TJ-CEO
2009 , Vol 4 , Num 4
The Relationship Between Dynamic Contour Tonometer and Central Corneal Thickness
1Çanakkale Onsekiz Mart Üniversitesi, Göz Hastalıkları AD., Çanakkale, Yard. Doç. Dr.2Çanakkale Onsekiz Mart Üniversitesi, Göz Hastalıkları AD., Çanakkale, Asist. Dr. Purpose: To investigate the relationship between intraocular pressure (IOP) measured by Pascal Dynamic Contour Tonometry (DCT) and central corneal thickness (CCT).
Materials and Methods: A hundred-sixteen eyes of 58 glaucoma suspected or healthy subjects (23 male,35 female) with a mean age of 48.2±13.3 years were included in the study.After CCTs of all eyes measured by Ultrasonic pachymeter (NidekUS-4000,Japan), IOP was measured by DCT (Ziemer Group,Switzerland), then, by Goldmann Applanation Tonometer (GAT), (Optilasa,Spain). The relationship between measurements of these two tonometers and CCT was evaluated for statistical significance by Pearson correlation analysis.
Results: The mean value of CCT measurements was found to be 541.1±41.0(455-635) μm. Mean IOPs measured by DCT and GAT were; 19.6±3.3(12.6-29.4) mmHg and 18.5±3.1(12-28) mmHg, respectively. Although the mean difference between two devices was found to be, 1.1(-5.7 - +7.3) mmHg, it was seen that IOP differences obtained from both devices were decreasing while CCTs were increasing(r=-0.205, p=0.03), (Pearson correlation analysis).In 27 eyes in which CCT was thinner than 517 μm, the differences were always cut in favour of DCT device, while the values obtained from both devices could be higher in eyes with CCTs especially thicker than 540 μm.
Discussion: DCT seemed less effected from CCT especially in corneas thinner than 510 μm, resulting more correct measurements, however especially in eyes with corneas thicker than 540 μm, the results of measurements could be very similar to those results of GAT.We conclude that, in thin corneas on which it is not possible to form a nomogram according to CCT,1-2 mmHg addition could be done to the measurements obtained by GAT; however, we think that this should be confirmed by following studies with larger series. Keywords : Central corneal thickness, dynamic contour tonometer, goldmann, pascal, tonometer