Electrophysiology in advanced glaucoma diagnostics and monitoring

Relevance Primary open-angle glaucoma (POAG) is characterized by chronic progressive damage to the retinal ganglion cell layer (RGC) and its axons, which leads to irreversible vision loss. The key method for diagnosing glaucoma is computer perimetry (CP) [1–3]. However, in patients with advanced glaucoma, there are certain difficulties in performing CP due to low visual acuity and psychoemotional state. In such cases, electrophysiological studies (EPS) provide objective data on the functional state of the GGC and optic nerve, which can be useful for diagnosing and monitoring glaucoma [3]. Electroretinography (ERG) is a method based on recording the bioelectrical activity of photosensitive retinal cells (including GGC) in response to light stimuli (flashes) or structured pattern stimuli (pattern ERG). The photopic negative response (PNR) is a negative potential that follows the b-wave in the photopic ERG. It is generated by retinal spiking neurons, including RGCs and amacrine cells. Visual evoked cortical potentials (VECPs) are a bioelectrical response of neurons in the cerebral cortex to afferent stimulation, allowing one to assess the functional integrity of the visual pathway from the retina to the visual cortex. In some cases, additional examination is required to more accurately determine the level of damage, including ERG to exclude retinal pathology [4, 5]. Conclusion Electrophysiological methods allow for an in-depth assessment of the functional state of the RGCs and optic nerve. A combination of methods allows one to obtain more information about the pathology of the retina and optic nerve. The objective nature of EFI makes it possible to diagnose and monitor glaucomatous optic neuropathy in patients with advanced stages of the disease, when standard subjective research methods are not informative enough. Key words: glaucoma; retinal ganglion cells; electroretinography; visual evoked cortical potentials; photopic negative response