Effects of Smoothing and Adaptive Filtering in Multifocal Electroretinography (mfERG)

(1) Background: mfERG testing is used to study the function of cone photoreceptors in the central retina. Various filters including "smoothing" (Smooth) and "adaptive data filtering" (Adapt) are used to simplify raw data. This study will seek to characterize the effect of data modification on raw patient data. (2) Methods: This was a retrospective study of patients with mfERG results at our institution. For each patient, raw mfERG data without filtering, with smooth level 4 modifier applied, and with adapt level 4 applied were collected and compared. (4) Conclusions: In all patients, smoothing and adaptive filter modifiers create statistically significant differences in both P1 latency and P1 amplitude values when compared to raw data. The impacts of these filters demonstrated in this study should impact physicians' decision making when interpreting mfERG results.

Functional Outcomes and Safety Profile of Trans-Foveal Subthreshold Micropulse Laser in Persistent Central Serous Chorioretinopathy

Our study evaluated visual function changes after subthreshold micropulse laser (SML) treatment in persistent central serous chorioretinopathy (CSC) and SML safety profile. We conducted a prospective study including 31 fovea-involving CSC patients. The natural course was observed for the first 3 months, SML was performed at 3 months, and SML effectiveness was observed at 6 months. At all three clinical visits, optical coherence tomography (OCT), best corrected visual acuity (BCVA), contrast sensitivity (CS) in five spatial frequencies (1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree (cpd)), microperimetry (MP), and multifocal electroretinography (mfERG) were performed. The SML safety profile was evaluated with functional and morphological parameters. In the cohort of all CSC patients treated with SML, the statistically significant average improvement was observed in BCVA (p = 0.007), CS-1.5 (p = 0.020), CS-3.0 (p = 0.050), CS-12.0 (p < 0.001), CS-18.0 (p = 0.002), CS (CS-A) (p < 0.001), MP in the central ring (MP-C) (p = 0.020), peripheral ring (MP-P) (p = 0.042), and average retinal sensitivity (MP-A) (p = 0.010). After the SML treatment, mean changes in mfERG amplitudes and implicit times in our cohort were not statistically significant. No morphological or functional adverse effects of SML treatment were observed. SML treatment in persistent CSC episodes leads to significant functional improvement and has an excellent safety profile.

Modeling of dielectric resonator antenna array for retina photoreceptors

The retina encompasses several cone and rod photoreceptors at fovea region i.e., 90 million cells of rod photoreceptors and 4.5million cells of cone photoreceptors. The overall photoreceptors determine the vision of every human. An electromagnetic dielectric resonator antenna has been presented for retina photoreceptors in order to model them at fovea and its peripheral retina with the respected angular spectrum. Three coloring primary system of human eye (R, G, B) can be realized based on the model. Three miscellaneous models i.e., simple, graphene coated, and interdigital models have been presented in this paper. The nonlinear property of interdigital structures is one of the best advantages to use for creating the capacitor. The capacitance property helps improving the upper band of visible spectrum. The absorption of light for graphene as an energy harvesting material and its conversion into electrochemical signals is making it one of the best models. The mentioned three electromagnetic models of human photoreceptors have been expressed as a receiver antenna. The proposed electromagnetic models based on dielectric resonator antenna (DRA) are being analyzed for cones and rods photoreceptors of retina in the human eye by Finite Integral Method (FIM) utilized by CST MWS. The results show that the models are so fine for vision spectrum due to its localized near field enhancement property. The results indicate fine parameters of S 11 (return loss below -10 dB) with invaluable resonants in a wide range of frequencies from 405 THz to 790 THz (vision spectrum), appropriate S 21 (insertion loss 3-dB bandwidth), very good field distribution of electric and magnetic fields for flowing the power and electrochemical signals. Finally, mfERG clinical and experimental results validate the numeric results by the normalized output to input ratio of these models and it points out that these models can stimulate the electrochemical signals in photoreceptor cells for the best suiting of realizing the new retinal implants.

Comparison of DTL and gold cup skin electrodes for recordings of the multifocal electroretinogram

OBJECTIVE

To compare mfERG recordings with the Dawson-Trick-Litzkow (DTL) and gold cup skin electrode in healthy young and old adults and to test the sensitivity of both electrodes to age-related changes in the responses.

METHODS

Twenty participants aged 20-27 years ("young") and 20 participants aged 60-75 ("old") with a visual acuity of ≤ 0 logMAR were included. The mfERG responses were recorded simultaneously using DTL and skin electrodes. P1 amplitudes, peak times and signal-to-noise ratios (SNRs) were compared between both electrodes and across age groups, and correlation analyses were performed. The electrode's performance in discriminating between age groups was assessed via area under curve (AUC) of receiver operating characteristics.

RESULTS

Both electrodes reflected the typical waveform of mfERG recordings. For the skin electrode, however, P1 amplitudes were significantly reduced (p < 0.001; reduction by over 70%), P1 peak times were significantly shorter (p < 0.001; by approx. 1.5 ms), and SNRs were reduced [(p < 0.001; logSNR ± SEM DTL young (old) vs gold cup: 0.79 ± 0.13 (0.71 ± 0.15) vs 0.37 ± 0.15 (0.34 ± 0.13)]. All mfERG components showed strong significant correlations (R² ≥ 0.253, p < 0.001) between both electrodes for all eccentricities. Both electrodes allowed for the identification of age-related P1 changes, i.e., P1-amplitude reduction and peak-time delay in the older group. There was a trend to higher AUC for the DTL electrode to delineate these differences between age groups, which, however, failed to reach statistical significance.

CONCLUSIONS

Both electrode types enable successful mfERG recordings. However, in compliant patients, the use of the DTL electrode appears preferable due to the larger amplitudes, higher signal-to-noise ratio and its better reflection of physiological changes, i.e., age effects. Nevertheless, skin electrodes appear a viable alternative for mfERG recordings in patients in whom the use of corneal electrodes is precluded, e.g., children and disabled patients.

