Abstract
Abstract: :
Purpose: To investigate the agreement in the measurement of intraocular pressure (IOP) obtained by PASCAL Contour Tonometry (PCT) and Goldmann Applanation Tonometry (GAT) in glaucoma patients and healthy subjects. Methods: 107 glaucoma patients and 73 healthy subjects were included prospectively. (Mean age 66 years ± 11 years, and 34 years ± 17 years, respectively). Glaucoma diagnosis was based on abnormal optic disk exam and repeatable abnormal visual field results using automated perimetry. In a randomized order, three consecutive IOP measurements were performed by one observer using both instruments on all subjects. Furthermore, ultrasonic pachymetry was performed on all eyes. Repeated Analysis of Variance was performed to determine within–observer (intraobserver variation) effects, and between– groups (glaucoma versus control) effects. Results: Mean IOP values in glaucoma patients were significantly higher compared to healthy subjects, measured with both devices (PCT: 20.5 ± 7.4 mm Hg vs. 14.7 ± 2.6 mm Hg, GAT: 20.2 ± 8.1 mmHg vs. 13.7 ± 3.3 mm Hg). No significant difference in mean IOP values between both instruments was found (P>0.05). Mean IOP values obtained by both instruments were significantly correlated in both groups (Glaucoma: Correlation coefficient r= 0.97, Control: Correlation coefficient r=0.82, P < 0.05). Central Corneal Thickness (CCT) did not differ statistically significant in both groups (Glaucoma group 544.7 ± 34.5 µm vs. Control group 543.7 ± 30.4 µm). Furthermore ANOVA revealed no significant effect of corneal thickness on the IOP measurement for both groups (glaucoma and healthy subjects) and both instruments. The DCT is able to measure additionally the ocular pulse amplitude (OPA). The OPA in glaucoma patients (2.85 ± 1.1 mm Hg) was significantly higher compared to healthy subjects (2.13 ± 0.66 mm Hg, P<0.05). Conclusions: PCT and GAT revealed a good correlation in IOP measurements of glaucoma and healthy eyes. Even in eyes with CCT < 520µm, and >550µm, IOP values using GAT and PCT did not differ statistically significant. The new PCT is a promising tool for measurement of intraocular pressure and ocular pulse amplitude.
Keywords: clinical research methodology