Implicit Times Research Articles

Synthesis, Properties, and Biocompatibility of 4-Carboxyphenyboronic Acid-Modified Gelatin-Methacryloyl: A Hydrogel for Retinal Surgeries.

The current surgical adjunctive for vitreoretinal surgeries fails to provide an adequate 3D structure for cellular regeneration. A one-pot synthesis of gelatin-methacryloyl (GelMA) followed by modification with 4-carboxyphenylboronic acid (4-CPBA) was performed to fabricate 4-CPBA-modified GelMA (4CPBA@GelMA), a gelatin-based hydrogel. 4CPBA@GelMA was photo-cross-linked by 405 nm violet light and examined using nuclear magnetic resonance (NMR), Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), and rheometry. In vitro biocompatibility was examined by Müller cell proliferation assays exposed to 4CPBA@GelMA and violet light. In vivo retinal biocompatibility was evaluated by electroretinography of rat eyes that were exposed to intravitreally injected and photo-cross-linked 4CPBA@GelMA at days 3, 7, 14, and 28 post-injection. Following electroretinography, histology and immunohistochemistry were performed on the retinas. The NMR results indicated amidation of GelMA by 4-CPBA, and FTIR confirmed the presence of the CPBA ring in 4CPBA@GelMA samples. SEM revealed that 4CPBA@GelMA had significantly larger pores than GelMA (56.9 ± 9.5 vs 35.1 ± 2.8 μm; P < 0.001). Rheological findings showed that, unlike GelMA and gelatin, 4CPBA@GelMA has Newtonian fluid properties at room temperature. Exposure to 4CPBA@GelMA did not significantly affect Müller cell viability in a proliferation assay; moreover, electroretinography findings indicated normal waveforms and implicit times, and histology and immunohistochemistry examinations revealed no significant changes. In this study, we established the high retinal compatibility of 4CPBA@GelMA. The low viscosity of 4CPBA@GelMA is ideal for injection via small-gauge needles, and the larger pore size and three-dimensional network both potentiate cellular migration and growth. These features made 4CPBA@GelMA a candidate for vitreoretinal surgical adjunctive that might promote retinal regeneration.

Housing RCS rats under specific pathogen-free conditions mildly ameliorates retinal degeneration and alters intestine microbiota

Retinitis pigmentosa (RP) is a genetic blinding disease with over 80 causative genes. Disease progression varies between patients with similar genetic backgrounds. We assessed the association between environment, gut microbiota, and retinal degeneration in the RP rat model Royal College of Surgeons (RCS). The rats were born and raised for two generations under specific pathogen-free (SPF, n = 69) or non-SPF conditions (n = 48). At the age of four weeks, SPF rats had significantly shorter dark-adapted a-wave and dark and light-adapted b-wave implicit times by electroretinogram (p = 0.014, p = 9.5*10−6, p = 0.009, respectively). The SPF rats had significantly less photoreceptor apoptosis at ages four, eight, and twelve weeks (all p < 0.022), significantly thicker debris zone at age 14 weeks, and smaller hypofluorescent lesions in SPF rats at ages 10–16 weeks, especially in the inferior retina. The non-SPF rats had significantly higher microbiota alpha diversity (p = 0.037) and failed to present the age-related maturation of Proteobacteria, Spirochaetes, Actinobacteria, and Bacteroidetes seen in SPF conditions. Specific microbial amplicon sequence variants were reduced in rats with more severe retinal degeneration. Our data suggest an environmental effect on retinal deterioration in RCS rats. These findings may lead to the development of novel microbiome-related interventions for retinal degeneration.

Age-dependencies of the electroretinogram in healthy subjects.

The purpose of this study was to evaluate the age-dependency of amplitudes and implicit times in the electroretinograms (ERGs) of healthy individuals and provide clinicians and researchers with a reference for a variety of stimulus paradigms. Full-field electroretinography was conducted on 73 healthy participants aged 14-73 using an extended ISCEV standard protocol that included an additional 9Hz flicker stimulus for assessing rod function and special paradigms for isolated On-Off and S-cone responses. Correlation coefficients and best-fit regression models for each parameter's age-dependency were calculated. Dark-adapted ERGs, in particular, displayed notable age-related alterations. The attenuation and delay of the b-wave with higher age were most significant in the dark-adapted, rod-driven 0.001cds/m2 flash ERG. The age-dependent reduction of the a-wave amplitude was strongest in the standard dark-adapted 3cds/m2 flash condition. Cone-driven, light-adapted responses to either flash or flicker stimuli displayed comparatively small alterations at higher age. S-cone function tended to diminish at an early age, but the effect was not significant in the whole population. The results suggest that rod and cone function decline at different rates with age, with rods being generally more affected by aging. Nonetheless, response amplitudes displayed a wide variability across the whole sample.

