Epithelial Thickness Profile as a Method to Evaluate the Effectiveness of Collagen Cross-Linking Treatment After Corneal Ectasia

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Abstract
Purpose: To illustrate the hypothesis that epithelial thickness profile maps could be a useful adjunct to topography in monitoring patients after corneal collagen cross-linking (CXL) treatment. Methods: Epithelial thickness profile in vivo was measured by Artemis very high-frequency (VHF) digital ultrasound scanning (ArcScan Inc) across the central 10-mm corneal diameter of a patient before collagen CXL for corneal ectasia after LASIK and at intervals up to 2 years later. Manifest refraction, corneal topography, and corneal front-surface aberrations were also monitored. Epithelial thickness changes were cross-correlated with corneal topography changes and corneal front-surface aberration changes. Results: Corneal collagen CXL appeared effective in halting the progression of corneal ectasia. Manifest refraction showed a reduction in spherical equivalent over time after CXL in both eyes. Corneal topography demonstrated stable central keratometry in both eyes. Corneal wavefront aberrations demonstrated a reduction of higher order root-mean-square coma and spherical aberration in both eyes. The epithelial thickness profile was altered, with a slight reduction of the area of epithelial thinning and decreased peripheral thickening. This resulted in minimizing the difference between the thinnest and thickest epithelium and might indicate an improvement of the condition. There were no significant changes in minimum stromal and minimum corneal thicknesses. Conclusions: Epithelial thickness maps provide useful information for monitoring the progression of corneal ectasia after corneal collagen CXL, showing in this case, at least no further progression of the ectasia.