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.