Precision of intraocular lens power prediction in eyes shorter than 22 mm: An analysis of 6 formulas.

Purpose To analyze the precision of 6 intraocular lens (IOL) power calculation formulas in predicting refractive outcome in eyes with an axial length (AL) less than 22.0 mm. Setting Department of Ophthalmology, All India Institute of Medical Sciences, Raipur, India. Design Retrospective observational study. Methods Patients with an AL less than 22.0 mm were included in the study. If both eyes were eligible, a randomly selected eye was chosen. Optical biometry with partial coherence interferometry (PCI) was performed in all cases. Six formulas were analyzed: Barrett Universal II, Haigis, Hoffer Q, Holladay 2, RBF Method and SRK/T. The mean numerical error was defined as the difference between the actual postoperative spherical equivalent (SE) at the 1-month follow-up and the predicted postoperative SE. The median absolute error was calculated and compared between all 6 formulas after the zeroing of the mean numerical error by adjusting the lens constant individually for each formula. Results The study comprised 50 eyes of 50 patients. The Friedman test was applied to compare the median absolute error between the 6 formulas after the zeroing of the mean numerical error. Post hoc analysis and Bonferroni correction for multiple comparisons showed no significant statistical difference between them. Conclusion The Barrett Universal II, Haigis, Hoffer Q, Holladay 2, RBF method and SRK/T formulas were equally accurate in predicting the IOL power in eyes shorter than 22.0 mm. [ABSTRACT FROM AUTHOR]