Partial rescue of the full-field electroretinogram in patients with RPE65-related retinal dystrophy following gene augmentation therapy with voretigene neparvovec-rzyl.

To present a series of patients with RPE65-related retinal dystrophy showing a partial rescue of the full-field electroretinogram (ERG) following gene replacement therapy with voretigene neparovec-rzyl (Luxturna®). This retrospective chart review examined 17 patients treated with voretigene neparovec-rzyl (VN) at the Casey Eye Institute (2018-2022). The last pre-operative ERG and all available post-operative ERGs were analyzed to identify subjects with functional rescue. Measurements of amplitudes and implicit times were compared to data from age-matched controls and the attenuation relative to the lower limit of normal (LLN) was calculated. For comparison with other functional exams, the last pre-operative and all post-treatment best-corrected visual acuity (BCVA) data, visual field (VF) tests and full-field threshold stimulus tests (FST) were also described. Of patients who underwent ERGs, most had unrecordable ERGs that did not change after treatment. However, we identified three patients, treated bilaterally, who demonstrated partial rescue of the full-field ERG in both eyes which was sustained during the course of the study. This is the largest series of patients treated with VN showing a partial rescue of the ERG. This is also the first report of bilateral ERG rescue, as well as the first description of ERG recovery occurring in non-pediatric subjects. Full-field ERG could be used in combination with other psychophysical tests and imaging modalities to detect and deepen our understanding of the response to this gene therapy approach.

Electroretinograms Recorded with Skin Electrodes from Post-Vitrectomy Silicone Oil Filled Eyes with Proliferative Diabetic Retinopathy.

To determine the physiological status of the retina by electroretinography (ERG) using skin electrodes and the RETevalTM system in eyes that had undergone pars plana vitrectomy (PPV) with silicone oil (SO) tamponade. The vitrectomy was performed for a retinal detachment and proliferative diabetic retinopathy (PDR). Retrospective case series. ERGs were recorded with the RETevalTM system (LKC Technologies Inc. Gaithersburg, MD; Welch Allyn, Inc. Skaneateles Falls, NY) from eight eyes with PDR before and after the SO removal. The amplitudes and implicit times of the a- and b-waves of the ERGs before the SO removal were compared to that after the SO removal. ERGs were recordable in four eyes before and after the SO removal and the a- and b-amplitudes improved in three eyes and worsened in one eye after the SO removal. In the remaining four eyes, ERGs were non-recordable both before and after the SO removal. These results indicate that ERGs picked up by skin electrodes can be used to assess the physiology of the retina in eyes with a SO tamponade. The flat ERGs in the SO-filled eye indicated the presence of diffuse retinal damage which was confirmed by the flat ERGs after the SO removal.

Effects of angle of incidence of stimulus light on photopic electroretinograms of zebrafish larvae

In electroretinographic (ERG) recordings of zebrafish, the light stimulus is usually delivered by a fiber optic cable. The purpose of this study was to determine whether the angle of incidence of the stimulus light from the fiber optic cable will affect the amplitudes and implicit times of the ERGs of zebrafish larvae. The larvae were positioned on their side with the right eye pointed upward. The light stimuli were delivered by a fiber optic cable from three directions of the larvae: frontal 0° (F0°), dorsal 30°(D30°), and ventral 30°(V30°). Photopic ERGs were recorded from 16 larvae at age 5–6 days post-fertilization. Our results showed that the mean amplitude of the b-wave elicited at D30° and V30° stimulation was significantly smaller than that elicited at F0° stimulation (P = 0.014 and P = 0.019, respectively). In addition, the mean amplitude of the d-wave elicited at D30° and V30° stimulation was significantly smaller than that elicited at F0° stimulation (P < 0.0001 and P = 0.015, respectively). However, the difference between the b-wave amplitudes elicited at D30° and V30° stimuli were not significant (P = 0.98), and the d-wave amplitudes were also not significantly different (P = 0.20). The average b-wave amplitudes elicited at D30° stimulation was 84.6 ± 15.7% and V30° stimulation was 84.8 ± 17.4% relative to that of F0° stimulation. The average d-wave amplitudes elicited by D30° stimulation was 85.5 ± 15.2% and by V30° stimulation was 79.0 ± 11.0% relative to that of F0° stimulation. The differences in the implicit times of the b- and d-wave elicited by the different directions of stimulation were not significant (P = 0.52 and P = 0.14, respectively). We conclude that the amplitude of the photopic ERGs is affected by the angle of the incident light. Thus, it would be better to use ganzfeld stimuli to elicit maximum b- and d-wave amplitudes of the photopic ERGs of zebrafish larvae.

