Prediction of Posterior-to-Anterior Corneal Curvature Radii Ratio in Myopic Patients after LASIK, SMILE, and PRK Using Multivariate Regression Analysis

The ratio of posterior-to-anterior curvature radii of the cornea (P/A ratio) is an important element in determining corneal refractive power. P/A ratio has been well studied in patients prior to undergoing refractive surgery, but its postoperative value remains less so. We aimed to examine the value of preoperative characteristics of refractive surgery patients in predicting the 1-year postoperative P/A ratio in LASIK, PRK, and SMILE using both linear and multivariate regression analyses. This was a retrospective study that included patients with manifest refraction spherical equivalents (MRSE) from -7.71D to -0.25D. In total, 164 eyes underwent LASIK, 183 underwent PRK, and 46 underwent SMILE. All patients had preoperative and 1-year postoperative front sagittal and back sagittal keratometry measurements at 4, 5, and 6 mm around the corneal vertex. Postoperative P/A after LASIK, PRK, and SMILE was found to be significantly correlated with MRSE and preoperative P/A. Stepwise variable selection in multivariate regression revealed that spherical equivalent was the most significant predictor of postoperative P/A. When coupled with other preoperative characteristics, including P/A, age, asphericity, and keratometry, the multivariate regressions were able to produce models with high predictive value in LASIK (adjusted R-2: 0.957), PRK (adjusted R-2: 0.934), and SMILE (adjusted R-2: 0.894).

Automated summary

This study aimed to investigate the predictive value of preoperative characteristics in refractive surgery patients for the 1-year postoperative posterior-to-anterior curvature radii of the cornea (P/A ratio) using linear and multivariate regression analyses. The results showed significant correlations between postoperative P/A and manifest refraction spherical equivalent (MRSE) and preoperative P/A. Multivariate regression analysis revealed that MRSE was the most significant predictor of postoperative P/A. When considering other preoperative characteristics such as P/A, age, asphericity, and keratometry, the multivariate regressions produced models with high predictive value in LASIK, PRK, and SMILE.