Repeatability of Central Corneal Thickness Measurement Using Rotating Scheimpflug Camera in Dry and Normal Eyes

Abstract

To compare the repeatability of central corneal thickness (CCT) measurement using the Pentacam between dry eyes and healthy eyes, as well as to investigate the effect of artificial tears on CCT measurement. The corneal thicknesses of 34 patients with dry eye and 28 healthy subjects were measured using the Pentacam. One eye from each subject was assigned randomly to a repeatability test, wherein a single operator performed three successive CCT measurements time points-before and 5 min after instillation of one artificial teardrop. The repeatability of measurements was assessed using the coefficient of repeatability and the intraclass correlation coefficient. The coefficient of repeatability values of the CCT measurements in dry and healthy eyes were 24.36 and 10.69 μm before instillation, and 16.85 and 9.72 μm after instillation, respectively. The intraclass correlation coefficient was higher in healthy eyes than that of in dry eyes (0.987 vs. 0.891), and it had improved significantly in dry eyes (0.948) after instillation of one artificial teardrop. The CCT measurement fluctuated in dry eyes (repeated-measures analysis of variance, P<0.001), whereas no significant changes were detected in healthy eyes, either before or after artificial tear instillation. Central corneal thickness measurement is less repeatable in dry eyes than in healthy eyes. Artificial tears improve the repeatability of CCT measurements obtained using the Pentacam in dry eyes.