Corneal Epithelial Thickness Intrasubject Repeatability and its Relation With Visual Limitation in Keratoconus

To evaluate intra-subject repeatability of anterior segment optical coherence tomography (AS-OCT) combined with placido disc MS-39 (CSO, Firenze, Italy) and correlate epithelial thickness measurements and the degree of visual limitation in keratoconus patients. Reliability analysis and cross-sectional study. Setting: Vissum, Alicante, Spain. Subjects: Total of 167 eyes, of which 107 were from keratoconus patients and 60 were healthy. Procedures: Three repeated consecutive epithelial thickness measurements were taken: central 3.0 mm and the nasal, temporal, superior, and inferior regions at 3.0-6.0 mm and 6.0-8.0 mm. Main Outcome Measures: Intrasubject repeatability of epithelial indices was assessed and correlated to the degree of best-corrected visual acuity (BCVA). The intraclass correlation coefficient was ≥0.90, indicating highly repeatable measurements for both keratoconus and healthy eyes. In multivariate analysis, epithelial indices associated with worse BCVA were as follows: thinner 3 mm central (P = .04), thicker 8 mm superior (P < .001), and thinner 8 mm inferior (P