Retinal and Visual Pathways Involvement in Carriers of Friedreich's Ataxia

Friedreich’s ataxia (FRDA) is a rare autosomal recessive neurodegenerative disorder due to the homozygous pathological expansion of guanine-adenine-adenine (GAA) triplet repeats in the first intron of the FXN gene, which encodes for the mitochondrial protein frataxin. In the visual system, the typical manifestations are ocular motility abnormality, optic neuropathy, and retinopathy. Despite the evidence of ophthalmological impairment in FRDA patients, there is a lack of information about the morpho-functional condition of the retina and of the optic pathways in healthy heterozygous carriers of Friedreich’s ataxia (C-FRDA). Ten C-FRDA subjects (providing 20 eyes) and thirty-five Controls (providing 70 eyes) underwent a complete neurological and ophthalmological examination comprehensive of functional (full-field Electroretinogram (ffERG), multifocal Electroretinogram (mfERG), Visual Evoked Potential (VEP), and Pattern Reversal Electroretinogram (PERG)) and morphological assessments (Optical Coherence Tomography, OCT) of the retina, macula, retinal ganglion cells, and visual pathways. The groups’ data were compared using a two-sample t-test. Pearson’s test was used to investigate the morpho-functional correlations. Statistically significant differences (p < 0.01) between C-FRDA and Control eyes for the values of the following parameters were found: ffERG b-wave amplitude, mfERG Response Amplitude Densities, PERG P50 implicit time and P50-N95 amplitude, VEP P100 implicit time, Retinal Nerve Fiber Layer (RNFL) Overall, and Nasal thickness. The values of the OCT macular volume were not statistically different (p > 0.01) between the two Groups. Therefore, our data suggest that, in C-FRDA, a dysfunction of retinal elements without morphological macular impairment may occur. In addition, a morphological impairment of RNFL associated with an abnormal neural conduction along the visual pathways can be also detected.

Electrophysiological and anatomical outcomes of subthreshold micropulse laser therapy in chronic central serous chorioretinopathy

BACKGROUND

To evaluate short-term efficacy of subthreshold micropulse laser therapy on chronic central serous chorioretinopathy (CSC) electrophysiologically and anatomically.

METHODS

This prospective study included 18 eyes with chronic CSC. Subthreshold micropulse laser therapy was applied to the eyes using Endpoint Management System (EpM). The efficacy of the treatment was evaluated with optical coherence tomography (OCT) and multifocal electroretinography (mfERG) measurements before and after one month of the treatment.

RESULTS

The mean patient age was 47.3 ± 5.7 years (ranged between 36 and 56). The mean symptomatic time of the disease was 12.7 ± 3.33 months. Central macular thickness, choroidal thickness, subretinal fluid height and width showed statistically significant decreases after EpM treatment (p < 0.05). P 1 amplitude of ring 1, 3, 4, and 5 in mfERG increased significantly (p <  0.05).

CONCLUSIONS

The study demonstrated that, in both OCT and electrophysiological evaluations, EpM subthreshold laser therapy resulted in anatomical and functional improvements in chronic CSC.

MERCI: a machine learning approach to identifying hydroxychloroquine retinopathy using mfERG

PURPOSE

Hydroxychloroquine (HCQ) is an anti-inflammatory drug in widespread use for the treatment of systemic auto-immune diseases. Vision loss caused by retinal toxicity is a significant risk associated with long term HCQ therapy. Identifying patients at risk of developing retinal toxicity can help prevent vision loss and improve the quality of life for patients. This paper presents updated reference thresholds and examines the diagnostic accuracy of a machine learning approach for identifying retinal toxicity using the multifocal Electroretinogram (mfERG).

METHODS

A retrospective study of patients referred for mfERG testing to detect HCQ retinopathy. A consecutive series of all patients referred to Kensington Vision and Research Centre between August 2017 and July 2020 were considered eligible. Eyes suspect for other ocular pathology including widespread retinal disease and advanced macular pathology unrelated to HCQ or with poor quality mfERG recordings were excluded. All patients received mfERG testing and Ocular Coherence Tomography (OCT) imaging. Presence of HCQ retinopathy was based on ring ratio analysis using clinical reference thresholds established at KVRC coupled with structural features observed on OCT, the clinical reference standard. A Support Vector Machine (SVM) using selected features of the mfERG was trained. Accuracy, sensitivity and specificity are reported.

RESULTS

1463 eyes of 748 patients were included in the study. SVM model performance was assessed on 293 eyes from 265 patients. 55 eyes from 54 patients were identified as demonstrating HCQ retinopathy based on the clinical reference standard, 50 eyes from 49 patients were identified by the SVM. Our SVM achieves an accuracy of 85.3% with a sensitivity of 90.9% and specificity of 84.0%.

CONCLUSIONS

Machine learning approaches can be applied to mfERG analysis to identify patients at risk of retinopathy caused by HCQ therapy.

Visual function during and after an acute central serous chorioretinopathy episode

PURPOSE

To evaluate visual function parameters during and after an acute central serous chorioretinopathy (CSC) episode.

METHODS

A prospective study included 19 fovea involving acute CSC patients with episode resolution within 3 months from the episode onset. Optical coherence tomography, best corrected visual acuity (BCVA), contrast sensitivity (CS), microperimetry (MP), and multifocal electroretinography (mfERG) were performed at baseline, 3 and 6 months from the episode onset. In a sub analysis, patients were divided into groups with greater (gMV, N = 9) and lower (lMV, N = 10) macular volume at presentation, and functional outcomes were observed.