Enhancement of the Inner Foveal Response of Young Adults with Extended-Depth-of-Focus Contact Lens for Myopia Management.

Myopia management contact lenses have been shown to successfully decrease the rate of eye elongation in children by changing the peripheral refractive profile of the retina. Despite the efforts of the scientific community, the retinal response mechanism to defocus is still unknown. The purpose of this study was to evaluate the local electrophysiological response of the retina with a myopia control contact lens (CL) compared to a single-vision CL of the same material. The retinal electrical activity and peripheral refraction of 16 eyes (16 subjects, 27.5 ± 5.7 years, 13 females and 3 males) with myopia between -0.75 D and -6.00 D (astigmatism < 1.00 D) were assessed with two CLs (Filcon 5B): a single-vision (SV) CL and an extended-depth-of-focus (EDOF) CL used for myopia management. The peripheral refraction was assessed with an open-field WAM-5500 auto-refractometer/keratometer in four meridians separated by 45° at 2.50 m distance. The global-flash multifocal electroretinogram (gf-mfERG) was recorded with the Reti-port/scan21 (Roland Consult) using a stimulus of 61 hexagons. The implicit time (in milliseconds) and response density (RD, in nV/deg2) of the direct (DC) and induced (IC) components were used for comparison between lenses in physiological pupil conditions. Although the EDOF decreased both the HCVA and the LCVA (one and two lines, respectively; p < 0.003), it still allowed a good VA. The EDOF lens induced a myopic shift in most retinal areas, with a higher and statistically significant effect on the nasal retina. No differences in the implicit times of the DC and IC components were observed between SV and EDOF. Compared with the SV, the EDOF lens showed a higher RD in the IC component in the foveal region (p = 0.032). In the remaining retinal areas, the EDOF evoked lower, non-statistically significant RD in both the DC and IC components. The EDOF myopia control CL enhanced the response of the inner layers of the fovea. This might suggest that, besides other mechanisms potentially involved, the central foveal retinal activity might be involved in the mechanism of myopia control with these lenses.

Early Alterations in Inner-Retina Neural and Glial Saturated Responses in Lens-Induced Myopia.

Myopic marmosets are known to exhibit significant inner retinal thinning compared to age-matched controls. The purpose of this study was to assess inner retinal activity in marmosets with lens-induced myopia compared to age-matched controls and evaluate its relationship with induced changes in refractive state and eye growth. Cycloplegic refractive error (Rx), vitreous chamber depth (VCD), and photopic full-field electroretinogram were measured in 14 marmosets treated binocularly with negative contact lenses compared to 9 untreated controls at different stages throughout the experimental period (from 74 to 369days of age). The implicit times of the a-, b-, d-, and photopic negative response (PhNR) waves, as well as the saturated amplitude (Vmax), semi-saturation constant (K), and slope (n) estimated from intensity-response functions fitted with Naka-Rushton equations were analyzed. Compared to controls, treated marmosets exhibited attenuated b-, d-, and PhNR waves Vmax amplitudes 7 to 14days into treatment before compensatory changes in refraction and eye growth occurred. At later time points, when treated marmosets had developed axial myopia, the amplitudes and implicit times of the b-, d-, and PhNR waves were similar between groups. In controls, the PhNR wave saturated amplitude increased as the b + d-wave Vmax increased. This trend was absent in treated marmosets. Marmosets induced with negative defocus exhibit early alterations in inner retinal saturated amplitudes compared to controls, prior to the development of compensatory myopia. These early ERG changes are independent of refraction and eye size and may reflect early changes in bipolar, ganglion, amacrine, or glial cell physiology prior to myopia development. The early changes in retinal function identified in the negative lens-treated marmosets may serve as clinical biomarkers to help identify children at risk of developing myopia.

