Accuracy of seven intraocular lens power calculation formulas: according to corneal power

Abstract

OBJECTIVES: To investigate the influence of corneal power on the accuracy of seven intraocular lens power calculation formulas in cataract surgery. METHODS: Retrospective case series study. A total of 336 eyes were enrolled from 336 patients undergoing uncomplicated cataract surgery. The Barrett Universal II, Emmetropia Verifying Optical V.2.0 (EVO2.0), Haigis, Kane, K6, Pearl­DGS, and SRK/T formulas were analyzed. The mean prediction error, absolute prediction error, mean absolute prediction error, median absolute error (MedAE), and the percentage of eyes with a prediction error (PE) within ±0.25 D, ±0.50 D, ±0.75 D, ±1.00 D and ±2.00 D were calculated. RESULTS: Across the entire cohort, the K6 formula had the lowest MedAE (0.23 D) and the highest percentage of eyes within ±0.50 D (80.06%). In the flat corneal power group (mean of the keratometry reading ≤ 43.0 D), the EVO2.0 (optional) and Kane (all) formulas had the highest percentage of eyes with a PE within ±0.50 D (86.15%). In the steep corneal power group (mean of the keratometry reading ≥ 46.0 D), the K6, EVO2.0 (all), and EVO2.0 (optional) formulas had the highest percentage of eyes with a PE within ±0.50 D (all were 83.33%). CONCLUSIONS:Overall, the new-generation formulas performed better in eyes with extreme corneal power, particularly the EVO2.0 (optional) formula with flat corneal power and the K6 formula with steep corneal power. Both the old and new formulas displayed similar accuracy in eyes with medium corneal power.