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PurposeTo determine the ability of the photopic negative response (PhNR) of the uniform field electroretinogram (UF-ERG) to identify early glaucomatous changes in comparison to the checkerboard and bar stimuli of the pattern electroretinogram (PERG).MethodsForty-nine glaucoma patients were classified into two groups: glaucoma-suspect (23 eyes) and early to moderate glaucoma (30 eyes), based on their clinical examination and the results of standard automated perimetry. Thirty patients (30 eyes) with intraocular pressures (IOP) of 21 mmHg or less, with no history of reported high IOP, were included as controls. PERG and UF-ERG recordings were obtained on a Diagnosys D-341 Attaché-Envoy System. Visual field testing was done only for glaucoma-suspect and glaucoma patients.ResultsAll three tests (PERG bar stimulus, PERG checkerboard stimulus and PhNR) displayed significantly prolonged peak times for glaucoma and glaucoma-suspect patients, with delays ranging from 7.8 to 14.8%, depending on the test. The PERG bar stimulus also showed a significantly lower N95 amplitude for both glaucoma groups (with reductions of 26.0% and 33.0% for glaucoma–suspect and glaucoma groups, respectively). The PERG checkerboard N95 amplitude component had high sensitivity for detecting glaucoma patients but a low specificity (97% and 37%, respectively; AUC = 0.61). Overall, the PhNR peak time showed the highest sensitivity and specificity (77% and 90%, respectively; AUC = 0.87).ConclusionsPERG bar stimuli and the PhNR of the UF-ERG can be used in the clinical setting to detect glaucoma-related changes in glaucoma-suspect and glaucoma patients. However, our data confirm that the PhNR peak time has the best combined sensitivity and specificity.

Background/Objectives: The aim of this study was to evaluate the relationship between foveal avascular zone (FAZ) enlargement, retinal ganglion cell (RGC) dysfunction, and structural retinal measurements in glaucoma suspects (GS), using pattern electroretinogram (PERG) and optical coherence tomography angiography (OCTA) parameters. Methods: Thirty-one eyes (20 subjects) of GS status underwent comprehensive ophthalmologic evaluation including steady-state PERG, optical coherence tomography (OCT), and OCTA. FAZ area was measured using ImageJ software (version 1.54p), and PERG parameters (Magnitude, MagnitudeD, and MagnitudeD/Magnitude ratio) were analyzed. Partial correlation analyses were performed to assess associations between FAZ area, PERG parameters, and structural metrics including retinal nerve fiber layer (RNFL), ganglion cell layer–inner plexiform layer (GCL + IPL), and macular thickness. Results: After controlling for age, sex, central corneal thickness (CCT), intraocular pressure (IOP), and spherical equivalent, partial correlation analysis showed that FAZ area was significantly associated with both lower Magnitude (r < −0.503, p < 0.05) and MagnitudeD (r < −0.507, p < 0.05) values. PERG parameters were significantly correlated with superior and average RNFL thickness, as well as superior and superior temporal GCL + IPL thickness. FAZ area was significantly associated with multiple GCL + IPL and macular thickness sectors, but not with RNFL thickness. Conclusions: FAZ enlargement is significantly associated with RGC dysfunction and inner retinal layer thinning in GS.

To evaluate the potential beneficial and synergistic effects of oral intake of a fixed combination of citicoline 500 mg plus homotaurine 50 mg (CIT/HOMO) on retinal ganglion cell (RGC) function in subjects with glaucoma using pattern electroretinogram (PERG) and to investigate the effects on visual field and quality of life. Consecutive patients with primary open-angle glaucoma with controlled IOP (<18 mmHg) receiving beta-blockers and prostaglandin analogs alone or as combination therapy (fixed or un-fixed); with stable disease (progression no more than -1 dB/year at the visual field MD); and an early to moderate visual field defect (MD < -12 dB) were randomized to: arm A. topical therapy + CIT/HOMO for 4 months, 2 months of wash out, 4 months of topical therapy alone; arm B. topical therapy alone for 4 months, topical therapy + CIT/HOMO for 4 months, 2 months of wash out. All patients underwent 4 visits: complete ocular examination, visual field, PERG and quality of life assessment (NEI-VFQ25) were performed at each visit. Fifty-seven patients completed the study: 26 in group A and 31 in group B. At the end of the intake period, PERG's P50 and N95 waves recorded a greater amplitude. The increase was statistically significant in the inferior and superior P50 waves amplitude: 0.47 μV (95%CI, 0.02-0.93; = 0.04) and 0.65 μV (95% CI, 0.16-1.13; = 0.009), respectively, and in the inferior N95 wave amplitude 0.63 μV (95% CI, 0.22-1.04; = 0.002). A significantly shorter peak time of 3.3 μV (95% CI, -6.01- -0.54; = 0.01) was observed for the superior P50 wave only. Daily oral intake of the fixed combination CIT/HOMO for 4 months improved the function of inner retinal cells recorded by PERG in the inferior and in the superior quadrants, independently from IOP reduction. This interesting association could represent a valid option for practicing neuromodulation in patients with glaucoma to prevent disease progression.

