Electroretinography in glaucoma diagnosis

Abstract

Purpose of review Electrophysiological measures of vision function have for decades generated interest among glaucoma researchers and clinicians alike because of their potential to help elucidate pathophysiological processes and sequence of glaucomatous damage as well as to offer a potential complementary metric of function that might be more sensitive than standard automated perimetry. The purpose of this article is to review the recent literature in order to provide an update on the role of the electroretinogram (ERG) in glaucoma diagnosis. Recent findings The pattern reversal ERG (PERG) and the photopic negative response (PhNR) of the cone-driven full-field, focal or multifocal ERG provide objective measures of retinal ganglion cell function and are all sensitive to glaucomatous damage. Recent studies demonstrate that a reduced PERG amplitude is predictive of subsequent visual field conversion (from normal to glaucomatous) and an increased rate of progressive retinal nerve fiber layer thinning in suspect eyes, indicating a potential role for PERG in risk stratification. Converging evidence indicates that some portion of PERG and PhNR abnormality represents a reversible aspect of dysfunction in glaucoma. Summary PERG and PhNR responses obtained from the central macula are capable of detecting early-stage, reversible glaucomatous dysfunction.

Comparing three different modes of electroretinography in experimental glaucoma: diagnostic performance and correlation to structure

“…The three modes selected were mfERG, ff-ERG and PERG because they have each been evaluated extensively and proven effective in clinical studies of human glaucoma [19,21,13,14,22,23,20,24,15] as well as in previous laboratory studies in NHP eyes after retinal ganglion cell or optic nerve injury [34,28], including EG [35–39,17,40,41,29–31]. To our knowledge, however, no prior study has compared all three modes in the same cohort of glaucomatous eyes.…”

“…For these reasons, electrophysiological tests of vision function such as electroretinography (ERG) are thought to have a role in glaucoma management [13–15]. ERG testing also provides a non-invasive, objective measure of function that is easier to obtain in laboratory animals than those based on behavioral testing such as perimetry [16,17].…”

“…Several different ERG modes are known to be capable of monitoring RGC function in human glaucoma as well as in experimental glaucoma (EG) models [15,18]. For example, pattern ERG (PERG), full-field flash ERG (ff-ERG) and multifocal ERG (mfERG) techniques have all been studied extensively to determine their respective abilities to measure loss of RGC function [19–21,13,14,22–24,15,18].…”

“…For example, pattern ERG (PERG), full-field flash ERG (ff-ERG) and multifocal ERG (mfERG) techniques have all been studied extensively to determine their respective abilities to measure loss of RGC function [19–21,13,14,22–24,15,18]. Each technique has its advantages and drawbacks[24,15], the balance of which may depend on the setting (e.g., clinical versus research) or the subjects under study (e.g., human patients versus laboratory animals). However, to our knowledge, no single study has yet evaluated all three modes simultaneously to compare their diagnostic performance and correlation to measures of glaucomatous structural damage.…”

Comparison of photopic negative response measurements in the time and time–frequency domains

“…Evidence for a retinal ganglion cell source comes from animal studies showing that the PhNR is reduced or absent in macaques following intravitreal injection of tetrodotoxin as well as in experimentally-induced glaucoma [2,4]. The inner-retina source of the PhNR has made it a useful tool for assessing dysfunction in conditions including glaucoma [3,5–8], optic atrophy [1,9,10], idiopathic intracranial hypertension [11], and optic glioma [12]. …”