A study regarding efficacy of various intraocular lens power calculation formulas in a subset of Indian myopic population

Efficacy of intraocular lens power calculation formulas in a subset of Indian myopic population. Retrospectively reviewed 43 patients who underwent phacoemulsification with high axial length (AL) (>24.5 mm, range 24.75-32.35 mm). The power of the implanted intraocular lens (IOL) was used to calculate the predicted post-operative refractive error by four formulas: Sanders-Retzlaff-Kraff (SRK II), SRK/T, Holladay 1, and Hoffer Q. The predictive accuracy of the formulas was analyzed by comparing the difference between the "actual" and "predicted" postoperative refractive errors. Repeated measures analysis of variance (ANOVA) tests were done to have pair-wise comparisons between the formulas and P < 0.05 was considered significant. A subcategory of axial length 24.5-26.5 mm was also tested. Holladay 1, Hoffer Q and SRK/T formulas showed a slight tendency toward resultant hyperopia, with mean error of +0.24 diopters (D), +0.58 D, and +0.92 D, respectively. The Holladay 1 formula provided the best predictive result overall.