Objective: To compare central corneal thickness (CCT) measured by standard ultrasound pachymeter with optical coherence tomography (OCT) and corneal topography.
Material and Method: A cross-sectional study of central corneal thickness measurement by ultrasound pachymeter, OCT and corneal topography in 30 eyes of 30 healthy volunteers was done by a single examiner at Thammasat University Hospital between October 2010 and January 2011. The results were compared using ANOVA for repeated measures and Pearson correlation.
Results: Mean central corneal thickness by ultrasound pachymeter, OCT and corneal topography were 552.1 + 33.6 μm, 554.5 + 33.0 μm and 552.8 + 39.0 μm respectively. There were no statistically significant differences in the measurement results among the three modalities (p = 0.718). There was a significant linear correlation between OCT and ultrasound pachymeter (Pearson correlation = 0.985, p < 0.001), corneal topography and ultrasound pachymeter (Pearson correlation = 0.965, p < 0.001) and corneal topography and OCT (Pearson correlation = 0.965, p < 0.001).
Conclusion: Mean central corneal thickness among ultrasonic pachymeter, OCT and corneal topography were comparable and had significant linear correlations. In clinical practice, these three modalities could be interchangeable.

Keywords: Central corneal thickness, Ultrasound pachymeter, Optical coherence tomography, Corneal topography