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Pattern visual evoked potentials (pattern VEP) are widely used for functional assessment of the visual pathways. The P100 component represents the principal clinical parameter owing to its relative interindividual stability and diagnostic value. However, both latency and amplitude are modulated by multiple physiological and environmental factors, which complicates interpretation and the establishment of reliable reference standards. This scoping review aimed to systematically map determinants of P100 parameters in healthy individuals. The review was conducted in accordance with PRISMA-ScR and Joanna Briggs Institute methodology. Databases were searched for studies published between 2015 and 2025 that examined biological, refractive, anthropometric, metabolic, or environmental influences on pattern VEP parameters in healthy populations. Owing to methodological heterogeneity, findings were synthesized descriptively. Thirty-nine studies met the inclusion criteria. Age emerged as the most consistent determinant of P100 parameters. Latency followed a non-linear trajectory across the lifespan, with shortening during maturation, stabilization in early adulthood, and progressive prolongation after approximately 40 years of age, whereas amplitude generally declined with aging. Sex differences predominantly affected amplitude, with women typically demonstrating higher P100 or N75-P100 amplitudes in adult populations; latency differences were less consistent and often minimal in paediatric cohorts. Retinal image quality exerted a strong dose-dependent effect on P100 parameters: increasing refractive blur and higher-order aberrations were associated with progressive latency prolongation and amplitude reduction, particularly for small check sizes. Ocular dominance showed no clinically meaningful interocular asymmetry. Metabolic disturbances were associated with prolonged latency in selected populations, whereas anthropometric variables such as head size and height demonstrated weak or inconsistent associations. Among environmental factors, acute alcohol intake prolonged P100 latency, while moderate caffeine consumption had no significant effect. Age and retinal image quality represent the primary physiological determinants of P100 latency and amplitude in healthy individuals. Most other modifiers exert modest or context-dependent effects. Consideration of these variables is essential for accurate interpretation of pattern VEP recordings and for establishing reliable local reference standards consistent with ISCEV recommendations.

To investigate the difference in preoperative retinal function in patients with type 2 diabetes cataract (DC) without obvious retinopathy and to explore the clinical application of full blood glucose management for improving the postoperative vision in DC patients. This was a retrospective analysis in which we estimated the changes in visual electrophysiology (N75, P100, photopic flash electroretinogram(FERG), and scotopic FERG, paraoptic retinal nerve fibre layer thickness (pRNFL) and paraoptic radial capillary network blood flow density (ppVD) of type 2 diabetes (T2DM) patients at different phases of disease progression along with fasting blood glucose (FBG) and glycosylated haemoglobin (HbAlC) levels before and after DC surgery at Ziyang Central Hospital from January 2020 to December 2022. Additionally, trends in the above data throughout the entire process of glucose management intervention were examined. As the course of T2DM progressed, FBG and HbA1c increased, the N75 and P100 latency periods of patients gradually increased, and the values of photopic FERG, scotopic FERG, pRNFL, and ppVD gradually decreased at each postoperative time point. Moreover, the best corrected visual acuity(BCVA) of patients after surgery gradually decreased ( P  < 0.05). The BCVA of Group B (with full process blood glucose management) gradually stabilized at 1 month after surgery, and the BCVA of Group B was better than that of Group A at all time points after surgery. The results revealed that N75 and P100 in Group A were greater than those in Group B, whereas the photopic and scotopic FERG, pRNFL, and ppVD (%) values in Group A were lower than those in Group B. In addition, N75 and P100 in Group A gradually increased at various time points after surgery, whereas the photopic FERG, scotopic FERG, pRNFL, and ppVD (%) values gradually decreased. In the state of full blood glucose management, although N75 and P100 both reached their longest durations at one week after surgery, N75, the P100, photopic FERG, scotopic FERG, and pRNFL showed a gradually decreasing trend at 1 month and 3 months after surgery, whereas ppVD (%) gradually increased ( P  < 0.05). According to the results of the quantitative analysis of visual electrophysiology and OCTA, with the aggravation of diabetes, the retinal function of DC patients without obvious retinopathy tends to decrease, but full-process blood glucose management can effectively recover the retinal function of DC patients and improve visual quality after surgery.

