Correlation of Topometric and Tomographic Indices with Visual Acuity in Patients with Keratoconus

Abstract

Purpose: To evaluate the correlations of Pentacam keratometric, topometric (derived from front surface curvature) and tomographic (derived from 3D corneal shape analysis) indices with best corrected visual acuity in patients with keratoconus. Materials and methods: One eye randomly selected of 123 patients with bilateral keratoconus was retrospectively enrolled. All patients underwent a comprehensive ophthalmic examination including subjective refraction, distance best-spectacle corrected visual acuity (DCVA) measurement, and rotating Scheimpflug corneal tomography (Pentacam HR; Oculus, Wetzlar, Germany) at the same office visit. The correlations between the logarithm of the minimum angle of resolution (LogMAR) of DCVA and keratometric indices, topometric indices and tomographic indices were tested with nonparametric Spearman correlation coefficients (?). Results: The mean LogMAR DCVA was 0.32 (~20/42) ±0.27 [range: –0.10 (20/15) to 1.30 (20/400)]. There were strong correlations between DCVA and many keratometric, topometric and tomographic indices. A strong positive correlation was found between DCVA and BAD-Df (? = 0.648, p < 0.001), BAD-Db (? = 0.633, p < 0.001), K2 (? = 0.643, p < 0.001), Kmax (? = 0.608, p < 0.001), TKC (? = 0.558, p < 0.001), BAD-D (? = 0.577, p < 0.001), ISV (? = 0.573, p < 0.001), CKI (? = 0.530, p < 0.001), KI (? = 0.531, p < 0.001). A strong negative correlation was seen between DCVA and Asph Q front 30° (? = –0.521, p < 0.001). Conclusion: There are significant correlations between visual acuity and Pentacam parameters. Such parameters may be considered for improving staging of the disease, as well as for monitoring progression or treatment as outcome measures. There is a potential for combining parameters to enhance the correlations.