Comparison of pascal dynamic contor tonometry and goldmann aplanation tonometry and effect of central corneal thicness on intraocular pressure measurements

Purpose: To compare the Pascal dynamic contor tonometry (DCT) and Goldmann aplanation tonometry (GAT) in cases with primary open angle glaucoma (POAG), ocular hypertension (OHT) and control group and to evalute the effect of central corneal thickness (CCT) and other corneal parameters on the measurements of intraocular pressure (IOP).Patients and Methods: The IOP of fifty cases with POAG, 43 cases with OHT and 50 cases of control group were measured with GAT and DCT. The CCT of the cases were measured by ultrasound pachimetry. The corneal curvature and astigmatism levels of the cases were determined. GAT and DCT were compared in right and left eyes of the cases. The effect of CCT and other corneal parameters on GAT and DCT was detected.Results: GAT and DCT measurements were correlated in all groups. The meuserements with DCT were significantly higher than GAT measurements in POAG and control group. There was no significant difference between GAT and DCT in OHT group. The difference between DCT and GAT was higher in cases with low IOP levels whereas the difference was smaller in high IOP levels. The CCT in the group with OHT was significantly higher than in controls and cases with POAG. GAT and DCT were correlated with CCT but the correlation between GAT and CCT was higher than the correlation between DCT and CCT. Difference in IOP measurements between DCT and GAT was higher in cases with lower CCT. GAT and DCT measurements were not effected by age, corneal curvature and astigmatism.Conclusion: This study suggest that, DCT seems to be reliable method for intraocular pressure mesurement, which is influnced by CCT lower than GAT. New threshold levels in glaucoma diagnosis should be determined for DCT.Key words: Pascal dynamic contour tonometry, Goldmann aplanation tonometry, primary open angle glaucoma, ocular hypertension, central corneal thickness