Electroretinographical Analysis of the Effect of BGP-15 in Eyedrops for Compensating Global Ischemia-Reperfusion in the Eyes of Sprague Dawley Rats.

Retinal vascular diseases and consequential metabolic disturbances in the eye are major concerns for healthcare systems all around the world. BGP-15, a drug candidate small-molecule [O-(3-piperidino-2-hydroxy-1-propyl) nicotinic amidoxime dihydrochloride], has been formerly demonstrated by our workgroup to be retinoprotective both in the short and long term. Based on these results, the present study was performed to investigate the efficacy of BGP in an eyedrop formulation containing sulfobutylether-β-cyclodextrin (SBECD), which is a solubility enhancer as well. Electroretinographical evaluations were carried out and BGP was demonstrated to improve both scotopic and photopic retinal a- and b-waves, shorten their implicit times and restore oscillatory potentials after ischemia-reperfusion. It was also observed to counteract retinal thinning after ischemia-reperfusion in the eyes of Sprague Dawley rats. This small-molecule drug candidate is able to compensate for experimental global eye ischemia-reperfusion injury elicited by ligation of blood vessels in rats. We successfully demonstrated that BGP is able to exert its protective effects on the retina even if administered in the form of eyedrops.

Paediatric norms for photopic electroretinogram testing based on a large cohort of Chinese preschool children

ObjectiveFull-field electroretinogram (ffERG) is an objective test to determine the electroretinal activities in response to light stimulation for investigating retinal physiology and diagnosing retinal diseases. This study aimed to establish...

Assessing the pattern electroretinogram as a proxy measure for dopamine in the context of iron deficiency

ABSTRACT Objectives Animal studies have suggested that dietary iron deficiency (ID) negatively affects dopamine (DA) synthesis and re-uptake, which in turn negatively affects memory and cognition. This study was intended to assess whether the pattern electroretinogram (pattern ERG) could be used as an indirect measure of DA in college-age women with and without ID by determining the extent to which features of the ERG were sensitive to iron status and were related to other indirect measures of DA. Methods The pattern ERG was measured in 21 iron deficient non-anemic (IDNA) and 21 iron sufficient (IS) women, who also performed a contrast detection and probabilistic selection task, both with concurrent electroencephalography (EEG). Both spontaneous and task-related blink rates were also measured. Results The implicit times of the A- and B-waves were significantly longer for the IDNA than for the IS women. Both the amplitudes and implicit times of the A- and B-waves were significantly correlated with levels of serum ferritin (sFt). Only the amplitude of the A-wave was correlated with spontaneous blink rate. It was possible to accurately identify a woman’s iron status solely on the basis of the implicit time of the B-wave. Finally, the implicit times of the ERG features mediated the relationship between iron levels and accuracy in the probabilistic selection task. Conclusions Results suggest the utility of the pattern ERG in testing the hypothesis that iron deficiency affects DA levels in humans and that this may be one of the mechanisms by which iron deficiency negatively affects cognition.

