Diagnostic Capability of Pattern Electroretinogram and Three Circumpapillary Retinal Nerve Fiber Layer Thickness Circle Diameter Scans in Glaucoma Suspects

Purpose: To assess the diagnostic capability of pattern electroretinography (PERG) and varying circumpapillary optical coherence tomography (OCT) scan diameters in glaucoma suspects (GS). Methods: This is a prospective, cross-sectional study. Circumpapillary retinal nerve fiber layer thickness (RNFLT) was measured using spectral domain OCT in 49 eyes from 26 patients (36 normal, 13 GS) in three circle diameters (3.5, 4.1, and 4.7 mm). PERG measurements (Magnitude [Mag], MagnitudeD [MagD], MagnitudeD/Magnitude [MagD/Mag] ratio) were used. Based on clinical examination, participants were classified as controls or GS. Independent t-test and areas under the receiver operating characteristic curve (AUC) were obtained to determine the diagnostic capability of PERG and OCT. Results: Independent t-test revealed significant differences between controls and GS in age, sex, central corneal thickness (CCT), all PERG parameters, and global RNFLT (gRNFLT) in three circle diameters. All PERG parameters were correlated to all RNFLT sectors (r > 0.291; p < 0.041), except in the temporal and nasal sectors of the three circle scans. Spearman rho was highest in 3.5 and lowest in 4.7 mm circle scan. AUC demonstrated 3.5 mm gRNFLT had the highest diagnostic capability (AUC = 0.877), followed by 4.1 mm gRNFLT (AUC = 0.852), and 4.7 mm gRNFLT (AUC = 0.821). MagD showed the foremost diagnostic capability (AUC = 0.81), followed by Mag (AUC = 0.799) and MagD/Mag (AUC = 0.762). Conclusion: Global, superior, and inferior RNFLT in 3.5 and 4.1 mm diameters, and MagD performed best in discriminating GS from controls, suggesting that a larger scan of 4.1 mm may be equally useful in glaucoma diagnosis as the conventional 3.5 mm diameter. We recommend using PERG with OCT of 3.5 or 4.1 mm diameters for glaucoma suspect diagnosis.