Abstract
Purpose :
Predicting refractive outcomes of cataract surgery is more difficult in eyes that have undergone keratorefractive adjustments. Various free online intraocular lens (IOL) calculators have been created to account for prior surgical history in predicting IOL power and postoperative refraction. We performed a retrospective chart review on eyes with a history of LASIK or PRK that subsequently underwent cataract surgery to assess the accuracy of these formulas.
Methods :
We included 106 patients with 146 total eyes who underwent cataract surgery at a single refractive surgery center. Eyes were excluded if they had conditions that would influence refraction. Ocular measurements were inputted into the ASCRS, PEARL-DGS, and EVO calculators. The ASCRS calculator contained several formulae producing exact IOL powers to reach the actual post-operative refraction. EVO and PEARL-DGS produced predicted post-operative refractions for the implanted IOL power. IOL predictive error (IPE) and refractive predictive error (RPE) were calculated, and IPE was converted to RPE as needed. The RPE results were compared using a clustered Bland-Altman analysis, mean arithmetic error, mean absolute error, and median absolute error before and after lens optimization.
Results :
Through 146 eyes, the following formulas produced a myopic RPE: EVO (-0.01 ± 0.58 D), Shammas (-0.38 ± 0.61 D), Haigis-L (-0.11 ± 0.63 D), Galilei (-0.15 ± 0.76 D), Barrett True-K No History (-0.11 ± 0.59 D), Masket Formula (-0.01 ± 0.65 D), Modified-Masket (-0.24 ± 0.73 D), and Adjusted ACCP/ACP/APP (-0.39 ± 0.85 D). The following formulas produced a hyperopic RPE: Potvin-Hill Pentacam (0.16 ± 0.62 D), OCT (0.38 ± 0.63 D), Barrett True-K (0.06 ± 0.61 D), and PEARL-DGS (0.32 ± 0.63 D). The mean absolute errors after lens optimization were EVO (0.46 ± 0.35 D), Barrett True-K No History (0.46 ± 0.37 D), Barrett True-K (0.46 ± 0.4 D), Shammas (0.47 ± 0.38 D), OCT (0.49 ± 0.42 D), Potvin-Hill Pentacam (0.50 ± 0.37 D), PEARL-DGS (0.50 ± 0.38 D), Haigis-L (0.50 ± 0.39 D), Masket Formula (0.50 ± 0.41 D), Modified-Masket (0.56 ± 0.45 D), Galilei (0.6 ± 0.47 D), and Adjusted ACCP/ACP/APP (0.63 ± 0.57 D).
Conclusions :
The differences in mean outcomes between each formula are modest, ranging from zero diopters to almost half of a diopter. Increasing the number of eyes and additional analysis will determine whether the differences are statistically significant.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.