Test-retest variability of intraocular pressure and ocular pulse amplitude for dynamic contour tonometry: a multicentre study.

AIMS: To assess the test-retest variability of intraocular pressure (IOP) and ocular pulse amplitude (OPA) measurements utilising dynamic contour tonometry (DCT) and to evaluate possible influential factors. METHODS: The study included 350 consecutive subjects (175 glaucoma, 175 control; one eye per subject) from seven European centres. IOP was measured once with a Goldmann applanation tonometer (GAT) and twice by DCT (DCT1, DCT2) in a randomised sequence. OPA was also recorded for both DCT measurements. Differences (DCT1-DCT2; OPA1-OPA2; GAT-DCT1; GAT-DCT2) were assessed using the t test. The intraclass coefficient of correlation (ICC) and coefficient of variation (CoV) for DCT and OPA were calculated. RESULTS: DCT1 was 0.6+/-1.6 mm Hg higher than DCT2 (p0.90 and >0.76, and CoV=4.8-5.0% and 10.3-10.5%, respectively. DCT1 and 2 were 2.4+/-2.6 and 1.8+/-2.6 mm Hg higher respectively than GAT (p