AIM: To compare the difference in measurements of central corneal thickness(CCT)using A-scan,corneal specular microscopy and Pentacam in keratoconus.

METHODS: Between July 2012 and October 2012, the CCT of 31 patients(55 eyes)were measured by A-scan, corneal specular microscopy and Pentacam. The results were analyzed by F-test and Pearson correlation.

RESULTS: The values of CCT measured by A-scan(55 eyes), corneal specular microscopy(45 eyes)and Pentacam(52 eyes)were 469.87±57.56, 479.00±42.39, and 487.02±44.64μm, respectively; F-test results showed there were no statistical significant differences between CCT measured by three different instruments(P>0.05). The correlation between the measurements was evaluated using Pearson correlation coefficients. The CCT values by these three instruments were positively related by linear correlation analysis, A-scan and Pentacam measurements(r₁=0.758, P<0.01), A-scan and Pentacam(r₂=0.949, P<0.01), corneal specular microscopy and Pentacam(r₃=0.685, P<0.01).

CONCLUSION: There is a high correlation between these three instruments. A-scan and Pentacam are more precise than corneal specular microscopy. Pentacam system can measure the CCT easily, accurately and without any invasion. It is more suitable for people with keratoconus to monitor the every point of cornea and for people to do more deep research.