Accuracy of intraocular lens calculations in eyes with keratoconus

Intraocular lens calculations in keratoconus

Abstract

Purpose: 

To compare the prediction accuracy of the Barrett True-K for keratoconus with standard formulas (SRK/T, Barrett Universal II and Kane) and the Kane keratoconus formula.

Setting: 

Shaare Zedek Medical Center, Jerusalem, Israel and University Eye Clinic, Maastricht, the Netherlands.

Design: 

Multicenter retrospective case-series

Methods: 

Eyes with stable keratoconus undergoing cataract surgery were included. The predicted refractions were calculated for: SRK/T, Barrett Universal II, Barrett True-K for keratoconus (predicted and measured), Kane, and Kane adjusted for keratoconus formulas. Primary outcomes were prediction error (PE), absolute error (AE), and percentage of eyes with PE ±0.25D, ±0.50D, and ±1.00D. Subgroup analyses were performed based on the severity of the keratoconus.

Results: 

Fifty-seven eyes were included in the study. The PE was not significantly different from zero for SRK/T, Barrett True-K (predicted and measured), and Kane keratoconus formulas (range 0.09 to 0.22 D, p>0.05). The AE of Barrett True-K predicted (Median 0.14D) and Barrett True-K measured (Median 0.10D) were significantly lower from Barrett Universal II (Median 0.47D) and Kane (Median 0.50 D), p<0.001.

Conclusion: 

The Barrett True-K formulas for keratoconus had higher prediction accuracy as compared to new generation formulas and a similar prediction accuracy as compared to the Kane keratoconus formula.