Steady-state pattern electroretinogram (PERG) and frequency doubling technology (FDT) perimetry can be used to selectively investigate the activity of the M-Y ganglion cells in adult anisometropic amblyopes. Fifteen normal subjects (mean 27.8±4.1 years) and 15 adults with anisometropic amblyopia (mean 28.7±5.9 years) were analyzed using steady-state PERG and FDT. The amplitude of steady-state PERG was significantly different not only among the control group and both the amblyopic eye ( =0.0001) and the sound eye group ( =0.0001), but also between the latter two groups ( =0.006). The difference in FDT mean deviation was statistically significant not only between the control group and amblyopic eye group ( =0.0002), but also between the control group and the sound eye group ( =0.0009). The FDT pattern standard deviation was significantly higher in the control group rather than in the amblyopic eye ( =0.0001) or the sound eye group ( =0.0001). A correlation was found between the reduction in PERG amplitude and the increase in FDT-pattern standard deviation index not only in amblyopic ( =0.0025) and sound ( =0.0023) eyes, but also in the healthy control group ( =0.0001). These data demonstrate that in anisometropic amblyopia, there is an abnormal functionality of a subgroup of the magnocellular ganglion cells (M-Y), and the involvement of these cells, together with the parvocellular pathway, may play a key role in the clinical expression of the disease.

Purpose As part of a long-term, prospective study of prenatal and clinical risk factors for optic nerve hypoplasia (ONH) at Children’s Hospital Los Angeles, pattern ERGs (PERGs) were evaluated for prognostic value using an automated objective and robust analytical method. Methods Participants were 33 children with ophthalmoscopically diagnosed ONH [disc diameter-to-disc macula ratio (DD/DM) less than 0.35 in one or both eyes on fundus photographs]. Using cycloplegia and chloral hydrate sedation in one session before 26 months of age, we recorded PERGs to checkerboard reversal using five check sizes. Participants were followed with clinical and psychometric testing until 5 years of age. PERGs were analysed using automated robust statistics based on magnitude-squared coherence and bootstrapping optimized to objectively quantify PERG recovery in the challenging recordings encountered in young patients. PERG measures in the fixating or better-seeing eyes were compared with visual outcome data. Results PERG recording was complete to at least three check sizes in all eyes and to all five sizes in 79%. Probability of recording a PERG that is significantly different from noise varied with check size from 73% for the largest checks to 30% for the smallest checks ( p  = 0.002); smaller waveforms were associated with earlier implicit times. The presence of significant PERGs in infancy is associated with better visual outcomes; the strongest association with visual outcome was for the threshold check size with a significant N95 component ( ρ  = 0.398, p  = 0.02). Conclusions Automated statistically robust signal-processing techniques reliably and objectively detect PERGs in young children with ONH and show that congenital deficits of retinal ganglion cells are associated with diminished or non-detectable PERGs. The later negativity, N95, was the best indicator of visual prognosis and was most useful to identify those with good visual outcomes (≤0.4 LogMAR). Although PERGs reflect function of the inner layers of the central retina, they lack the specificity required to determine prognosis reliably in individual cases.

A large cohort of patients participated in a longitudinal study of early glaucoma progression. During follow up, six eyes of three patients displayed a relatively rapid deterioration of pattern electroretinogram (PERG) signal compared to changes in visual acuity, IOP, Standard Automated Perimetry, and Retinal Nerve Fiber Layer thickness measured by OCT. This deterioration prompted further testing including magnetic resonance imaging (MRI), which revealed pituitary tumors in all three patients, two of which were abutting but not compressing the chiasm. Following tumor resection, the PERG signal gradually recovered to baseline values in all six eyes. Results indicate that pituitary tumors may cause retrograde dysfunction of retinal ganglion cells (RGC) even in the absence of visible mechanical compression of the visual pathway, and such dysfunction may be reversed by tumor reduction. The results suggest that PERG is a useful tool in the early diagnosis and management of patients with chiasmal mass lesions.

