In humans, ssPERG parameters decreased with age at a rate that paralleled RGC losses and correlated with ganglion cell complex thickness and ganglion cell and inner plexiform layer thickness (GCIPLT). Histological studies in primates with experimentally induced glaucoma provided evidence that PERG losses were related to optic nerve damage. PERG has excellent repeatability and reproducibility, and recently, a user-friendly type of PERG, steady-state PERG (ssPERG), was developed, allowing for widespread utilization in clinical practice. PERG was shown capable of identifying RGC dysfunction years before average retinal nerve fiber layer (ARNFLT) losses were detected by OCT, and before vision loss was detectable with standard automated perimetry (SAP). PERG has diagnostic potential in glaucoma, and cross-sectional data consistently revealed PERG losses in GS. Pattern electroretinogram (PERG) is an electrophysiological test that utilizes a reversing checkerboard patterned stimulus to measure RGC function. Electrophysiological studies assessing RGC function therefore hold potential for identifying individuals with glaucoma suspects (GS) at the highest risk of developing visual impairment. Recent investigations provided evidence that a percentage of dysfunctional, but viable RGCs were present in early disease. RGC losses are evident in early disease before the onset of visual symptoms, and the percentage of lost RGCs before vision loss occurs is highly variable. Glaucoma is a group of optic neuropathies characterized by retinal ganglion cell (RGC) dysfunction and death, which results in vision loss. The associations among ssPERG parameters and structural measures were mediated by estimated RGC count. Steady-state PERG parameters demonstrated linear correlations with estimated RGC count. Six mediation analyses revealed that estimated RGC count mediated the relationships among ssPERG parameters, ARNFLT, and GCIPLT. Pearson correlations revealed that ssPERG magnitude and magnitudeD correlated with ARNFLT (r ≥ 0.53, p 0.38, p 0.46, p < 0.002). ResultsĮstimated RGC count, average retinal nerve fiber layer thickness (ARNFLT), and average ganglion cell layer and inner plexiform layer thickness (GCIPLT) were reduced in GS eyes ( p ≤ 0.001 for all parameters). RGC count was estimated using the combined structure–function index. Eyes were divided into two groups based upon clinical data: healthy subjects and GS. Subjects underwent complete eye examinations, optical coherence tomography, standard automated perimetry, and ssPERG testing. In this prospective cross-sectional study, 22 subjects (44 eyes) were recruited at the Manhattan Eye, Ear, and Throat Hospital. To estimate retinal ganglion cell (RGC) count in glaucoma suspects (GS) and ascertain its relationships with steady-state pattern electroretinography (ssPERG) parameters.
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