Purpose
Changes in corneal tomography have become increasingly important in clinical decision-making since the introduction of corneal collagen crosslinking as a treatment for keratoconus. This study aims to measure the inter- and intra-observer variability of Pentacam measurements in keratoconic eyes.
Methods
In 100 eyes of 100 patients with keratoconus, two examiners each acquired 2 Pentacam scans in a randomly selected order. Bland-Altman plots were constructed and 95% limits of agreement (LOA) were calculated for Kmax (steepest K) and corneal thickness at the thinnest location.
Results
The 95% limits of interobserver agreement for Kmax were -2.7D to + 2.9D. For patients with Kmax <54D (n=46) the 95% limits of interobserver agreement for Kmax were -0.8D to + 1.0D. For patients with Kmax >54D (n=54) the 95% limits of interobserver agreement for Kmax were -3.8D to + 4.0D. The 95% limits of interobserver agreement for pachymetry at the thinnest location were -19.1μm to +18.5μm.
Conclusions
Kmax measurements on Pentacam are less reproducible in advanced than in early keratoconus. These data shed new light on the precision of measurements made using Scheimpflug corneal tomography and will help clinicians to define and to identify tomographic evidence of progression of keratoconus.
Keywords: 479 cornea: clinical science •
550 imaging/image analysis: clinical •
574 keratoconus