The present report addresses the electrical activity of the frog retina assessed using electroretinogram (ERG) recordings of responses to instantaneous changes from a reference line stimulus with fixed luminance and orientation to a test stimulus consisting of a line of different luminance and orientation. The analysis revealed two types of retinal responses. Responses to onset and offset of the line stimulus were analogous to responses obtained by homogeneous illumination of the retina and were characterized by a high-amplitude b wave (hundreds of microvolts) and significant asymmetry between the b and d waves. At the same time, interaction of these two stimuli yielded more symmetrical b and d waves, with amplitudes an order of magnitude lower, such that this frog retinal activity approached the ERG pattern recorded in response to formed stimuli in higher vertebrates. Analysis of the interaction of the mechanisms detecting the luminance and configurative characteristics of the stimuli, based on construction of V-shaped discrimination functions, showed that when the luminance of the stimulus line was only slightly different from the luminance of the reference line (i.e., discrimination occurred in the retinal stimulus adaptation zone), the activities of the luminance and orientation channels were summed in the ERG. This indicates that these mechanisms function independently and in parallel. From the moment at which the test stimulus luminance became twice that of the reference stimulus, the increase in ERG amplitude grew in a non-linear manner. This two-stage change in amplitude is explained by the existence of two luminance encoding mechanisms in the frog retina, acting simultaneously with the orientation encoding mechanism. One luminance mechanism encodes the action of the stimulus as the discharge power, generating information encoding the absolute level of environmental illumination. The activity of this mechanism is determined mainly by receptors and cells in the outer plexiform layer of the retina. The other mechanism is based on vector encoding of stimulus actions, generating information encoding the spatial and temporal differentiation of light in the visual field and is mainly associated with cells in the inner plexiform layer of the retina.

To optimize the simultaneous recording of retinal and cortical potentials, we tried to identify the most sensitive condition for pattern-electroretinogram (PERG) and pattern visual evoked potential (VEP) concerning the temporal frequency. In the same session PERGs and VEPs were elicited by checkerboard patterns with 5 temporal frequencies ranging from 8 rps to 33 rps. For data analysis the steady-state responses were Fourier analysed. We evaluated whether a statistically significant response was present, estimated the magnitude of the response at the stimulus frequencies tested and estimated it's significance. For PERG less dependence on temporal frequency was evident compared to VEP. The magnitude of the VEP response was larger than that of the PERG. However the rate of statistically significant responses for the PERG compared to that of the VEP was similar for the small checksize and even higher for the large checksize. The results permit a simultaneous recording in the range of temporal frequencies, where high responses are acquired from both levels, retinal and cortical.

The pattern electroretinogram (PERG) is a localized retinal response evoked by a contrast-reversing pattern, usually a black and white checkerboard, which provides information about macular and retinal ganglion cell function. This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV; www.iscev.org) presents an updated and revised Standard for clinical PERG testing. This replaces the 2013 and all earlier versions. Minimum protocols for basic PERG stimuli, recording methods and reporting are specified, to promote consistency of methods for diagnosis and monitoring purposes, while responding to evolving clinical practices and technology. The main changes in the updated ISCEV Standard for clinical PERG include expanded guidance about large stimulus fields, stimulus parameters for simultaneous PERG and pattern visual evoked potential recording, baseline drift correction, and use of consistent ambient room lighting. These changes aim to provide a clinically relevant document about current practice which will facilitate good quality recordings and inter-laboratory comparisons.

PurposeThe steady-state pattern electroretinogram (ssPERG) is used to assess retinal ganglion cell function in a variety of research contexts and diagnostic applications. In certain groups of patients or study participants, stable central fixation of the stimulus is not guaranteed. The present study aimed at assessing the effects of misfixation on the ssPERG response to checkerboard reversal stimuli.MethodsUsing two check sizes (0.8° and 15°), we compared ssPERG responses for several amounts of fixation deviation, ranging from 0° to 19° horizontally and from 0° to 14° diagonally. The stimulus area extended to 15° eccentricity, stimulus reversal rate was 15/s.ResultsUp to around 7° eccentricity, there was no sizable effect of fixation deviation under most conditions. Effects were somewhat larger for nasal than for temporal deviation, in particular for small checks. Diagonal deviation was associated with a response to luminance onset/offset at 7.5 Hz (subharmonic of the reversal rate), most prominently when the interior of a large check was fixated.ConclusionGenerally, moderate inaccuracies of fixation do not have a sizable effect on ssPERG amplitude. However, with large checks, the luminance response has to be considered.