A Novel Metric To Monitor Early Progression in Keratoconus: Epithelial Backscatter

Abstract

PurposeTo assess the keratoconus progression over the course of one-year using epithelial and anterior stromal backscatter, Belin ABCD progression display, and various Pentacam (R) parameters and to determine whether backscatter measurements can be utilized to monitor progression.MethodsThis single-centre, retrospective, longitudinal, observational study evaluated change in epithelial and anterior stromal backscatter (using the line densitometry feature of the Pentacam (R)) and the flat, steep, mean and maximum keratometry, Belin ABCD progression display, corneal elevations, Belin/Ambr & oacute;sio enhanced ectasia display (BAD-D), pachymetric progression index (PPI), maximum Ambr & oacute;sio relational thickness (ARTmax), and topometric indices, between baseline and one-year in 37 eyes (37 patients) with keratoconus.ResultsWhen compared to the baseline after one-year, epithelial backscatter increased (p < 0.05); posterior radius of curvature, BAD-D, average PPI, index of vertical asymmetry (IVA), and index of height decentration (IHD) worsened (p < 0.05); and the anterior stromal backscatter, keratometry values, Belin ABCD stages, thinnest pachymetry, elevations, and ARTmax remained stable (p > 0.05). There were statistically significant weak-to-moderate correlations between the backscatter values and Pentacam (R) parameters (p < 0.05).ConclusionEpithelial backscatter can be considered a novel parameter to monitor the progression of keratoconus, as it was found to have similar abilities to those of the posterior radius of curvature, BAD-D, average PPI, IVA, and IHD, all of which demonstrated early evolution during one-year of follow-up, while the front keratometric data exhibited no progression. Moreover, by generalizing single-point backscatter data to the entire corneal surface, epithelial backscatter can be integrated into Pentacam (R) maps as a novel feature in keratoconus diagnosis and progression follow-up.