Central Corneal Thickness Measured By Ultrasound Pachymetry Or Pentacam As A Predictor Of Primary Open-Angle Glaucoma

Abstract

Purpose: : To determine the capacity of central corneal thickness (CCT) determined by ultrasound pachymetry (UCT) or using the Pentacam (pupil axis thickness, PAT and minimum corneal thickness, MCT) to discriminate between healthy controls and patients with primary open-angle glaucoma (POAG).

Methods: : UCT, PAT and MCT were determined in in the right eyes of 73 control subjects and 75 POAG patients. The normality of the distributions shown by the three variables was confirmed in the two data sets (control and POAG) using Kolmogorov-Smirnov and Saphiro-Wilk tests. Differences between the two data sets for each variable were identified using a t-test for independent samples. Three univariate binary logistic regression models (to discriminate between POAG and normality) were constructed in which the predictive variables were respectively UCT, PAT or MCT.

Results: : All three variables showed a normal distribution in the two samples. Controls and patients failed to differ significantly in terms of UCT (p=0.17) but did differ in terms of PAT (mean difference 19.88 microns in favour of controls; 95% CI: 5.61-34.15) and MCT (mean difference 17.65 microns in favour of controls; 95% CI: 3.05-32.25). The logistic regression model for UCT was not significant (p=0.17) but significant discriminatory capacity was shown by PAT (expB=0.98; 95% CI: 0.97-0.99; sensitivity: 58.7%; specificity: 63.1%) and MCT (expB=0.99; 95% CI: 0.98-0.998; sensitivity: 61.9%; specificity: 63.1%).

Conclusions: : CCT measures determined using the Pentacam (PAT and MCT) showed a similar yet not inappreciable capacity to discern between the control and glaucoma patients considering this is not an ad hoc diagnostic test for glaucoma. In contrast, CCT determined by pachymetry (UCT) lacked this capacity.

Keywords: clinical (human) or epidemiologic studies: risk factor assessment