Abstract
Retinal ganglion cells are distributed disproportionately with retinal eccentricity. Pattern electroretinogram (PERG) stimuli resulted in reduced responses with more eccentric stimuli. Therefore, we investigated whether PERG amplitude is associated with the location of visual field (VF) defect in primary open-angle glaucoma. Data from Twenty-nine glaucoma patients with a parafoveal scotoma (PFS) within the central 10° of fixation, 23 glaucoma patients with a peripheral nasal step (PNS), and 27 normal control subjects were analyzed in this study. Electroretinograms (ERGs) were obtained using a commercial ERG stimulator (Neuro-ERG). The thickness of the ganglion cell-inner plexiform layer (GCIPL) was measured using spectral-domain optical coherence tomography. A lower N95 amplitude was observed in both PFS and PNS compared to the normal control (Both P < 0.001). The N95 amplitude of the PFS group was significantly lower than that of the PNS group (P = 0.034). Average GCIPL thickness correlated positively with N95 amplitude (r = 0.368, P = 0.002), but did not correlate significantly with global mean sensitivity (r = 0.228, P = 0.073) or mean deviation on 24-2 standard automated perimetry (r = 0.173, P = 0.176). In conclusion, parafoveal VF defects were associated with the lower PERG amplitude. Therefore, it is necessary to take into account the location of VF defects in evaluating PERGs of glaucoma patients.
Highlights
The visual field (VF) test has been the foundation of glaucoma diagnosis and treatment[1]
We demonstrated that the pattern electroretinogram (PERG) amplitudes of glaucoma patients with parafoveal scotoma (PFS) or peripheral nasal step (PNS) were lower than those of normal control subjects
Our study has revealed that the N95 PERG amplitude was lower in the PFS group than in the PNS group
Summary
The visual field (VF) test has been the foundation of glaucoma diagnosis and treatment[1]. Several types of PERG were developed in which the visual angle was extended to 44° horizontally, which is similar to the horizontal visual angle (52°) examined by 24-2 standard automated perimetry (SAP 24-2)[5,10] It has not been extensively studied whether PERG parameters differ depending on the location of VF defects in glaucoma patients, even though conventional PERGs have been regarded as a central vision test stimulating the macula. The PERG response with stimulation of more eccentric regions decreased even at their respective optimal spatial frequencies[14] Given those findings, a PERG response may differ with subjects with parafoveal scotoma (PFS) compared to those with peripheral nasal step (PNS) quantitatively and qualitatively, even with the extended visual angle. We compared the PERG results between glaucoma patients with PNS and PFS
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