Effects of corneal, refractive and biometric parameters on intraocular pressure mesaurements with dynamic contour tonometer, noncontact tonometer, tonopen and goldmann applanation tonometer

To compare intraocular pressure (IOP) measurements of Pascal dynamic contour tonometry (PDCT) with those of tonopen, Goldmann applanation tonometry (GAT) and noncontact tonometer (NCT) in ocular hypertensive (OHT) and normal individuals and to assess how corneal, refractive and biometric parameters effects these measurements. Materials and Methods: Four hundred-eighty eyes of 240 patients were included in the study. Those 120 patients with IOP values above 21 mmHg consitituted the OHT group while 120 normal indiviuals without IOP elevation constituted the control group. All eyes underwent refraction examination, keratometric measurement, axial lenghth measurement and central corneal thickness (CCT) measurements. Then, IOP was measured with DCT, GAT, NCT and tonopen, with 5 minutes intervals and in random order. Difference between these tonometers? measurements and correlations between IOP and refraction, CTT, keratometry and axial length were statistically analyzed. Findings: The mean CCT was 578.07 ± 30.38 ?m, and 546.05 ± 33.66 ?m, in OHT and control groups, respectively. There were no correlations between tonometers? measurements and keratometry, sphreical equivalent and axial length. In the control group, while CCT showed moderate correlations with GAT and NCT, there was a weak correlation with tonopen; no correlation between CCT and DCT measurements were detected. In the OHT group there was a weak correlation with CCT and tonopen measurements, and moderate correlations with CCT and other tonomoters? measurements. In corneas thinner than 520 ?m, there was no correlation with CCT and DCT measurements. In corneas between 520 and 580 ?m, there was a weak correlation between CCT and IOP mesaurements with GAT and NCT, while there was none with DCT and tonopen. Above 580 ?m, while there was a very weak correlation between CCT and mesaurements with GAT and tonopen, DCT was influenced the most.