Comparison of Central Corneal Thickness Measurements Obtained by RTVue OCT, Lenstar, Sirius Topography, and Ultrasound Pachymetry in Healthy Subjects

Purpose: To compare central corneal thickness (CCT) measurement results obtained by RTVue OCT, Lenstar, Sirius topography, and ultrasound pachymetry (UP) (OcuScan RxP Ophthalmic Ultrasound System, Alcon Laboratories) in healthy subjects. Materials and Methods: 256 eyes of 128 healthy subjects were included in the study. CCT measurements were obtained from the eyes for each subject using the UP, Lenstar, Sirius topography, and RTVue OCT instruments. Ultrasound pachymetry measurements were performed after the eyes were anesthetized with one drop of 0.5% proparacaine hydrochloride and were performed at the same day after 15 minutes after previous measurements. Results: Of 128 participants, 84 were male and 44 were female with a mean age of 33.15 +/- 12.95 years (ranging from 18 to 75 years). The mean CCTs for UP, Lenstar, Sirius topography, and RTVue OCT were 535.60 +/- 35.15 (440,00-668,00); 532.63 +/- 34.44 (449,00-650,00); 526.05 +/- 36.45 (314,00-640,00); 525.89 +/- 33.21 (437,00-646,00) mu m, respectively. The mean CCT measurements were statistically different among the three groups (p = 0.002). CCT measurements obtained using RTVue-OCT were significantly thinner than those obtained using UP (p = 0.009). Sirius CCT measurements were also thinner than UP (p = 0.011). Mean CCT measurements between UP and Lenstar were similar (p = 0.769). Measurements with Lenstar (r = 0.849), Sirius topography (r = 0.883), and RTVue OCT (0.949) were highly correlated with UP measurements. Conclusion: RTVue OCT and Sirius topography significantly underestimated the CCT compared with UP. Although highly correlated, the measurement values with these devices are not directly interchangeable in clinical practice.