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Purpose: To investigate the effect of Ozurdex (dexamethasone intravitreal implant) on multifocal electroretinography (mfERG) findings during the treatment of macular edema secondary to the central retinal vein occlusion (CRVO). Methods: Fifteen eyes of 15 patients who were treated with Ozurdex implant due to CRVO-related macular edema were included in this study. Best corrected visual acuity (BCVA), central macular thickness (CMT), and mfERG evaluations were performed for all patients before injection of Ozurdex. After the injection, BCVA and CMT were measured at months 3 and 6 and mfERG test was performed at month 6 for all patients. Results: Pre-implantation mfERG P wave amplitude values of r1, r2, r3, r4 and r5 were 57.8 ± 14.8, 25.1 ± 10.6, 17.2 ± 7.3, 12.0 ± 5.0 and 7.1 ± 3.6 nV/deg2, respectively. They increased to 72.9 ± 33.2, 31.2 ± 9.3, 22.6 ± 7.6, 15.6 ± 7.1 and 10.9 ± 5.7 nV/deg2, respectively, at month 6. However, these increases were not statistically significant (all P > 0.05). Pre-implantation mfERG r1, r2, r3, r4 and r5 P wave implicit times were 40.1 ± 10.9, 39.4 ± 3, 38.4 ± 3.4, 38.2 ± 3.1 and 39.3 ± 2.2 ms, respectively and these values were measured as 38.9 ± 8.2, 38.4 ± 4.7, 37 ± 3.8, 37.5 ± 4.6 and 37.7 ± 4.7 ms at 6 months. Although there were reductions in P wave implicit times in all rings, they were not statistically significant (all P > 0.05). Conclusion: In this prospective study, we found that the Ozurdex implant had no effect on mfERG findings 6 months after insertion for treatment of CRVO-related macular edema.

To investigate changes in multifocal electroretinography (mfERG) parameters associated with high dose chloroquine therapy for treatment of malaria in the Amazonia region of Brazil. Forty-eight subjects who had received chloroquine treatment for single or multiple malaria infections with a cumulative dose ranging from 1,050 to 27,000mg were included. The control group consisted of 37 healthy aged-matched subjects. Data was collected on amplitude and implicit time of the N1, P1 and N2 waves in the central macular hexagon (R1) and in five concentric rings at different retinal eccentricities (R2-R6). No significant difference was observed in any mfERG parameter between chloroquine treated patients and control subjects. A comparison with previous data obtained from patients with rheumatologic disorders in the same region of Brazil who had received larger cumulative doses of chloroquine and had displayed mfERG changes, indicated that retinal toxicity seems to be dependent on cumulative dose. Lack of mfERG changes in the current study suggests that intensive high dose chloroquine therapy for treatment of malaria is not associated with retinal toxicity.

Visual electrophysiology is a valuable tool for evaluating the visual system in various systemic syndromes. This review highlights its clinical application in a selection of syndromes associated with hearing loss, mitochondrial dysfunction, obesity, and other multisystem disorders. Techniques such as full-field electroretinography (ffERG), multifocal electroretinography (mfERG), pattern electroretinography (PERG), visual evoked potentials (VEP), and electrooculography (EOG) offer insights into retinal and optic nerve function, often detecting abnormalities before clinical symptoms manifest. In hearing loss syndromes like Refsum disease, Usher syndrome (USH), and Wolfram syndrome (WS), electrophysiology facilitates the detection of early retinal changes that precede the onset of visual symptoms. For mitochondrial disorders such as maternally-inherited diabetes and deafness (MIDD), Kearns–Sayre syndrome (KSS), and neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome, these tests can be useful in characterizing retinal degeneration and optic neuropathy. In obesity syndromes, including Bardet-Biedl syndrome (BBS), Alström syndrome, and Cohen syndrome, progressive retinal degeneration is a hallmark feature. Electrophysiological techniques aid in pinpointing retinal dysfunction and tracking disease progression. Other syndromes, such as Alagille syndrome (AGS), abetalipoproteinemia (ABL), Cockayne syndrome (CS), Joubert syndrome (JS), mucopolysaccharidosis (MPS), Neuronal ceroid lipofuscinoses (NCLs), and Senior–Løken syndrome (SLS), exhibit significant ocular involvement that can be evaluated using these methods. This review underscores the role of visual electrophysiology in diagnosing and monitoring visual system abnormalities across a range of syndromes, potentially offering valuable insights for early diagnosis, monitoring of progression, and management.

[This corrects the article DOI: 10.3389/fmed.2025.1528104.].

