OBJECTIVE: To evaluate the variation of measurements in central corneal thickness
(CCT) using Orbscan corneal topography and to determine the relation between
the CCT and the intraocular pressure (IOP) measured. METHOD: CCT and IOP were
obtained by a single operator in 50 eyes of 25 volunteers with clinically
healthy eye using Orbscan topography and Topcon pneumotonometer respectively.
CCT was evaluated consecutively three times in each volunteer, and the mean is
used as the standard value for the pair of data. To avoid the variance of IOP
value caused by the diurnal variation, all subjects were examined between the
9:30 AM and the 11:30 AM. MAIN OUTCOME MEASURES: Intraocular pressure and mean
central corneal thickness. RESULTS: There was no significant variation(mean
standard deviation 5.97) of CCT in each individual during different taking of
measurement by Orbscan corneal topography. Mean IOP was 17.77 mmHg(95%
confidence interval(CI), 17.30-18.24 mmHg). Mean CCT was 557.4 microm(95% CI,
548-566.8 microm). Pooling all pairs of data, there was no statistically significant correlation
between the central IOP and CCT in any subject (Pearson rank correlation
coefficient). CONCLUSION: In this group of subjects, no significant variation
in the CCT was found. Therefore, we suggest that a single measurement of CCT by
Orbscan corneal topography is sufficient for the pachometry evaluation. We
found no correlation between IOP and CCT measured by Topcon pneumotonometer and
Orbscan corneal topography in this study.