Evaluation of Steady State Pattern Electroretinography (ssPERG) in Discriminating Normal from Glaucoma Suspect and Glaucomatous Eyes

Abstract

Purpose: To evaluate the ability of ssPERG to discriminate between healthy, glaucoma suspect, and glaucomatous eyes.

Methods: We enrolled one eye of each of 15 healthy individuals; 15 glaucoma suspect eyes defined by having at least one of the following optic nerve changes (a cup to disc ratio > 0.6; inter-eye cup to disc ratio asymmetry > 0.2; retinal nerve fiber layer defects; neuroretinal rim notching; disc hemorrhage) plus abnormal nerve fiber layer by OCT and a normal SAP and 30 glaucomatous eyes with visual field (VF) loss) All subjects had VA better than 20/30. Normal subjects had normal VFs. Glaucoma was staged as early (mean deviation, MD>-6.0 dB) and moderate (mean deviation, MD>-6.0 dB) (15 eyes each). Synchronized single-channel ssPERGs were recorded using the Diopsys NOVA System (Diopsys, Inc. Pine Brook, NJ). An area under the curve (AUC) analysis was performed comparing the healthy eyes to the other groups.

Results: The AUCs for the healthy eyes compared to the three groups of patients were as follows: 1) glaucoma suspect eyes 0.70(0.50-0.89); early glaucomatous visual field damage 0.91(0.79-1.00); and moderate glaucomatous visual field damage 0.96(0.87-1.00). The sensitivity and specificity for discriminating mild glaucomatous eyes from health eyes was 0.87 and 0.93 respectively. The sensitivity and specificity for discriminating moderate glaucomatous eyes from healthy eyes was 0.93 and 1.00 respectively. The sensitivity and specificity for the glaucoma suspect eyes to healthy eyes was 0.54 and 0.80 respectively.

Conclusions: ssPERG is able to discriminate between healthy eyes, glaucoma suspect eyes and glaucomatous eyes and may be able to differentiate between eyes with early and moderate VF loss.

Keywords: 507 electrophysiology: clinical • 531 ganglion cells • 629 optic nerve