RESULTS

BCVA (p < 0.001), average CS (CS-A) (p < 0.001), average retinal sensitivity (MP-A) (p < 0.001), mfERG amplitude densities in the first and second ring (mfERG-A1, p < 0.001; mfERG-A2, p = 0.017), and implicit times in the first, second, and third ring (mfERG-IT1, p = 0.024; mfERG-IT2, p = 0.002; mfERG-IT3, p = 0.018) improved with episode resolution 3 months after the episode onset. From 3 to 6 months after the episode onset, only CS-A (p = 0.045) continued to improve. Patients in the gMV group had lower mfERG-A1 (p = 0.017) and central retinal sensitivity (MP-C, p = 0.05) 6 months from the episode onset.

CONCLUSIONS

Although all functional parameters mostly improve with CSC episode resolution, only CS continues to improve thereafter. Patients with greater MV at presentation have worse functional outcomes. Visual function impairment in acute CSC patients is confined to the topographical area of subretinal fluid detachment.

The relation of the multifocal electroretinographic response to macular layer volume

PURPOSE

To determine the association of the multifocal electroretinographic (mfERG) response amplitude with the volumes of the inner, postreceptor, and photoreceptor retinal layers in the region stimulated by each mfERG element.

METHODS

Sixteen healthy, young adult control subjects were studied. Each of the 103 hexagonal elements of the standard, scaled mfERG were aligned, where possible, with patches of retina imaged using optical coherence tomography. Stimuli falling on the fovea and on the optic nerve head were excluded. Linear mixed-effects modeling was then used to derive estimated coefficients (voltage/volume) for the mfERG response throughout the full 80 ms standard epoch. The resulting predicted response amplitudes originating in each layer were then compared to pharmacologically "dissected" mfERGs obtained from other studies in monkey eyes.

RESULTS

Across the duration of the response, the amplitude of the modeled contribution from (1) the inner retina was small-to-modest, (2) the postreceptor retina was larger and contained two prominent peaks, and (3) the photoreceptor response was the largest and most closely paralleled the overall (i.e., intact) response, including late-appearing oscillations. The significance of each layer's contribution was greatest when the absolute amplitude of that layer's response was largest. The contribution of the inner retina was maximally significant in the interval between the prominent troughs and peaks of the intact response. The contributions of the postreceptor and photoreceptor responses were maximally significant at the prominent troughs and peaks of the intact response.

CONCLUSIONS

The results of the model were in good overall agreement with previous interpretations of the cellular contributions to the mfERG. There was also fair agreement with pharmacologically dissected monkey mfERG responses. Thus, the estimations of the contributions of the retinal layers to the mfERG so produced appeared plausible.

Macular vascular density and visual function after phacoemulsification in cataract patients with non-pathological high myopia: a prospective observational cohort study

PURPOSES

This study aimed to evaluate changes in macular vascular density and macular function in patients with high myopia cataract (HMC) after phacoemulsification surgery, using optical coherence tomography angiography (OCTA) and multifocal electroretinography (mfERG).

METHODS

Patients with cataracts scheduled for phacoemulsification surgery were divided into a high myopia group (axial length > 26.5 mm) and a control group (22 mm < axial length ≤ 24.5 mm). OCTA examinations were performed before surgery and at 1 day, 1 week, 1 month, and 3-6 months post-surgery, while mfERG was conducted before surgery and at 3-6 months post-surgery.

RESULTS

A total of 38 patients were included, of whom 20 were HMC patients and 18 were control patients. The macular vascular density significantly increased after phacoemulsification surgery in both groups, while foveal avascular zone area decreased significantly (HMC group: all p < 0.01; control group: all p < 0.05). Mean changes in macular vascular density were significantly greater in HMC patients than in the control group at 1 day after surgery (all p < 0.05). The amplitude density and latency of P1 wave in all macular rings (Ring_1-5) did not differ significantly before or after surgery in either group (all p > 0.1).

CONCLUSION

Phacoemulsification may not affect HMC patients' macular mfERG responses within 3-6 months post-surgery, but it may influence macular microcirculation. HMC patients should be closely monitored after surgery, as their retinal vascular density may fluctuate substantially in the early postoperative period.

Assessment of optical coherence tomography angiography and multifocal electroretinography in eyes with and without nonproliferative diabetic retinopathy

Purpose:

To examine (i) the retinal structure and function using optical coherence tomography angiography (OCTA) and multifocal electroretinography (mfERG), respectively, in eyes with and without nonproliferative diabetic retinopathy (NPDR), (ii) and their interrelationship between retinal structure (OCTA) and function (mfERG) in the two groups independently.

Methods:

This was a prospective observational study. One hundred twenty-one eligible participants with type 2 diabetes with No DR (n = 89), or with mild or moderate NPDR (n = 32) underwent ophthalmic examination, ultrawide field-view fundus photography, OCTA, and mfERG. Group differences were assessed using a Mann–Whitney U test. Correlations were assessed using Spearman's rho.

Results:

There were no significant differences in OCTA measures between the two groups. The mfERG P1 implicit times (rings 1–6) were significantly delayed and P1 response densities in rings 5 and 6 were significantly lower in participants with NPDR compared to those with No DR. In those with No DR, P1 implicit times in almost all rings were delayed in relation to lower vessel density and perfusion (maximum variance noted was 13%). In individuals with NPDR, the P1 response density in rings 2 and 3 showed a positive nonsignificant correlation with macular perfusion.

Conclusion:

In those with diabetes with No DR, retinal neuronal function is influenced by lower macular vessel density and perfusion. The retinal neuronal function is abnormal in individuals with NPDR compared to those with No DR and is not correlated with OCT angiometric measures, suggesting the likelihood of a different retinal structural correlate.

