Differentiation of Compressive from Glaucomatous Optic Neuropathy with Spectral-domain Optical Coherence Tomography

Purpose: To compare optic disc topography in eyes with compressive optic neuropathy (CON) and open-angle glaucoma (OAG) using spectral-domain (SD) optical coherence tomography (OCT) and Heidelberg retinal tomograph (HRT) (Heidelberg Engineering GmbH, Heidelberg, Germany).

Design: Cross-sectional, observational study.

Participants: A total of 200 eyes from 123 patients with CON (69 eyes) or OAG (58 eyes) and controls (73 eyes).

Methods: Univariate and multivariate analyses of HRT parameters, SD-OCT circumpapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters.

Main Outcome Measures: Circumpapillary RNFL, OCT ONH parameters, and HRT parameters.

Results: The univariate analysis of OCT parameters demonstrated significant differences between the temporal and nasal quadrants; clock hours 3 (55 vs. 73 μm), 4, 8 (93.9 vs. 70.7 μm), 9, and 10; vertical cup-to-disc ratio (C:D) (0.6 vs. 0.8) and cup volume (0.2 vs. 0.5) (P<0.001) between patients with CON and OAG, respectively. The CON discs were significantly different from normal discs for all OCT parameters except cup volume. The CON discs were not significantly different from normal discs for HRT parameters, except for mean RNFL thickness and cup shape measure. The OAG discs were significantly different from normal discs in all HRT and OCT parameters (P<0.001). Multivariate analysis demonstrated that the OCT 3 o'clock temporal sector, average C:D ratio, vertical C:D ratio, and cup volume measurements were able to differentiate OAG from CON.

Conclusions: Compressive optic neuropathy is associated with significantly thinner nasal and temporal sectors compared with OAG, whereas OAG results in larger cups and cup volume with OCT measurements. The Heidelberg retinal tomograph is not able to differentiate CON from normal discs.