Reproducibility and repeatability of central corneal thickness measurement in healthy eyes using four different optical devices

Abstract

The aim of the study is to compare the measurements of central corneal thickness (CCT) performed by two examiners with four different methods at different times inter- and intra-individually. Thirty healthy people were included in the study. In these measurements, an optical low-coherence reflectometry (OLCR), an optic coherence tomography (OCT), a specular microscopy (SM), and a corneal topography (CT) were used. Two examiners performed the measurements in a consecutive manner. After 1-7 days of the first measurements, the second measurements were performed again consecutively. The mean of three measurements was taken in each session for all devices. In OCT measurements, there was a significant difference between two examiners in both sessions (p < 0.001), while no significant differences were found between two examiners in first and second sessions in SM, CT, and OLCR measurements. When each examiner's measurements were compared to two sessions, there were no significant differences (p > 0.05, for all) except the SM measurements of the first examiner (p = 0.041). When the first measurements of two examiners were compared, the smallest values were of OCT. At the first session of two examiners, there was a significant difference between OCT and CT measurements, and between OCT and OLCR (p < 0.001, p = 0.002 for the first examiner and p < 0.001 for the second examiner, respectively). Our study showed that CCT measurements made by CT and OLCR methods were almost same and highly correlated for both the examiners' measurements. CCTs measured by OCT were on average 30 mu m thinner than CT and OLCR.