Functional retinal outcomes in patients with prediabetes and type 2 diabetes

PURPOSE

Type 2 diabetes (T2DM) is a leading cause of visual impairment. Its precursor, prediabetes (preDM), is growing in numbers every year. While it is well known that T2DM causes changes in retinal function early in the disease process, it is likely that some of these changes emerge during the preDM stage. This study evaluates retinal function measures in patients with preDM to determine if there are differences in colour vision, contrast sensitivity (CS), and multifocal electroretinogram (mfERG) measures present before T2DM is diagnosed.

METHODS

The L'Anthony desaturated D-15 test, Mars Chart CS test, and mfERG were administered on the right eye of 43 participants; 15 controls (HbA1c ≤ 5.6%), 17 with preDM (HbA1c 5.7%-6.4%), and 11 with T2DM (either physician diagnosed or with untreated HbA1c ≥ 6.5%). HbA1c values were measured at the time of the other tests. Colour vision confusion scores (CVCS) were calculated from the D-15 using the method developed by Torok. Multivariate regression (which controlled for age differences) was used to evaluate the relationship of HbA1c and functional measures. Kruskal-Wallis tests were also used to evaluate differences between groups with post-hoc analysis.

RESULTS

CVCSs were significantly different between the three groups (p = 0.009). There was an association between higher CVCS and higher HbA1c values across all groups as well as specifically within the preDM group when controlling for age (R²  = 0.29, p = 0.01 and R²  = 0.39, p = 0.02 respectively). Multivariate regression of all of the functional tests together and HbA1c found only colour vision remained significant, indicating that the functional examination metrics may provide redundant data, with similar changes in prediabetes where colour vision may be the strongest indicator early in the process.

CONCLUSIONS

Patients with prediabetes have functional changes that can be measured in the retina before the diagnosis of diabetes, with the L'Anthony D-15 colour vision test providing the strongest association with glucose dysregulation in this population. This has important implications for follow up and screening for diabetes within optometric practices. Further studies are needed to follow these patients over time to see how and when these metrics change.

Dexamethasone Intravitreal Implant (Ozurdex) in Paediatric Patients with Non-infectious Intermediate Uveitis and Related Cystoid Macular Oedema: Evaluation of Macular Morphology and Function with Six-month Follow-up; a Deeper Role of MfERG?

PURPOSE

To evaluate the efficacy of Ozurdex implant by analyzing macular morphology and function in pediatric uveitis and related cystoid macular edema (CMO).

METHODS

Main outcomes were visual acuity, mfERG and photopic ERG response, and central macular thickness. Mean values recorded at each time-point were compared to baseline and correlations between functional and anatomical parameters were evaluated.

RESULTS

Resolution of intraocular inflammation and CMO was achieved in all eyes 1 month after implant without procedure or drug-related complications. Mean visual acuity and mfERG amplitude improved showing a statistically significant difference to baseline values for the first 4 months. Mean central macular thickness showed a statistically significant reduction for all follow-up time. Photopic ERG did not vary significantly. Statistically significant correlation was found between trends of visual acuity, central macular thickness, and mfERG responses.

CONCLUSION

Correlation found between macular morphology and function confirms the efficacy of Ozurdex in pediatric uveitis.

Role of multifocal electroretinogram in assessment of early retinal dysfunction in hypertensive patients

PURPOSE

To investigate localized retinal dysfunction in hypertensive patients using multifocal electroretinogram (mfERG) and to assess its sensitivity as an early predictor for the development of retinopathy in hypertensive patients.

METHODS

Ninety-eight eyes were included in this case-control study. Twenty-eight eyes of healthy subjects served as a control group (group I). Seventy eyes belonged to patients with systemic hypertension assigned into two groups; group II including 39 eyes of hypertensive patients with normal fundus and group III including 31 eyes of patients with signs of hypertensive retinopathy. All participants were subjected to complete ophthalmic and electrophysiological examination using mfERG. N1 and P1 wave amplitudes and implicit times from the central hexagon and four concentric rings across the visual field were analyzed.

RESULTS

mfERG amplitudes were significantly reduced in hypertensive group with retinopathy than in controls. N1 amplitude was significantly reduced in the most eccentric ring in eyes of hypertensive patients with normal fundus.

CONCLUSION

mfERG is a sensitive objective tool for assessment of retinal dysfunction in hypertensive patients. mfERG amplitude is a promising predictor for early development of retinopathy in systemic hypertension.

Detection of structural and electrical disturbances in macula and optic nerve in Alzheimer's patients and their correlation with disease severity

Aim: To evaluate and compare structural and functional changes in macula and optic nerve in Alzheimer disease (AD) patients and healthy subjects.Methods: Both eyes of 20 AD patients and 40 age-matched healthy controls were evaluated. All subjects were evaluated by cognitive testing and comprehensive ophthalmological examination, including visual acuity, visual fields, color vision, contrast sensitivity, anterior, and posterior segment examination, optical coherence tomography, multifocal electroretinography (mfERG), and pattern-reversal visual evoked potential (pVEP).Results: AD patients showed significantly reduced contrast sensitivity, thinner nerve fiber layer, ganglion cell layer andmacular volume. Multifocal ERG wave amplitudes were significantly reduced with delayed implicit times, which correlated significantly with the inner retinal layer thinning and poorer disease severity scores. The correlation with structural changes and disease severity was highest for pVEP, which showed significant derangement in AD patients.Conclusion: Subclinical visual dysfunction may be present in AD patients, which may be detected as inner retinal thinning. A probable photoreceptor abnormality may also form a part of the AD disease process.

Surgery for Idiopathic Epimacular Membrane: Morpho-Functional Outcomes Based on the Preoperative Macular Integrity of the Photoreceptoral Junction. A Prospective Pilot Study

INTRODUCTION

This study aimed to evaluate whether the preoperative integrity of the inner segment (IS) and outer segment (OS) photoreceptoral junction may influence the postoperative visual acuity, the macular morphology [assessed by spectral domain optical coherence tomography (SD-OCT)], and macular function (evaluated by multifocal electroretinogram, mfERG) in patients with idiopathic epimacular membrane (EMM) followed up for 6 months.

