Comparison of central corneal thickness measurements with three different optical devices

The purpose of this study was to compare and evaluate the agreement of central corneal thickness (CCT) values obtained with three different devices working according to optical principle in healthy eyes.

60 eyes of 60 individuals (30 men and 30 women) were enrolled in this study. CCT measurements performed with Scheimpflug-Placido topographer (Sirius), spectral-domain optical coherence tomography (RTVue) with an anterior segment module, and optical biometer (AL-Scan) were compared. Bland-Altman analysis was used to demonstrate agreement between methods.

The mean age was 30.07 ± 7.313 years (range, 18-47 years). The mean CCT values obtained by RTVue, Sirius, and AL-Scan were 518.25 ± 36.38 µm, 526.08 ± 36.33 µm, and 513.50 ± 39.09 µm, respectively. The mean differences in CCT were 7.83 ± 14.15 µm between Sirius and RTVue, 12.58 ± 11.87 µm between Sirius and AL-Scan, and 4.75 ± 4.50 µm between RTVue and AL-Scan. The mean CCT was statistically different among the three groups (p < 0.05). All three modalities of CCT measurements correlated closely with each other, with Pearson's correlation coefficients ranging from 0.924 to 0.961. The 95% limits of agreement were -19.90 to 35.56 µm between Sirius and RTVue, -10.69 to 35.85 µm between Sirius and AL-Scan, and -4.07 to 13.58 µm between RTVue and AL-Scan.

Different results could be obtained through different noncontact devices in CCT measurements. Although the measurement values obtained by these devices show a high level of correlation, it would be a more correct approach to not use them directly interchangeably in clinical practice. Evaluation and follow-up of CCT should be performed using the same device.