Abstract

SO.15.08

Dynamic contour tonometry and Goldmann applanation tonometry: a comparison study

Astakhov Y. S., Akopov E. L., Potyomkin V. V.
Department of Ophthalmology, St.Petersburg Pavlov State Medical University
Presenter: Dr. Vitaly V. Potyomkin

Objective: The Pascal dynamic contour tonometer (DCT, Swiss Microtechnology AG) was recently introduced as a new method of intraocular pressure (IOP) measurement that is independent of central corneal thickness (CCT) and its biomechanical properties. Purpose of the study was to compare IOP measurements with Goldmann applanation tonometer (GAT) and with DCT.
Methods: In a prospective study three consecutive IOP measurements with GAT and with DCT were made on 206 eyes (111 patients) with primary open angle glaucoma, 26 eyes (13 patients) with ocular hypertension and 136 eyes of 72 healthy subjects. Tonometry was followed by central corneal pachymetry and keratometry.
Results: Correlation between DCT and GAT was found to be high (r=0.81; P<0.001). DCT IOP was generally higher than GAT IOP (mean difference +0.44 mm Hg). The difference between DCT and GAT IOP correlated with CCT (r=-0.44; P<0.001). Both methods were not affected by corneal curvature, but GAT was remarkably affected by CCT. Second DCT IOP reading was 0.38 mm Hg lower than the first one, the third was 0.22 mm Hg lower than the second one, which was statistically significant. No significant difference between GAT consecutive measurements was found. It was impossible to obtain valid readings with DCT in three hypotonic eyes (GAT IOP lower than 10 mm Hg).
Conclusions: Both DCT and GAT are highly reproducible methods of IOP measurement. Unlike GAT DCT is not influenced by CCT. DCT has a slight tonometry effect resulting in lower consecutive measurements. DCT is also not applicable in hypotonic eyes.

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