PurposeVisual outcomes after cataract surgery in diabetic patients with retinal or visual pathway disease are difficult to predict as the fundus may be obscured, and assessment of visual potential is challenging. This study assessed the value of visual electrophysiology as a prognostic indicator of visual recovery in diabetic patients with cataract, prior to cataract surgery.MethodsForty-one diabetic patients (aged 52–80; 74 eyes) and 13 age-matched non-diabetic control patients (21 eyes) were examined prior to cataract surgery. Pre-surgical examinations included best-corrected visual acuity (BCVA), slit-lamp bio-microscopy, ISCEV-standard full-field electroretinography (ffERG), and flash visual evoked potential (flash VEP) testing. Electrophysiological assessments included quantification of the DA and LA ERG, oscillatory potentials (OPs; OP1, OP2, OP3, OP4) and flash VEP P1, P2, and P3 components. Post-operative BCVA was measured in all cases and the diabetic patients grouped according to the severity of visual acuity loss: mild (logMAR ≤ 0.1), moderate (0.1 < logMAR < 0.5), or severe (logMAR ≥ 0.5). A fourth group included those without diabetes. The pre-surgical electrophysiological data was compared between the four groups by analysis of variance.ResultsThe severity of post-surgical visual acuity loss in the diabetic patients was classified as mild (N=22 eyes), moderate (N=31 eyes), or severe (N=21 eyes). In the group without diabetes, post-surgical visual impairment was classified as mild (N=21 eyes). The pre-operative DA 10.0 ERG a-wave amplitudes, DA 3.0 ERG OP2 amplitudes, and the LA 3.0 a- and b-wave amplitudes showed best significant differences among the four groups. The flash VEP did not show significant difference between groups.ConclusionElectrophysiological assessment of diabetic patients with cataract can provide a useful measure of retinal function. Full-field ERG components, including the DA 10.0 ERG a-wave, DA 3.0 ERG OP2 component, and the LA 3.0 a- and b-wave amplitudes, are of prognostic value in predicting post-surgical visual acuity, and may inform the surgical management of cataract patients with diabetes.

Purpose To introduce ERGtools2, an open-source R package for processing, analysing and long-term storing visual electrophysiology data. Methods A dataset comprising Electroretinogram (ERG) recordings of C57Bl/6J mice, subjected to standard ISCEV stimuli, was used to present the functionality of ERGtools2. ERGtools2 stores and organizes all recordings, metadata, and measurement information from an individual examination in a single object, maintaining raw data throughout the analysis process. Results A standard workflow is presented exemplifying how ERGtools2 can be used to efficiently import, pre-process and analyse ERG data. Following this workflow, basic ERG measurements and visualisation of a single exam as well as group statistics are obtained. Moreover, special use cases are described, including for the handling of noisy data and the storage of data in the HDF5 format to ensure long-term preservation and accessibility. Conclusions ERGtools2 provides a comprehensive, flexible, and device-independent solution for visual electrophysiology data analysis. Its emphasis on maintaining raw data integrity, combined with advanced processing and analysis capabilities, makes it a useful tool for preclinical and clinical research applications. The open-source nature and the use of open data formats promote reproducibility and data sharing in visual neurosciences.

This study investigated the relationships between structural and functional parameters in non-arteritic ischemic optic neuropathy (NAION). This retrospective study enrolled 29 patients (58.2 ± 10.4 years old) with unilateral NAION. During the acute phase, we performed comprehensive evaluations including best-corrected visual acuity (BCVA), optical coherence tomography (OCT), optical coherence tomography angiography (OCTA), visual fields (VF), visual evoked potentials (VEP), electroretinography (ERG), and multifocal ERG (mf-ERG). At three months post-presentation, patients underwent follow-up assessments comprising visual acuity testing, perimetry, and advanced retinal imaging. During the acute phase, affected eyes demonstrated increased mean retinal nerve fiber layer (RNFL) thickness, while ganglion cell-inner plexiform layer (GCIPL) thickness decreased. Both visual fields mean deviation (MD) and VEP P100 amplitude were reduced, accompanied by prolonged peak latency. We also observed decreased P1 response density in mf-ERG. Analysis revealed significant direct correlations between GCIPL parameters and electrophysiological measurements, particularly VEP P100 amplitude and mf-ERG P1 response density. Mean GCIPL thickness, VF MD, and VEP P100 amplitude showed negative correlations with baseline logMAR VA. Baseline VF MD, VEP P100 amplitude, and minimum GCIPL thickness showed negative correlations with logMAR VA at 3-month follow-up. Retinal ganglion cell layer thickness serves as a valuable indicator to objective evaluate optic nerve function in acute NAION patients. Decreases in both VEP amplitude and mf-ERG response density showed significant correlations with retinal ganglion cell layer thickness. Baseline visual field performance, VEP measurements, and minimum GCIPL thickness exhibited negative correlations visual acuity at 3-month follow-up. Clinical Research Ethics Committee of Xi'an People's Hospital (NO. 20220018). Registered 27 September 2022-Retrospectively registered, https://www.medicalresearch.org.cn/. Informed consent was obtained from each participant.

