Comparison of central corneal thickness measurements with a new optical device and a standard ultrasonic pachymeter.

PURPOSE

To compare central corneal thickness (CCT) values obtained with ultrasonic pachymetry and a new optical method using partial coherence interferometry (PCI).

SETTING

Department of Ophthalmology, Medical Health and Science Center, University of Debrecen, Debrecen, Hungary.

METHODS

The study comprised 136 eyes of 70 patients whose spherical refractive error was not greater than +/-6.0 diopters (D) and whose keratometric astigmatism was not greater than 2.0 D. Central corneal thickness was measured 5 times with a new optical device (ACMaster, Zeiss) and with an ultrasonic pachymeter (AL-2000, Tomey). All measurements were obtained by the same investigator.

RESULTS

Mean CCT was 531.2 microm +/- 3.9 (SD) with PCI and 547.8 +/- 36.0 microm with the ultrasonic device. The difference between groups was significant (P = .001). There was no difference between CCT values measured in right and left eyes (P = .55) with ultrasonography and PCI (P = .67). The coefficient variation was 0.73% for PCI and 6.5% for ultrasonography. Correlation between the CCT measurements with both devices was strong and statistically significant (Spearman correlation = .91, P = .001).

CONCLUSIONS

Mean CCT values measured by the PCI method were significantly smaller than those measured by the ultrasonic device. Central corneal thickness measured with PCI is more reproducible and seems to be more reliable than that measured by ultrasonography.