Belin ABCD Progression Display Identifies Keratoconus Progression Earlier Than Conventional Metrics

PURPOSE: To compare the progression rate and time to progression determined using the Belin ABCD Progression Display (BAPD) with conventional metrics in patients with keratoconus (KC). DESIGN: Retrospective comparison of progression assessment. METHODS: Patients 18 years and older and 35 years and younger with at least 1 year of follow-up and 3 Pentacam (Oculus, Inc) visits were included in the study. Progression was evaluated by selecting either the first visit or the first 2 visits individually as the baseline on the BAPD, and the red gate was used to determine progression (variability in any A, B, and C parameters >= 95% CI or any 2 parameters >= 80% CI). An increase of >= 1 diopter in corneal astigmatism and curvature parameters and a >= 2% reduction in thickness parameters constituted progressive disease. RESULTS: Two hundred seventy-seven eyes of 155 patients were included. The 2 baseline visit criteria identified the highest progression (n = 186 [67.2%]), followed by the single baseline visit (n = 158 [57%]), minimum corneal thickness (n = 114 [41.2%]), central corneal thickness (n = 111 [40.1%]), maximum keratometry (n = 76 [27.4%]), corneal astigmatism (n = 55 [19.9%]), back mean keratometry (n = 50 [18.1%]), and front mean keratometry (n = 31 [11.2%]) criteria. The median time to progression was shortest using the single baseline visit criterion (11 months), followed by the 2 baseline visits (11.6 months), minimum corneal thickness (12.1 months), maximum keratometry (12.3 months), corneal astigmatism (14.8 months), central corneal thickness (16.6 months), back mean keratometry (18.4 months), and front mean keratometry (24.4 months) criteria. In a subgroup analysis, progression could be identified 4 to 7 months earlier with the BAPD in eyes that were also progressive for maximum keratometry and central corneal thickness. CONCLUSIONS: BAPD detects progression at a higher rate and earlier than conventional parameters. (C) 2021 Elsevier Inc. All rights reserved.