Abstract
Purpose :
There are always unexpected hyperopic outcomes with intraocular lens (IOL) power calculation formulas for high myopia and still unclear which formula is more suitable for high myopia. We performed a retrospective study to evaluate and compare the accuracy of different IOL power calculation formulas for eyes with an axial length (AL) greater than 26.00 mm.
Methods :
This retrospective study reviewed 407 eyes of 219 patients with AL longer than 26.0 mm. The refractive prediction errors (the difference between the actual postoperative refractive outcome and the predicted refraction) of IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, Barrett Universal II) using User Group for Laser Interference Biometry (ULIB) constants were evaluated and compared. Eyes were divided into groups by using plus-power, zero-diopter and minus-power IOLs.
The differences in the MNE, MAE, and median absolute error between formulas were assessed using the Wilcoxon signed-rank test. The Bonferroni correction was used for multiple comparisons. The association between refraction prediction error and AL were assessed using Spearman’s rank correlation. P-values less than 0.05 were considered statistically significant.
Results :
Two hundreds eighty-eight eyes of 183 patients were enrolled, the mean AL was 29.17 ± 2.46 mm; these included 265 eyes with plus-power IOL (Group A), 22 eyes with minus-power IOL (Group B), and 1 eye with zero-diopter IOL. In Group A, SRK/T, Haigis, Barrett Universal II formulas had similar Mean Absolute Error (MAE), but statistical difference was seen with Holladay and Hoffer Q formulas (p＜0.005) (Table 1). In Group B, there were no statistical differences between all formulas, but the inter-quartile range and MAE of the Barrett Universal II formula were the lowest among all the formulas (Table 1 and Table 2), and this formula yielded the highest percentage of eyes within ±0.5 D and ±1.0 D of the target refraction (Figure).
Conclusions :
For high myopic eyes with plus-power IOL, the SRK/T, Haigis, Barrett Universal II formulas had similar predictive outcome. For eyes with minus-power IOL, the Barrett Universal II formula may be a more suitable choice.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.