Introduction Pseudoisochromatic stimuli are widely used in psychophysical color vision testing and the features of the luminance noise present on these stimuli have been reported modifying the psychophysical chromatic discrimination. Objective The present study investigated how modifications in the luminance noise features (luminance contrast and number of luminance values) affect chromatic visual evoked cortical potentials (VECP) elicited by pseudoisochromatic gratings, aiming to evaluate the influence of luminance contrast and the number of luminance values in the pseudoisochromatic stimulus on the chromatic VECP. Methods The sample consisted of seven young trichromatic participants. The waveforms of the visual evoked cortical potentials (VECP) were analyzed, focusing on the P1, N1, and P2 components across all stimulus conditions. The luminance noise contrast in the pseudoisochromatic stimulus had distinct effects on the amplitudes of the VECP components. Significant effects were observed for the amplitudes of the P1 ( p = 0.01) and P2 ( p = 0.04) components, while no significant effect was found on the amplitude of the N1 component ( p = 0.3). Results There was no significant effect of the luminance noise range on the latency of the VECP components (P1 VECP component, p = 0.54; N1 VECP component, p = 0.79; P2 VECP component, p = 0.49). The number of luminance values in the noise had no significant effect on VECP components amplitude and latency. Different manipulations of luminance noise influenced P1 and P2 VECP components and no modification of the luminance noise had influence on the main chromatic VECP component, N1 component. Conclusion Manipulations in features of the luminance noise in pseudoisocrhomatic stimulus impacted in putative luminance components, but not chromatic components, of visual evoked potentials. The present findings may have potential applications in clinical neuro-ophthalmology, particularly for assessing congenital and acquired color blindness.

The aim of this study was to investigate the use of inexpensive and easy-to-use hydrogel “marble” electrodes for the recording of electrical potentials of the human visual cortex using visual evoked potentials (VEPs) as example. Top hat-shaped holders for the marble electrodes were developed with an electrode cap to acquire the signals. In 12 healthy volunteers, we compared the VEPs obtained with conventional gold-cup electrodes to those obtained with marble electrodes. Checkerboards of two check sizes—0.8° and 0.25°—were presented. Despite the higher impedance of the marble electrodes, the line noise could be completely removed by averaging 64 single traces, and VEPs could be recorded. Linear mixed-effect models using electrode type, stimulus, and recording duration revealed a statistically significant effect of the electrode type on only VEP N75 peak latency (mean ± SEM: 1.0 ± 1.2 ms) and amplitude (mean ± SEM: 0.8 ± 0.9 µV) The mean amplitudes of the delta, theta, alpha, beta, and gamma frequency bands of marble electrodes were statistically significantly different and, on average, 25% higher than those of gold-cup electrodes. However, the mean amplitudes showed a statistically significant strong correlation (Pearson’s r = 0.8). We therefore demonstrate the potential of the inexpensive and efficient hydrogel electrode to replace conventional gold-cup electrodes for the recording of VEPs and possibly other recordings from the human cortex.