INTRODUCTION: We aimed to demonstrate probable neuronal benefits derived from glycemic control in diabetic patients without diabetic retinopathy (DRP) by using multifocal electroretinography (mfERG). METHODS: Forty patients with HbA1c level >8% were included in this study. Baseline mfERG measurement (first kernel order) of patients were done. The study group consisted of patients existed 1 unit decrease in HbA1c relative to baseline and the control group consisted of patients with an insufficient decrease (n=16). The control mfERG measurements of the study group were done after HbA1c decrease is obtained (mean 13.6 months) and in the first year follow-up in the control group. RESULTS: Baseline HbA1c level was 8.7+-0.6 in the study group and 8.4+-0.5 in the control group and the levels were 7.5+-0.5 and 8.35+-0.4 respectively after glycemic control. Decrease of HbA1c levels in the study group was significant. Comparing baseline and follow up measurements the difference between P1 and N1 wave amplitude and implicit time values weren't statistically significant in the study group in which glycemic control was good relative to baseline. DISCUSSION AND CONCLUSION: We have determined no significant changes in mfERG parameters after approximately 1 year follow up in both good and insufficient glycemic control groups. The reasons for this could be the progression of retinopathy in diabetic patients despite glycemic control or inadequacy of first kernel orders in revealing functions of inner retina layers.

Background: This study evaluated morphological and functional differences among eyes with retinitis pigmentosa (RP) classified according to fundus autofluorescence (FAF) patterns. Methods: A total of 146 eyes from 73 patients with RP were analysed. Based on FAF imaging, eyes were classified as having regular hyperautofluorescent rings (n = 23), irregular rings (n = 76), or absent rings (n = 47). Participants underwent best-corrected visual acuity (BCVA), contrast sensitivity, 10–2 and 30–2 static perimetry, multifocal electroretinography (mfERG), and optical coherence tomography (OCT). FAF morphometrics included ring diameters and area. Results: Eyes with a regular FAF ring demonstrated significantly better visual function than those with irregular or absent rings, including higher BCVA (p < 0.001 and p = 0.001) and greater contrast sensitivity (both p < 0.001). The mfERG amplitude density in the first ring was higher in regular than irregular FAF patterns (p = 0.034). Eyes with irregular FAF showed more advanced visual field loss, with lower mean deviation on 10–2 (p = 0.042) and 30–2 perimetry (p = 0.027). In the regular-ring group, the ellipsoid zone was predominantly intact (p = 0.012). The hyperautofluorescent ring area correlated positively with mfERG amplitude density in the first and second rings (Rs = +0.573, p = 0.016; Rs = +0.736, p = 0.001) and with macular volume (Rs = +0.667, p = 0.003). Conclusions: FAF patterns reflect central retinal functional and structural impairment in RP. Therefore, incorporating FAF imaging into the diagnostic algorithm is valuable for monitoring disease progression.

PurposeTo identify whether there are functional abnormalities in the retina of amblyopic eyes using multifocal electroretinography (mfERG).MethodsThis is a prospective study of patients ≥ 7 years of age identified with unilateral amblyopia (strabismic or anisometropic). Multifocal ERG and flash ERG were performed to compare parameters between the amblyopic and non-amblyopic fellow eyes. A complete analysis of the five ring averages was done including the central ring.ResultsThirty-eight patients were included: mean age was 14.3 ± 7.3 years; 18 patients were strabismic and 20 were anisometropic. Amblyopic eye responses across the rings in multifocal ERG were diminished compared with fellow non-amblyopic eyes with significant differences detected in the central rings (p = 0.001). On the other hand, flash ERG did not show any consistently significant differences. When divided by severity, amplitudes of central rings were significantly lower in severely amblyopic eyes compared with non-amblyopic eyes (p = 0.001), while in mild amblyopia, no significant differences were observed. No significant difference was observed between anisometropic and strabismic amblyopic eyes.ConclusionsUsing multifocal ERG, significantly decreased amplitudes were observed in amblyopic eyes compared with normal fellow eyes in the central ring. This correlated with the severity of amblyopia. No difference was observed when comparing the two groups of amblyopia (strabismic and anisometropic). Those findings may help clarify the pathophysiology of amblyopia better and open the door for new objective ways to monitor the response to amblyopia treatment but this needs to be further studied.

