Influence of age, central corneal thickness, and quality score on dynamic contour tonometry

Abstract

Aims: To compare the IOP measurements obtained with dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT), and to analyse the influence of central corneal thickness (CCT) and age on both measurements, and the influence of the quality score on DCT readings.MethodsA total of 500 healthy subjects with no prior history of glaucoma or ocular hypertension (age: 7-86 years) were consecutively recruited. GAT, DCT, and CCT measurements were obtained from both eyes of each individual, in this order, by three observers. The mean of five CCT measurements was used for analysis. DCT measurements were accepted when quality scores varied between 1 (higher quality) and 3 (lower quality).ResultsMean DCT measurements were 3.2 mmHg higher than GAT readings. CCT values varied between 449 and 653 m. IOP measured by GAT correlated strongly with CCT (r 2 0.28, P0.001), whereas DCT readings correlated poorly with CCT (r 2 0.01, P0.017). Both DCT (r 2 0.01, P0.044) and GAT (r 2 0.01, P0.001) measurements correlated poorly with age. Bland-Altmann analysis revealed disagreement between DCT and GAT readings, with 95% confidence intervals of 6.7 mmHg. Quality scores for DCT measurements were 1 (n369, 36.9%), 2 (n340, 34.0%), and 3 (n291, 29.1%). DCT readings with quality score of 3 (18.83.4 mmHg) were significantly higher than those with quality scores of 1 (16.72.9 mmHg) and 2 (17.42.9 mmHg; P0.001).ConclusionsDCT is not influenced by CCT, unlike GAT. Both DCT and GAT measurements are not influenced by age. DCT measurements with lower quality scores are associated with higher readings. © 2009 Macmillan Publishers Limited All rights reserved.