METHODS

In this observational prospective study, 18 patients with EMM (mean age 72.5 ± 6.87 years) were enrolled. They were divided into two groups according to the preoperative integrity of the SD-OCT IS/OS junction: the EMM-I group with an intact IS/OS junction (11 patients, mean age 72.75 ± 3.49 years, providing 11 eyes) and the EMM-D group with a disrupted IS/OS junction (7 patients, mean age 70.86 ± 10.79 years, providing 7 eyes). For each enrolled patient, visual acuity (VA), mfERG, and SD-OCT were assessed at baseline (preoperative) and after 1, 3, and 6 months of follow-up after surgical treatment for EMM (pars plana vitrectomy with EMM removal and internal limiting membrane peeling).

RESULTS

During the whole follow-up, VA was significantly increased in EMM-I eyes and unmodified in EMM-D eyes. In both groups, mfERG responses were not significantly different and not related to VA differences. In EMM-I eyes a significant reduction of central retinal thickness (CRT) was observed; however, it was not correlated with VA changes. In EMM-D eyes CTR was not significantly reduced, whereas macular volume was significantly reduced. These changes were significantly related to the corresponding differences in VA.

CONCLUSIONS

Our results suggest that the preoperative evaluation of the integrity of the IS/OS junction is relevant for postoperative outcomes. The recovery in VA was higher in EMM-I eyes than in EMM-D eyes. Postoperative recovery was not associated with morphology of the outer retina (photoreceptor and outer nuclear layer) and the function of preganglionic elements.

Effects of Macuprev® Supplementation in Age-Related Macular Degeneration: A Double-Blind Randomized Morpho-Functional Study Along 6 Months of Follow-Up

Background

To evaluate the effects of Macuprev^® supplementation on macular function and structure in intermediate age-related macular degeneration (AMD) along 6 months of follow-up.

Methods

In this double-blind, monocentric, randomized, and prospective study, 30 patients with intermediate AMD were enrolled and randomly divided into two age-similar groups: 15 patients (AMD-M group; mean age 68.50 ± 8.79 years) received 6-month oral daily supplementation with Macuprev^® (Farmaplus Italia s.r.l., Italy, two tablets/day on an empty stomach, before meals; contained in total lutein 20 mg, zeaxanthin 4 mg, N-acetylcysteine 140 mg, bromelain 2500GDU 80 mg, vitamin D₃ 800 IU, vitamin B₁₂ 18 mg, alpha-lipoic acid 140 mg, rutin 157 mg, vitamin C 160 mg, zinc oxide 16 mg, Vaccinium myrtillus 36% anthocyanosides 90 mg, Ganoderma lucidum 600 mg) and 15 patients (AMD-P group; mean age 70.14 ± 9.87) received two tablets of placebo daily on an empty stomach, before meals. A total of 28 eyes, 14 from each AMD group, completed the study. Multifocal electroretinogram (mfERG) and spectral domain-optical coherence tomography (SD-OCT) were assessed at baseline and after 6 months.

Results

At 6-month follow-up, AMD-M eyes showed a significant increase of mfERG response amplitude density (RAD) recorded from the central macular areas (ring 1, 0–2.5°; ring 2, 2.5–5°), whereas non-significant changes of retinal and choroidal SD-OCT parameters were found when values were compared to baseline. Non-significant correlations between functional and structural changes were found. In AMD-P eyes, non-significant differences for each mfERG and SD-OCT parameters were observed at 6 months.

Conclusions

In intermediate AMD, Macuprev^® supplementation increases the function of the macular pre-ganglionic elements, with no associated retinal and choroidal ultra-structural changes.

Trial Registration

ClinicalTrials.gov identifier, NCT03919019.

Funding

Research for this study was financially supported by the Italian Ministry of Health and Fondazione Roma. Article processing charges were funded by Farmaplus Italia s.r.l., Italy.

Revealing a retinal facilitatory effect with the multifocal ERG

PURPOSE

We have previously shown that the amplitude of the mfERG response obtained to a single (large) hexagon is significantly smaller than that obtained when summating all the mfERG responses evoked to an array of 7-61 hexagons covering the same retinal area. The purpose of this study was to confirm our initial findings in normal subjects of different ages and in selected patients.

METHODS

Binocular mfERGs (1, 7, 19, 37 and 61 hexagon arrays; Espion V6.0.54 Diagnosys LLC) were recorded from 40 normal subjects (25 aged 18-25, and 15 aged 3-12). Individual mfERG waveforms evoked in response to the multi-hexagon arrays (7, 19, 37 and 61) were summated, and the amplitude of the resulting composite mfERG waveform was compared to that measured in the response evoked to the single (large) hexagon stimulus to yield the amplitude ratio (i.e., 7:1 X100, 19:1X100, etc.).

RESULTS

In normal subjects, the 7:1 ratio was 119.5 ± 9.2%, a value that gradually decreased to reach 109.4 ± 20.6% with the 61:1 ratio and a finding that was similar across all ages.

CONCLUSION

The present study indicates a significant enhancement in amplitude of the summed mfERG composite waveform evoked to the 7 hexagon stimulus array (and to a lesser extent to the 19, 37 and 61 stimuli) compared to the 1 hexagon array, possibly mediated through the retinal lateral pathway (horizontal or amacrine cells), a claim that awaits confirmation. Preliminary results obtained from patients treated with Plaquenil suggest that this new method of mfERG analysis might probe a feature of macular function different from that investigated with the more usual method of mfERG ring ratio.

Foveal amplitudes of multifocal electroretinograms are larger following full-field electroretinograms

PURPOSE

The clinical standards for multifocal electroretinograms (mfERG) call for adaption to normal room lighting before the mfERG begins. They specify that any assessments where bright lights are used, should be done after the mfERG to prevent excess stimulation of retinal cells. However, full-field electroretinograms (FFERG) are performed prior to mfERGs in some clinical settings. It is unclear from the literature whether the FFERG has an impact on the mfERG. This study seeks to examine the effect of the FFERG on the mfERG when performed sequentially.

