (Alcon Laboratories) performed by the same surgeon. The authors calculated the prediction error as predicted minus actual refraction. They determined mean absolute error by averaging the absolute prediction error values.
After follow up of between two weeks and two months, the mean prediction error was 0.02 D, -0.21 D, 0.07 D and -0.47 D using the Holladay 2, Holladay 1, Hoffer Q and SRK/T formulas, respectively. The mean absolute prediction error was 0.68 D, 0.71 D, 0.72 D and 0.84 D, respectively. The Holladay 2 formula had the smallest prediction error for shorter eyes (< 22.0 mm). The mean difference between actual and predicted refraction was -0.05 D using Holladay 2 (P = 0.71), -0.02 D using Holladay 1 (P = 0.89), -0.12 D using Hoffer Q (P = 0.44) and 0.04 D using SRK/T (P = 0.78).
The authors say that their routine measurement of axial length using an immersion technique and study of the Holladay 2 formula makes these results different from previously published analyses of IOL formulas in pediatric patients. While seven variables are normally entered into the Holladay 2's software, the absence of preoperative refraction data, since pediatric cataracts are often too dense for retinoscopy, has limited the formula's use in children. However, the current analysis shows that the formula can be used in pediatric patients with good results despite the absence of preoperative refraction.