Refractive outcomes after cataract surgery in eyes with pterygium: validation of a regression-based keratometric prediction model

Background This study aimed to validate a regression-based keratometric prediction model in eyes with pterygium using actual postoperative refractive outcomes after cataract surgery. Methods A retrospective paired analysis was performed in 20 unilateral eyes that underwent staged cataract surgery following pterygium excision. Predicted K values were calculated using a previously reported regression model based on CASIA2 anterior segment parameters. Intraocular lens (IOL) power was calculated using the Barrett Universal II formula. Mean K, spherical equivalent, refractive error, and absolute refractive error were compared among four keratometric methods (postoperative K, predicted K, preoperative K, and fellow-eye K) using the Friedman test followed by Bonferroni-adjusted Wilcoxon signed-rank tests. Sensitivity analyses were conducted after exclusion of toric IOL cases. Exploratory receiver operating characteristic analyses were performed to assess the influence of preoperative corneal parameters. Results Overall differences among the four methods were significant for mean K (p < 0.0001), spherical equivalent (p = 0.0003), refractive error (p = 0.001), and absolute refractive error (p = 0.014). However, no statistically significant differences were observed between postoperative K and predicted K in any parameter. Sensitivity analyses yielded consistent findings. Exploratory analyses suggested that preoperative corneal characteristics may influence refractive predictability. Conclusion In this paired analysis of 20 unilateral eyes, regression-based K estimation demonstrated refractive performance comparable to postoperative keratometry. These findings support the potential clinical utility of prediction-based keratometry as a practical alternative when postoperative K values are unavailable, although confirmation in larger prospective studies is required.