Evaluation of 9 IOL power calculation formulas using a heteroscedastic statistical method and a new method of IOL constant optimization.

PURPOSE: To evaluate the prediction accuracy of 9 IOL power calculation formulas using a heteroscedastic statistical analysis and a novel method for IOL constant optimization.

DESIGN: Retrospective case series.

METHODS: The LenStar LS900 (Haag-Streit, Koeniz, Switzerland) was used for the preoperative biometry. The predicted SE refraction of the implanted IOL were calculated for: Barrett Universal II, EVO-2.0, Hill RBF-3.0, Hill-RBF 2.0, Kane, PEARL-DGS, SRK-T, Hoffer-Q and Holladay-1. IOL constants were optimized prior to the analysis. A heteroscedastic statistical method was used to compare the standard deviation (SD) of prediction errors (PE).

RESULTS: Two hundred seventy-eight eyes of 278 patients were included. The SD of the Kane was 0.4214D and was the lowest in this database. The SD of the PE of the Kane and EVO 2.0 were significantly lower than the SRK-T, Holladay 1, and Hoffer-Q. The SD of the PE of the PEARL formula was significantly lower than the SRK-T and Hoffer-Q. The SD of the PE of the Hill-RBF 3.0 was not significantly different to the Hill-RBF 2.0, Kane, EVO 2.0, Barrett Universal II and PEARL. No significant difference was found between the SD of the PE of the new generation formulas analysed.

CONCLUSIONS: the lowest SD of the prediction error was provided by Kane, followed by EVO 2.0 and PERL-DGS formulas. However, no statistically significant differences were found between the SD of the PE of new generation formulas. Further studies are necessary to evaluate the accuracy of these formulas in extreme eyes.