Corneal Changes in Progressive Keratoconus After Cross-linking Assessed by Scheimpflug Camera

Abstract

To evaluate corneal changes after corneal cross-linking (CXL) in progressive keratoconus with Scheimpflug imaging. This prospective analysis included 40 eyes from 22 patients with progressive keratoconus. Corneal CXL was performed in 25 eyes (CXL group) and 15 fellow eyes served as controls (control group). Uncorrected (UDVA) and corrected distance visual acuity (CDVA), thinnest corneal thickness (ThCT), posterior elevation, and Holladay equivalent keratometry values (K1, K2) were determined with Pentacam (Oculus Optikgeräte GmbH) before and 1 year after CXL. Area under the receiver operator characteristic (ROC) curve and multivariable general estimating equation models were used to determine the most sensitive parameters of corneal changes. Manifest sphere (-2.55±3.21 to -1.48±2.39 diopters [D], P=.02), UDVA (0.23±0.25 to 0.31±0.25, P<.001), and CDVA (0.58±0.28 to 0.72±0.19, P=.019) improved significantly in the CXL group. Significant decreases were found in ThCT (472.53±33.18 to 440.53±38.67 μm, P<.001), posterior elevation (68.33±28.69 to 22.67±16.21, P<.001), and keratometry values (K1 [45.06±4.55 to 43.51±4.67 D, P<.001], K2 [48.39±5.41 to 46.71±5.67 D, P<.001]) in the CXL group. These parameters remained stable in controls (P>.05). According to ROC analysis, posterior elevation change was the most characteristic parameter of corneal change after CXL (area under the curve=0.99). General estimating equation model showed that CXL (P=.001) and initial ThCT (P=.007) were significant predictors of decrease in posterior elevation with a significant negative interaction of initial ThCT on CXL effect (P=.005). Posterior elevation is a sensitive parameter to monitor corneal remodeling after CXL. Corneal CXL showed augmented effect on corneal protrusion in eyes with thinner corneas.