PurposeTo examine (1) the retinal structure by optical coherence tomography (OCT) and function by means of multifocal electroretinography (mfERG) in eyes with and without nonproliferative diabetic retinopathy (NPDR) (2) for correspondence between local retinal function and OCT zones with retinal lesions.MethodsOne hundred and thirty-two eligible participants (30 with nonproliferative DR (NPDR) and 102 with diabetes with no DR) underwent comprehensive ophthalmic examination, optical coherence tomography for retinal thickness measures, mfERG, and ultra-wide field fundus photography. OCT Early Treatment Diabetic Retinopathy Study (ETDRS) grid was overlaid on to mfERG plots.ResultsThose with NPDR had significantly thicker full retinal measures in the nine (ETDRS) zones compared to no DR. mfERG P1 latencies in rings 1–6 were significantly delayed, while the response densities in rings 4–6 were lower in the NPDR group. Significant negative correlation was noted between OCT thickness and mfERG P1 response densities in many ETDRS zones. Significant positive correlation was noted between P1 latencies and OCT thickness in a few zones. The combination of cystic spaces, microaneurysms, and hard exudates were present in all zones and were associated with a decrease in P1 response densities compared to no lesions. Reduced P1 response densities were associated with a sporadic delay in the mfERG latencies and vice versa. The number of lesions did not show correspondence to the mfERG measures.ConclusionsIn eyes with NPDR, retinal function is differentially correlated with the DR lesions on OCT and can be assessed using multimodal imaging modalities.

Purpose It is established that the mfERG is altered in type 2 diabetes (T2DM). The P1 implicit time (IT) becomes delayed even before retinopathy is present. This has been associated with the duration of damage to retinal cells from hyperglycemia. However, patients withT2DM and prediabetes also have changes in insulin values. The impact of elevated or reduced blood insulin on retinal function using mfERG has not been explored. Here we evaluate the the relationship between blood insulin levels and mfERG parameters in patients with and without T2DM and prediabetes. Methods 66 subjects (age 50.4 ± 10.5) were included in this cross-sectional study. Subjects were asked if fasted upon presentation. HbA1c was taken and used to categorize subjects into groups as controls (< 5.7%), prediabetes (5.7–6.4%) or T2DM (> 6.4% or previously diagnosed). Insulin was collected from finger stick and was analyzed via ELISA. A mfERG (103 hexagons) was performed (VERIS 6.3) with 4-min m-sequence at near 100% contrast. Data was evaluated for ring hexagons, as well as averaged together for P1 IT. No subjects had retinopathy or were taking exogenous insulin. Data were evaluated through ANOVA for comparisons of groups and as well as with multivariate regression analysis. Results There was a strong positive correlation between fasting blood glucose and mfERG IT ( P  < 0.002) in all subjects. There was also a negative relationship between averaged mfERG IT and fasted blood insulin concentration ( P  = 0.035) after age, T2DM duration and blood glucose were controlled for in a multivariate regression. There was a significant difference in mfERG IT between the groups ( p  = 0.008) with T2DM exhibiting the longest IT, but no difference between controls and prediabetes. There was no difference in insulin levels between groups, nor were there any significant relationships between insulin and mfERG IT for those who were not fasted. Conclusions Reduced blood insulin is associated with IT delays under overnight fasted conditions, which suggests a lack of insulin may impair retinal function. Future work should examine these associations of retinal function with insulin under well controlled and standardized postprandial conditions such as during oral glucose tolerance testing.

Purpose: To compare observation versus subthreshold green laser (STL) in acute central serous chorioretinopathy (CSC) in terms of anatomical and functional outcomes. Methods: Prospective randomized interventional study. 30 eyes with the first episode of acute CSC underwent complete ophthalmologic examination, measurement of best-corrected Snellen visual acuity (BCVA), contrast sensitivity (CS), fundus fluorescein angiography (FFA), spectral-domain optical coherence tomography (SD-OCT), and multifocal electroretinography (mfERG) at baseline. Patients were randomized equally to group A (observation) or group B (STL using 532 nm wavelength applied to the leakage point). Outcome measures included BCVA, CS, central foveal thickness (CFT), and mean macular thickness (MMT) on SD-OCT and P1 amplitude and implicit time (IT) on mfERG. Patients were followed up for 6 months. Results: Mean BCVA was comparable between the two groups on follow up; however, mean CS was significantly higher in group B at 6 months (P = 0.032). CFT was significantly lower in group B at 1 month (P = 0.001) and 3 months (P = 0.049); however, this difference was not maintained at 6 months (P = 0.265). P1 amplitude and IT in all 5 rings were comparable between the two groups at baseline. On follow up, P1 amplitude of ring 1 became significantly higher in group B at 3 months (P = 0.036) and 6 months (P = 0.022). Conclusion: Immediate treatment of acute CSC with STL, as compared to conservative management, leads to more rapid resolution on SD-OCT and superior functional outcomes as evidenced by CS and mfERG.