Accuracy Of Intraocular Lens Power Calculation Formulas In Flat Corneas: 12-Formulas Comparison
Published 2025 - 43rd Congress of the ESCRS
Reference: FP21.02 | Type: Free paper | DOI: 10.82333/bfwx-qs51
Authors: Steve Aaron Arshinoff* 1 , Runjie Bill Shi 2
1Ophthalmology and Vision Sciences,University of Toronto,Toronto,Canada, 2Faculty of Medicine and Department of Biomedical Engineering,University of Toronto,Toronto,Canada
Purpose
To assess the performance of intraocular lens (IOL) power formulas in eyes with flat corneas (mean keratometry – Km – reading ≤ 42D), aiming to guide more precise IOL selection
Setting
Ophthalmology department, ULS São José Lisbon
Methods
This was a retrospective case series including 52eyes of 52 patients, all with preoperative Km ≤ 42D. All patients underwentuneventful cataract surgery over the past 3 years with the implantation of a single-model monofocal in-th-bag IOL (Acrysoft AU0T00, Alcon). Using constants optimized for the entire database, refraction prediction errors werecalculated for the following formulas: Barrett Universal II (BUII), EVO 2.0, Hiagis, Hill-RBF v2.0, Hoffer Q, Holladay 1, Kane, Næser 2, PEARL-DGS, SRK/T, T2 and VRF-G. Mains outcomes included mean prediction error (PE) and its standard deviation (SD), mean and median absolute error (MAE and MedAE) and the percentage of eyes within ±0.25D, ±0.50D and ±1.0D0 were also calculated.
Results
The preoperative mean Km was 41.25 ± 0.86D. A significant myopic error was observed using the Haigis formula (-0.215, p=0.003) and a significant hyperopic error was observed with SRK/T (0.287, p<0.001). PE from the remaining formulas was not significantly different from emmetropia (p>0.05 for all). The formulas with the lower SD were PEARL-DGS (0.479), followed by VRF-G (0.480), Kane (0.481) and EVO 2.0 (0.483). Absolute errors were statistically different among the formulas (p=0.015), with Kane and PEARL-DGS performing significantly better than SRK/T (p=0.09 and p=0.01 for each comparison). Kane formula had the highest percentage of eyes within ±0.50D (86.5), being significantly higher than that of SRK/T (63.5%) – p=0.005.
Conclusions
This study highlights that newer-generation formulas (PEARL-DGS, VRF-G, Kane and EVO 2.0) lead to more accurate refractive results in eyes with flat corneas. These formulas reduce prediction error variations, making them more reliable even in cases with unusual biometry.