Comparison of central corneal thickness measurements using three different imaging devices.

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

METHODS

A total of 120 eyes of 60 healthy individuals (36 men and 24 women) were enrolled in this retrospective study. CCT measurements were performed using an optical biometer (AL-Scan), spectral-domain optical coherence tomography (SD-OCT) (Topcon 3D) and ultrasonic pachymetry (UP) (Accupach VI), and the results were compared. Bland-Altman analysis was used to quantify the agreement between methods.

MAIN

RESULTS

The mean patient age was 28±5.73years (18-40years). The mean CCT values obtained by AL-Scan, UP, and SD-OCT were 532.4μm±29.7, 549μm±30.4, and 547μm±30.6, respectively. The mean differences in CCT were 15.30±9.52μm between AL-Scan and OCT (P<0.01), 17.15±8.42μm between AL-Scan and UP (P<0.01), and 1.85± 8.78μm between UP and OCT (P=0.067). All three methods of CCT measurement were closely correlated with each other.

CONCLUSION

The present study results suggest that, despite good agreement between the three devices, AL-Scan significantly underestimated CCT compared to UP and OCT. Therefore, clinicians should be aware that different results can be obtained using different devices for CCT measurements. It would be a better approach not to use them as interchangeable in clinical practice. CCT examination and follow-up should be performed using the same device, especially for patients who will undergo refractive surgery.