Repeatability of Pentacam peripheral corneal thickness measurements.

Abstract Purpose To assess the repeatability of corneal thickness (CT) measurements, along the horizontal meridian up to 5 mm from centre, in healthy eyes with the Pentacam instrument. Methods CT was measured in 82 right eyes (82 healthy subjects) at 11 corneal locations nominally 1 mm apart along the horizontal meridian with Scheimpflug topography Pentacam. Two consecutive scans were performed in quick succession. The repeatability of CT was determined by assessing differences between measurements and calculating the coefficient of variation (CV). The relative repeatability (difference) was calculated as the ratio of the absolute peripheral CT difference to the central thickness. A variant of Bland–Altman analysis was carried out to determine the effect of the overall magnitude of CT on the absolute and relative differences. Results Mean CT (μm) at the temporal 5 mm location was 770 ± 51 and 823 ± 56 μm at the corresponding nasal location; central CT was 554 ± 36 μm. Good repeatability (CV  p  = 0.308 ANOVA Games–Howell). Conclusions Pentacam shows good repeatability for pachymetry measurements up to 5 mm away from the corneal apex across the horizontal meridian, even though repeatability decreases slightly towards the periphery. A single Pentacam scan will be sufficient for most clinical applications.