Comparative measurement of central corneal thickness using Pentacam, ocular response analyzer, and ultrasound pachymetry devices for normal, glaucomatous, and keratoconic eyes

Abstract

Purpose The aim of the study was to compare central corneal thickness (CCT) measurements using Scheimpflug imaging (Pentacam), ocular response analyzer (ORA), and ultrasound pachymetry (USP) devices for normal, glaucomatous, and keratoconic eyes. Patients and methods This was a prospective study that enrolled 170 eyes of 85 patients: 86 normal eyes, 50 eyes diagnosed as primary open angle glaucoma (POAG), and 34 eyes with keratoconus (KC). The CCT was measured using three machines - USP, Pentacam, and ORA - at the same time by two expert operators. Microsoft Excel, the Student t -test, and analysis of variance test were used for statistical analyses. Results The mean age of the three groups, normal, POAG and KC patients were 45 ± 17.7, 48 ± 7.8 and 26 ± 15.6 years respectively. CCT measurements using USP, Pentacam, ORA revealed: 552 ± 26.2 μ, 562 ± 23.3 μ and 569 ± 29.7 μ for normal eyes, 559 ± 13.4 μ, 570 ± 22.6 μ, and 587 ± 27.6 μ for POAG eyes, and 482 ± 17.7 μ, 505 ± 7.8 μ and 516 ± 8.5 μ for KC eyes respectively. It was noticed that, readings using USP shows reduced values in comparison to two other machines. USP and Pentacam were relatively comparable machines. Conclusion The measurements of CCT using ultrasound and Pentacam instruments had significant linear correlations with one another. Both methods had highly satisfactory measurement repeatability. Reading using ORA gives higher values.