METHODS

Thirty young healthy subjects (age 27.1 ± 3.5 years) were included. Patients reported for two visits and were fully dilated at both visits. At visit one, a FFERG was recorded (VERIS 6.2) using our clinical protocol which includes an ISCEV standard flash sequence; each flash condition was repeated 4-6 times. Following the FFERG, an mfERG was recorded using a 4-min m-sequence at near 100% contrast. At visit two, only the mfERG was recorded. A Burian-Allen contact lens electrode filled with celluvisc was used for all recordings. The two mfERGs were compared for foveal, peripheral, and overall implicit time (IT) and amplitudes (amp). Paired t tests were used to evaluate the data. Coefficient of variation and Bland-Altman analysis was also reported for this patient group.

RESULTS

There was a small but statistically significant difference in foveal amplitudes (amp) (p = 0.004) wherein the amp was larger following the FFERG stimuli. The mean difference was 11.1 nV/deg² (100.9 nV vs 89.8 nV). There was no difference in foveal IT (p = 0.66). There was no difference in overall IT or amp when averaging the entire eye (p = 0.44 amp and p = 0.54 IT) or just evaluating the periphery (p = 0.87 amp and p = 0.051 IT). Bland-Altman analysis found a coefficient of repeatability overall was 1.57 ms (IT) and 10.7 nV/deg² (amp).

CONCLUSIONS

The difference in foveal amplitude is likely the result of a small long-term cone adaptation, but further studies are needed. While it is statistically significant, the small difference is unlikely to be clinically important. These results should help increase clinical confidence in mfERG results when recorded following a FFERG.

Electrophysiological and clinical tests in dry age-related macular degeneration follow-up: differences between mfERG and OCT

BACKGROUND

Age-related macular degeneration (AMD) is one of the major causes of progressive and debilitating visual impairment in developed countries and has become a growing health and social issue that needs to be addressed. Imaging techniques and functional tests are useful to assess the degree of macular dysfunction and AMD progression. However, given the slow progression of the disease, it is necessary to identify which techniques are more sensitive for the diagnosis and monitoring of patients with AMD.

PURPOSE

To study changes observed with both imaging techniques and electrophysiological tests in dry AMD-diagnosed patients during 2 years in order to identify the most sensitive technique.

METHODS

Fundus photography, OCT (macular thickness and number of drusen), Pattern VEP (P100 wave), Pattern ERG (P50 wave) and multifocal ERG (central rings) were carried out in 30 patients that were diagnosed with dry AMD in both eyes. The tests were repeated 1 and 2 years later.

RESULTS

No statistically significant changes were observed in visual acuity or in the severity of the disease throughout the study. OCT showed an increase in the number of drusen, as well as in macular thickness. As for the electrophysiological techniques, no significant changes were observed throughout the study in Pattern VEP or Pattern ERG. mfERG showed significant alterations. Statistical analysis showed that mfERG is more efficient in detecting changes throughout the experimental period.

CONCLUSIONS

OCT and mfERG are useful in the diagnosis and monitoring of dry AMD patients, whilst mfERG is the most sensitive technique to study the progression of this disease in short periods of time.

Intrafamilial heterogeneity of congenital optic disc pit maculopathy

BACKGROUND

Optic disc pit is a very rare clinical entity. The main complication of this condition is the maculopathy. Report of cases: A 40-year-old Caucasian man and his 6-year-old daughter underwent a complete ophthalmological examination. In both cases ophthalmoscopy examination showed a bilateral white-yellow oval depression in the optic disc. Optical coherence tomography showed maculopathy with different degrees of severity in the two cases. Microperimetry and multifocal-electroretinography showed different degrees of retinal dysfunction in both cases. Molecular genetic analysis was performed and the possible pathogenic role of the MIR204 gene was excluded.

DISCUSSION

The findings of our familial cases support the hypothesis that optic disc pit associated with maculopathy could be a genetic disease with an autosomal dominant inheritance pattern. Optical coherence tomography is the most helpful diagnostic tool to assess maculopathy associated with optic disc pit. Microperimetry and multifocal-electroretinography are useful for the diagnosis of macular dysfunction in the early stages, and for the prognosis and follow-up of optic disc pit-maculopathy which is the main cause of visual impairment in these patients. Furthermore, in consideration of the variable expressivity and disease severity reported in our cases, genetic anticipation may be hypothesized.

The macular function and structure in patients with diabetic macular edema before and after ranibizumab treatment

Purpose

To evaluate macular function and structure in patients with diabetic macular edema prior to, as well as 3 and 6 months after intravitreal ranibizumab treatment.

Patients and methods

Seventeen eyes of 17 patients with type 2 diabetes mellitus and diabetic macular edema (DME) were treated with intravitreal injections of 0.5 mg ranibizumab. Prior to the first injection, as well as after 3 and 6 months, the following examinations were performed: assessment of distance best-corrected visual acuity (log MAR), perception of metamorphopsia (M-Chart), slit lamp examination of the anterior and posterior segment of the eye (Volk 90D lens), evaluation of the retinal and choroidal circulation (fluorescein angiography), assessment of the structure and thickness of the macula (OCT), as well as evaluation of the macular function (PERG and mfERG).

Results

We observed that ranibizumab significantly improved visual acuity after 3 and 6 months from the beginning of the treatment, which was a consequence of reduced macular edema and vascular leakage. There was a statistically significant decrease in metamorphopsia frequency at month 3; however, at month 6 it was a statistically insignificant when compared to the baseline. The results of electrophysiological examinations revealed no improvement in ranibizumab-treated patients.

