Reproducibility of keratometric measurements obtained with OCULUS® Pentacam® HR in the evaluation of keratoconus progression

Abstract

Purpose To determine the reproducibility of keratometric parameters obtained by OCULUS® Pentacam® HR in the evaluation of keratoconus progression. Methods Thirty nine eyes of 25 patients from the Cornea Department of the Centro Hospitalar de Lisboa Central were included in the study. Fourteen eyes presented with clinical and topographic diagnosis of keratoconus (stage 1‐3) and were defined as the “keratoconus without ring” group; 9 eyes had already an intrastromal ring implanted and were defined as the “keratoconus with ring”; the remaining 16 eyes, without clinical or topographic evidence of disease, were used as controls. Every eye was submitted to identical methodology: 5 consecutive keratometric measurements obtained with OCULUS® Pentacam® HR; central keratometry, SKmax, minimal pachymetry and anterior chamber depth were used to determine the existence of statistically significant reproducibility. Results Overall significant measurement variability was obtained in the “keratoconus without ring” group (Km 0.129 D vs 0.0375 D, SKmax 0.507 D vs 0.0625 D, Minpach 5.429 μm vs 2.5625 μm, ACD 0.024 mm vs 0.0194 mm), with highest variability in the subgroup of patients with more advanced disease. In the “keratoconus with ring” group statistically significant variability was found for all parameters except for anterior chamber depth (Km 0.289 D vs 0.0375 D, SKmax 0.444 D vs 0.0625 D, Minpach 4.333 μm vs 2.5625 μm, ACD 0.024 mm vs 0.0194 mm). Conclusion Keratometric measurements obtained with OCULUS® Pentacam® HR should be assessed cautiously in the evaluation of keratoconus progression, with or without intrastromal ring; the use of single measurements is unadvised.