2M.D., Pamukkale University Faculty of Medicine, Department Ophthalmology, Denizli/TURKEY
3M.D. Asistant Professor, Ankara University Faculty of Medicine, Department Bioistatistic, Ankara/TURKEY
4M.D. Professor, Pamukkale University Faculty of Medicine, Department Ophthalmology, Denizli/TURKEY Purpose: To compare the intraocular pressure (IOP) measured by dynamic contour tonometry (DCT), Goldmann applanation tonometry (GAT), non-contact tonometry (NCT) and Tono-Pen and also to assess whether ocular parameters such as corneal thickness, keratometry and axial length affect the measurements by the tonometers.
Materials and Methods: One hundred healthy subjects prospectively underwent IOP measurement with DCT, GAT, NCT and Tono-Pen. The correlation between the tonometer readings as well as the effect of keratometry, central corneal thickness (CCT), axial length and anterior chamber depth on IOP measurements were assessed.
Results: DCT readings were higher than NCT (ΔIOP=2.0±3.2 mmHg, p<0.001) and GAT (ΔIOP=1.3±2.1 mmHg, p=0.003) but not Tono-Pen (ΔIOP=0.1±2.7 mmHg, p=0.981). DCT, GAT and NCT correlated positively with CCT (p=0.039, p=0.020 and p=0.001). GAT and NCT readings were significantly higher in eyes with thick cornea (>568 μm) compared to eyes with thin cornea (<535 μm) (p=0.021 and p=0.003). Ocular parameters other than CCT did not have a significant effect on the readings of tonometers.
Conclusion: Despite significant correlation; DCT readings were higher than GAT and NCT but not Tono-Pen. DCT, NCT and GAT readings significantly correlated with CCT. GAT and NCT readings were significantly higher in eyes with thick cornea compared to eyes with thin cornea.
Keywords : Dynamic contour tonometry, Goldmann applanation tonometry, non-contact tonometry, pascal tonometry, Tono-Pen