PurposeThe aim of this study was to develop a simple and reliable method for the objective assessment of visual acuity by optimizing the stimulus used in commercially available systems and by improving the methods of evaluation using a nonlinear function, the modified Ricker model.MethodsSubjective visual acuity in the normal subjects was measured with Snellen targets, best-corrected, and in some cases also uncorrected and with plus lenses (+ 1 D, + 2 D, + 3 D). In patients, subjective visual acuity was measured best-corrected using the Freiburg Visual Acuity Test. Sweep VEP recordings to 11 spatial frequencies, with check sizes in logarithmically equidistant steps (0.6, 0.9, 1.4, 2.1, 3.3, 4.9, 7.3, 10.4, 18.2, 24.4, and 36.5 cpd), were obtained from 56 healthy subjects aged between 17 and 69 years (mean 42.5 ± 15.3 SD years) and 20 patients with diseases of the lens (n = 6), retina (n = 8) or optic nerve (n = 6). The results were fit by a multiple linear regression (2nd-order polynomial) or a nonlinear regression (modified Ricker model) and parameters compared (limiting spatial frequency (sflimiting) and the spatial frequency of the vertex (sfvertex) of the parabola for the 2nd-order polynomial fitting, and the maximal spatial frequency (sfmax), and the spatial frequency where the amplitude is 2 dB higher than the level of noise (sfthreshold) for the modified Ricker model.ResultsRecording with 11 spatial frequencies allows a more accurate determination of acuities above 1.0 logMAR. Tuning curves fitted to the results show that compared to the normal 2nd-order polynomial analysis, the modified Ricker model is able to describe closely the amplitudes of the sweep VEP in relation to the spatial frequencies of the presented checkerboards. In patients with a visual acuity better than about 0.5 (decimal), the predicted acuities based on the different parameters show a good match of the predicted visual acuities based on the models established in healthy volunteers to the subjective visual acuities. However, for lower visual acuities, both models tend to overestimate the visual acuity (up to ~ 0.4 logMAR), especially in patients suffering from AMD.ConclusionsBoth models, the 2nd-order polynomial and the modified Ricker model performed equally well in the prediction of the visual acuity based on the amplitudes recorded using the sweep VEP. However, the modified Ricker model does not require the exclusion of data points from the fit, as necessary when fitting the 2nd-order polynomial model making it more reliable and robust against outliers, and, in addition, provides a measure for the noise of the recorded results.

Albinism describes a heterogeneous group of genetically determined disorders characterized by disrupted synthesis of melanin and a range of developmental ocular abnormalities. The main ocular features common to both oculocutaneous albinism (OCA), and ocular albinism (OA) include reduced visual acuity, refractive errors, foveal hypoplasia, congenital nystagmus, iris and fundus hypopigmentation and visual pathway misrouting, but clinical signs vary and there is phenotypic overlap with other pathologies. This study reviews the prevalence, genetics and ocular manifestations of OCA and OA, including abnormal development of the optic chiasm. The role of visual electrophysiology in the detection of chiasmal dysfunction and visual pathway misrouting is emphasized, highlighting how age-associated changes in visual evoked potential (VEP) test results must be considered to enable accurate diagnosis, and illustrated further by the inclusion of novel VEP data in genetically confirmed cases. Differential diagnosis is considered in the context of suspected retinal and other disorders, including rare syndromes that may masquerade as albinism.

PurposeTo investigate the magnitude and time course of pseudorandom ffERG during light adaptation.MethodsTen healthy subjects (26 ± 10.1 years) underwent 20 min of dark adaptation, and then the ffERG was evoked by pseudorandom flash sequences (4 ms per flash, 3 cd.s/m2) driven by m-sequences (210–1 stimulus steps) using Veris Science software and a Ganzfeld dome over a constant field of light adaptation (30 cd/m2). The base period of the m-sequence was 50 ms. Each stimulation sequence lasting 40 s was repeated at 0, 5, 10, 15 and 20 min of light adaptation. Relative amplitude and latency (corrected by values found at 0 min) of the three components (N1, P1, and N2) of first-order (K1) and first slice of the second-order (K2.1) kernel at 5 time points were evaluated. An exponential model was fitted to the mean amplitude and latency data as a function of the light adaptation duration to estimate the time course (τ) of the light adaptation for each component. Repeated one-way ANOVA followed by Tukey post-test was applied to the amplitude and latency data, considering significant values of p < 0.05.ResultsRegarding the K1 ffERG, N1 K1, P1 K1, and N2 K1 presented an amplitude increase as a function of the light adaptation (N1 K1τ value = 2.66 min ± 4.2; P1 K1τ value = 2.69 min ± 2.10; and N2 K1 τ value = 3.49 min ± 2.96). P1 K1 and N2 K1 implicit time changed as a function of the light adaptation duration (P1 K1τ value = 3.61 min ± 5.2; N2 K1τ value = 3.25 min ± 4.8). N1 K1 had small implicit time changes during the light adaptation. All the K2,1 components also had nonsignificant changes in amplitude and implicit time during the light adaptation.ConclusionsPseudorandom ffERGs showed different mechanisms of adaptation to retinal light. Our results suggest that K1 ffERG is generated by retinal mechanisms with intermediate- to long-term light adaptation, while K2.1 ffERG is generated by retinal mechanism with fast light adaptation course.