Comparing the Degree of Agreement of Intraocular Pressures in Patients with Keratoconus using Goldmann Applanation Tonometer, Dynamic Contour Tonometry & Tonopen

AIM OF THE STUDY: The aim of this study was to measure and compare the intraocular pressure (IOP) in patients with keratoconus using Goldman Applanation Tonometer (GAT), Dynamic Contour Tonometer (DCT) and Tonopen and evaluate the possible influence of central corneal thickness (CCT) on the intraocular pressure measured with the three tonometers. METHODS: This was a prospective case control study of 41 keratoconus patients and 100 normal patients where the intraocular pressure was measured with the GAT, DCT and Tonopen. CCT was measured with an ultrasound pachymeter. RESULTS: The mean IOP as obtained with GAT, DCT and Tonopen was 12.06 ± 2.12, 14.83 ± 2.49, 12.34 ± 1.88 in keratoconus and 13.94 ± 1.96, 14.22 ± 2.04 and 13.36 ± 1.70 in normals respectively. The mean difference in IOP between tonometers was different for cases and controls and this was shown to be statistically significant (p<0.001) DCT tended to overestimate the IOP in both groups. In both keratoconus and controls a fair to good agreement was shown between GAT and DCT, an excellent agreement between Tonopen and GAT and a fair agreement between DCT and Tonopen (p