Accuracy of intraocular lens power calculation formulae in children less than two years

Abstract

Purpose: To assess the accuracy of IOL power calculation formulae in children less than 2 years of age.

Design: Retrospective, comparative study, comprising of 128 eyes of 84 children.

Methods: We analyzed records of children less than 2 years with congenital cataract who underwent primary IOL implantation. Data were analyzed for prediction error using the 4 commonly used IOL power calculation formulae. We calculated the absolute prediction error with each of the formulae and the formula that gave least variability was determined. The formula that gave the best prediction error was determined.

Results: Mean age at surgery was 11.7 ± 6.2 months. Absolute prediction error was found to be 2.27 ± 1.69 diopters (D) with SRK II, 3.23 ± 2.24 D with SRK T, 3.62 ± 2.42 D with Holladay, and 4.61 ± 3.12 D with Hoffer Q. The number of eyes with absolute prediction error within 0.5 D was 27 (21.1%) with SRK II, 8 (6.3%) with SRK T, 12 (9.4%) with Holladay, and 5 (3.9%) with Hoffer Q. Comparison between different formulae showed that the absolute prediction error with SRK II formula was significantly better than with other formulae (P < .001). Prediction error with SRK II formula was not affected by any factor such as age (P = .31), keratometry (P = .32), and axial length (P = .27) of the patient. Axial length influenced the absolute prediction error with Holladay (P = .05) and Hoffer Q formulae (P = .002). Mean keratometry influenced prediction error (P = .03) with SRK T formula.

Conclusion: Although absolute prediction error tends to remain high with all present IOL power calculation formulae, SRK II was the most predictable formula in our series.