Correlation between optic disc topography and retinal nerve fibre layer measurements in glaucoma

Abstract

To test the correlation between optic disc topography (as measured by confocal scanning laser ophthalmoscopy [CSLO]) and retinal nerve fibre layer (RNFL) measurements (as measured by scanning laser polarimetry [SLP]) in glaucoma. A total of 112 patients with primary open-angle glaucoma and 88 normal individuals were enrolled in the study. All individuals underwent a thorough ophthalmic evaluation, a 24-2 full threshold Humphrey visual field, SLP with the GDx (Version 1.0.12) and CSLO with the TOPSS. Receiver operator characteristic curves were created for each individual CSLO and SLP parameter. Linear correlations between the four best parameters from each device were calculated. Finally, linear correlations between the same variables, controlled for the severity of visual field damage, were calculated. The best individual parameters in the diagnosis of glaucoma for each device were cup area, vertical cup : disc ratio, cup : disc area ratio and average cup depth for CSLO, and the Number, maximum modulation, ellipse modulation and superior nasal for SLP. Moderate to strong correlations were observed in 62% of the pairs. However, only 6% and 12% of the correlations remained moderate when we controlled for the visual field mean deviation and correct pattern standard deviation, respectively. The correlation between optic disc topography and RNFL measurements in glaucoma patients is moderate and highly dependent on the level of visual field loss.