Conclusion

Improvement of visual acuity and reduction in macular thickness were maintained up to the 6-month follow-up. The results of electrophysiological examinations revealed that ranibizumab injections tend to stabilize bioelectrical macular function of the outer, middle and inner retinal layers, which was impossible to recognize on the basis of visual acuity and OCT. Therefore, the electrophysiological examinations should be used as an additional objective tool for the evaluation of the anti-VEGF treatment effectiveness in DME.

Treatment of vitamin A deficiency retinopathy with sublingual vitamin A palmitate

PURPOSE

To report treatment of vitamin A deficiency retinopathy with sublingual vitamin A drops.

METHODS

Case report with review of the literature.

RESULTS

A 69-year-old Caucasian woman with a history of small bowel resection presented with progressive symptoms of bilateral nyctalopia and decreased visual acuity. Ophthalmic examination revealed bilateral conjunctival xerosis and fine white granular deposits in the midperipheral retina suggestive of vitamin A deficiency. Full-field electroretinogram (ERG), multifocal ERG (mfERG), and two-color dark adaptometry revealed significant impairment of rod and cone photoreceptor function. Kinetic perimetry demonstrated depressed macular sensitivity with constriction of the finer isopters. After 5 months of treatment with sublingual vitamin A drops, the patient's vision, ERG, mfERG, dark adaptometry, and perimetry normalized. A review of the literature summarizing the electrophysiologic testing in vitamin A deficiency is also discussed.

CONCLUSIONS

This case highlights novel observations on the effects of sublingual vitamin A supplementation for acquired vitamin A deficiency retinopathy. Sublingual vitamin A may represent a viable and efficacious treatment modality for vitamin A deficiency.

The assessment of multifocal ERG responses in school-age children with history of prematurity

PURPOSE

The authors examined macular function in preterm-born children, using multifocal ERG (mfERG). Possible alterations in P1 amplitudes, P1 amplitudes density and P1 implicit time between school-age children with history of prematurity and their peers were researched. The correlations between parameters of mfERG responses and birth weight, gestational age, macular volume and central macular thickness were verified.

METHODS

A group of 18 preterm-born school-age children were analyzed (mean age 10.18 ± 1.21 years). The study group was compared to the group of 15 peers born appropriate for gestational age (mean age 10.8 ± 1.52 years). The mfERG was evaluated in all children.

RESULTS

There were statistically significant differences for P1 amplitudes from ring 1 (p = 0.0001) and P1 amplitudes density from ring 1 (p = 0.0001). Calculating the correlation coefficients, we receive significant results for P1 amplitudes from ring 1 versus gestational age (r = 0.54; p = 0.026), birth weight (r = 0.54; p = 0.026) and central macular thickness (r = -0.62; p = 0.008), and for P1 amplitudes density from ring 1 versus central macular thickness (r = -0.51; p = 0.034).

CONCLUSIONS

The study suggests that P1 amplitudes and P1 amplitudes density vary in preterm-born children in comparison with their peers born appropriate for gestational age, which might suggest discreet macular dysfunction. The correlation between low birth weight, early gestational age, central macular thickness and mFERG components from ring 1 might evidence that decreased bipolar cells density caused by premature birth is the result of altered development of central retina reflecting in structural anomalies of the fovea.

The effects of fundus photography on the multifocal electroretinogram

PURPOSE

To determine the effect of flash fundus photography (FFP) on the multifocal electroretinogram (mfERG).

METHODS

Ten subjects underwent mfERG testing on three separate dates. Subjects received either mfERG without FFP, mfERG at 5 and 15 min after FFP, or mfERG at 30 and 45 min after FFP on each date. The FFP groups received 10 fundus photographs followed by mfERG testing, first of the right eye then of the left eye 10 min later. Data were averaged and analyzed in six concentric rings at each time point. Average amplitude and implicit times of the N1, P1, and N2 peaks for each concentric ring at each time point after FFP were compared to baseline.

RESULTS

Flash fundus photography did not lead to a significant change of amplitude or implicit times of N1, P1, or N2 at 5 min after light exposure.

CONCLUSIONS

These findings suggest that it is acceptable to perform mfERG testing without delay after performance of FFP.

Peripapillary retinal vessel diameter correlates with mfERG alterations in retinitis pigmentosa

PURPOSE

To investigate relationship between the peripapillary retinal vessel diameter and the residual retinal function, measured by mfERG, in patients with retinitis pigmentosa (RP).

PATIENTS AND METHODS

A cross-sectional study based on 23 patients with RP (43 eyes) and 20 controls (40 eyes) was performed. Retinal vessel diameters were measured using a computer-based program of the retinal vessel analyser (RVA; IMEDOS Systems UG, Jena, Germany). We evaluated the mean diameter in all four major retinal arterioles (D-A) and venules (D-V) within 1.0-1.5 optic disc diameters from the disc margin. The data were compared with the N1 amplitudes (measured from the baseline to the trough of the first negative wave), with the N1P1 amplitudes (measured from the trough of the first negative wave to the peak of the first positive wave) of the mfERG overall response and with the mfERG responses averaged in zones [zone 1 (0°-3°), zone 2 (3°-8°), zone 3 (8°-15°) and zone 4 (15°-24°)].

RESULTS

Mean (±SD) D-A and D-V were narrower in patients with RP [84.86 μm (±13.37 μm) and 103.35 μm (±13.65 μm), respectively] when compared to controls [92.81 μm (±11.49 μm) and 117.67 μm (±11.93 μm), respectively; the p-values between groups were p = 0.003 for D-A and p < 0.001 for D-V, linear mixed-effects model]. The RP group revealed clear differences compared to the controls: D-A and D-V became narrower with reduced mfERG responses. D-V correlated significantly with the overall mfERG N1 amplitudes (p = 0.013) and with N1P1 amplitudes (p = 0.016). D-V correlated with the mfERG amplitudes averaged in zones: (zone 2, 3 and 4; p ≤ 0.040) and N1P1 mfERG amplitudes (zones 1, 2, 3 and 4; p ≤ 0.013).

