Comparison of dynamic contour tonometry with Goldmann applanation tonometry in glaucoma practice

To compare intraocular pressure (IOP) readings taken using dynamic contour tonometry (DCT) with IOP readings taken with Goldmann applanation tonometry (GAT) in eyes with glaucoma or ocular hypertension. The present study included 100 eyes in 100 patients with glaucoma or ocular hypertension. After pachymetry DCT and GAT were performed. Intraocular pressures as measured with DCT and GAT were compared with one another and with central corneal thickness (CCT). Mean DCT IOP measurements (20.1 +/- 4.3 mmHg) were significantly (p < 0.001) higher than GAT IOP values (17.9 +/- 4.7 mmHg). The mean difference between DCT and GAT measurements was 2.1 mmHg (range - 3.4 to 9.7 mmHg). The difference followed a normal distribution. Measurements made with DCT and GAT correlated significantly with one another (Spearman's rho = 0.761, p < 0.001). Neither GAT nor DCT measurements showed a significant correlation with CCT (537 +/- 39 mu m, range 458-656 mu m). Multivariate regression analysis has shown that the difference between DCT and GAT is influenced significantly by ocular pulse amplitude (r = - 0.334, p = 0.001) and it is not influenced by CCT (r = - 0.106, p = 0.292). In eyes with glaucoma or ocular hypertension, DCT facilitates suitable and reliable IOP measurements which are in good concordance with GAT readings. Variation in CCT cannot by itself explain the differences in measurements taken with DCT and GAT in a number of eyes.