CONCLUSIONS

Peripapillary retinal vessel diameter is reduced in RP proportionally to functional alterations.

A case of Mac Tel 2 with an unusual sub macular vitelliform lesion

Method: Observational case report describing the clinical, FFA, OCT and mfERG findings in an elderly female patient with atypical features of macular telangiectasia (Mac Tel 2)

Results: A 71-year-old lady was detected to have characteristic features of Mac Tel 2 in the left eye (LE) and a yellowish sub macular vitelliform like lesion in the right eye (RE). FFA showed ill defined hyper fluorescence in the RE and telangiectasia and parafoveal leakage typical of Mac Tel 2 in the LE. On OCT RE had hyper reflective clump of echoes subfoveally with an intact RPE and LE had foveal thinning with hypo reflective intraretinal cavities. mfERG responses were normal in the RE and reduced in the LE. During the course of 3 years LE showed natural progression while RE remained unchanged.

Conclusion: Structural and functional evaluation of an unusual sub macular vitelliform lesion seen in association with Mac Tel 2 and its course over a period of 3 years is described. The differentiating features of this lesion from adult onset foveomacular vitelliform dystrophy (AFMD) are discussed.

Electrophysiological examination in uveitis: a review of the literature

Purpose

Uveitis is the inflammation of the uveal tract, which usually also affects the retina and vitreous humor. The electrophysiological examination is an objective ocular examination that includes the electroretinogram, visual evoked potentials, the electrooculogram, the multifocal electroretinogram, and multifocal visual evoked potentials. Our aim is to review the literature of the use of the electrophysiological examination in cases of uveitis.

Methods

We performed a systematic search of the literature of published papers until October 2012 using the PubMed search engine. The key terms that were used were “uveitis”, “electrophysiological examination”, “electroretinogram”, “visual evoked potentials”, “electrooculogram”, “multifocal electroretinogram”, and “multifocal visual evoked potentials” in multiple combinations. To the best of our knowledge, this is the first review concerning the assessment of electrophysiology in uveitis.

Results

Our search of the literature demonstrated that the electrophysiological examination, mainly by means of electroretinogram, multifocal electroretinogram, and visual evoked potentials, is performed in several cases of uveitis for many purposes, including diagnosis and monitoring of disease progression and treatment efficacy. The electrophysiological examination is more useful in patients with multiple evanescent white dot syndrome, acute posterior multifocal placoid pigment epitheliopathy, birdshot chorioretinopathy, Vogt–Koyanagi–Harada disease, Adamantiades–Behçet disease, ocular syphilis, and Fuchs heterochromic cyclitis.

Conclusion

This review summarizes the use of the electrophysiological examination in uveitic patients and underlines its value as a useful tool in the objective assessment and the monitoring of the disease.

Correlation between optical coherence tomography and multifocal electroretinogram findings with visual acuity in retinitis pigmentosa

Introduction

Our purpose was to study the correlation between the macular morphology and function in eyes with retinitis pigmentosa (RP).

Methods

Sixty-six eyes from 33 patients with RP and with different visual acuity (VA) were studied using optical coherence tomography (OCT) and multifocal electroretinogram (mfERG). Correlation analysis was performed between VA, macular thickness, mfERG amplitude, and latency.

Results

Retinal thickness, retinal response density, and latency of the mfERG in the foveal area were independently and positively associated with VA (P = 0.002; P < 0.0001; P = 0.029; and P = 0.002, respectively), whereas there was no evidence for a correlation between VA and the amplitude of mfERG in the parafoveal area. Evidence of a correlation between the OCT and the mfERG evaluation was of borderline significance (P = 0.047). Also, there was evidence for an inverse association of VA with latency in ring 1 and ring 2 (b = −0.138; 95% confidence interval: −0.261, −0.015; P = 0.029). In accordance with the univariate findings, when foveal retinal thickness, mfERG amplitude, and latency in ring 1 were inserted simultaneously in the same model, all the three variables remained significantly associated with VA (P = 0.016; P < 0.0001; and P = 0.031, respectively). Nevertheless, some individual values deviated from the expected range. More specifically, 15 eyes showed a normal retinal thickness, whereas the respective VA was relatively low and the mfERG values were abnormal. Conversely, in seven eyes, despite the low retinal thickness, the respective VA was high.

Conclusion

The combined use of OCT with mfERG appears to be more appropriate for the estimation of macular function.

Electroretinographic findings in transplant chorioretinopathy

Aim:

Transplant chorioretinopathy is a rare complication following solid organ or bone marrow transplantation and can result in severe vision loss. This series presents electroretinogram (ERG) results in patients with this condition.

Methods:

Patients who presented with bilateral vision loss following bone marrow or solid organ transplantation were identified. A complete ophthalmologic examination, fundus photography, and fluorescein angiography (FA) were performed. Full-field ERG was obtained in all patients and a multifocal ERG (mfERG) was obtained in two patients.

Results:

Four patients were identified. All patients had bilateral vision loss and displayed a characteristic pattern of mottled hyperfluorescence on FA. Three patients developed progressive vision loss ranging from 20/60 to hand motions whereas one retained 20/40 vision. All patients exhibited moderate to severe cone dysfunction, while the degree of rod abnormalities was varied. Two patients with severe cone dysfunction showed mild clinical changes initially, but later developed progressive vision loss and chorioretinal atrophy.

Conclusion:

Transplant chorioretinopathy patients undergoing ERG testing show cone dysfunction with a variable degree of rod dysfunction. ERG abnormalities preceded the visual acuity and clinical changes in two patients, suggesting that ERG may be a helpful predictor of the clinical course in this rare disease.