Retinal response to two commercially available contact lenses for myopia control

Aims/Purpose: Myopia control contact lenses (CLs) have shown optimistic results in eye growth retention in children. However, it is still unknown the retinal mechanisms of defocus detection. This study evaluated the electrophysiological response of the retina with two myopia control CLs, compared to single‐vision CLs.Methods: High‐contrast visual acuity (VA) and the retinal activity of 16 eyes (16 subjects, 27.5 ± 5.7 years, 12 female) with myopia (from −0.75 to −6.00 D, astigmatism &gt;1.00 D) were assessed with two single‐vision CLs (Omafilcon A – SVo – and Filcon 5B – SVf) and two myopia control CLs (dual‐focus – DF, Omafilcon A – and extended‐depth‐of‐focus – EDOF, Filcon 5B). The global‐flash multifocal electroretinogram (gf‐mfERG) was recorded with the Reti‐port/scan21 (Roland Consult) with a 61‐hexagons stimulus in physiological pupil conditions. The implicit time (milliseconds) and response density (nV/deg2) of the direct (DC) and induced (IC) components were compared between CLs of matching material.Results: All CLs showed similar VA (p &gt; 0.050). The implicit times did not show statistically significant differences. DF showed higher response density of both DC and IC components at all retinal areas, with a statistically significant difference in the parafoveal DC component (difference of 2.77 [6.23–1.44] nV/deg2, p = 0.038), compared with the SVo. EDOF showed a higher response density of about 13.31 [23.88–3.85] nV/deg2 (p = 0.032) in the foveal IC component, compared with the SVf. The remaining retinal areas did not show statistically significant differences.Conclusions: The retina seems to respond differently to distinct CL's optical designs. The two myopia control CLs increased the electrophysiological response of the retina, but with different effects, without affecting the implicit time of the response. Multifocal contact lenses with peripheral defocus induce different foveal and parafoveal activities that might be involved in the mechanism of myopia control.

Peripheral refraction and retinal activity with dual focus contact lenses for myopia control

Aims/Purpose: Contact lenses (CLs) for myopia control have shown optimistic eye growth retention in children but, the retinal mechanisms of defocus still unclear. This work evaluated the retinal response and peripheral refraction with a soft CL for myopia management in myopic eyes.Methods: The visual acuity (VA), peripheral refraction and the retinal electrical activity were obtained from sixteen myopic (between −0.75 D and − 6.00 D, astigmatism &gt;1.00 D) subjects (27.5 ± 5.7 years, 12 female), with two material‐matched CLs (Omafilcon A): a single‐vision CL (SV) and a myopia management dual‐focus CL (DF). Peripheral refraction was assessed with an open‐field autorefractometer (WAM‐5500, GrandSeiko Co. Lt) in four meridians separated by 45° at 2.50 meters distance. The global‐flash multifocal electroretinogram (gf‐mfERG) was recorded with the Reti‐port/scan21 (Roland Consult) using a stimulus of 61‐hexagons. The implicit time and response density (in nV/deg2) of the direct (DC) and induced (IC) components were analysed. Only the data of a single eye per subject was randomly used for analysis.Results: The two CLs designs showed similar VA (p &gt; 0.050). The DF induced a myopic shift of the SV peripheral refraction in most retinal eccentricities (p &lt; 0.050). There were no differences in the implicit times of the retinal response between CLs designs. The DF increased the response density of both DC and IC components at all retinal areas, with a statistically significant difference in the parafoveal DC component (median difference of 2.77 [6.23–1.44] nV/deg2, p = 0.038).Conclusions: The results showed that the retina responds differently to a SV and a DF CLs. The myopia management CL increased the electrophysiological response of the retina without affecting the time domain of the response. Besides other mechanisms potentially involved, the foveal and parafoveal retinal activities might be involved in the mechanism of myopia control with these lenses.

Subclinical Ocular Changes after Intravitreal Injections of Different Anti-VEGF Agents for Neovascular Age-Related Macular Degeneration

Intraocular inflammations (IOIs) have been reported to occur after intravitreal injections of brolucizumab, and one of their causes has been suggested to be drug-specific features. We evaluated the anterior chamber by the aqueous flare value (AFV) and the retina by flicker electroretinography (ERG) after the initial intravitreal injection of aflibercept (IVA), brolucizumab (IVBr), or faricimab (IVF) for neovascular age-related macular degeneration (nAMD). The AFV and flicker ERGs were determined before, 2 weeks after, and 4 weeks after the injections in 14 eyes of 14 patients for each drug. After the injections, none of the patients had an IOI, but the AFV increased significantly in the IVA and IVF groups. The increase in the IVF group was +4.6 photon count/ms, which was significantly greater than in the other groups, but was not clinically significant. The implicit time was significantly prolonged in the IVBr group but unchanged in the IVA and IVF groups. These results suggest that brolucizumab, administered at high molar doses, may cause transient retinal disturbances that are not detectable by general ophthalmologic examinations but affect the implicit ERG times.

Hydrogen Peroxide Affects the Electroretinogram of Isolated Perfused Rat Retina

Purpose To evaluate the effects of H2O2 as an oxidant on the electroretinogram (ERG) in isolated rat retina. Methods Retinas were isolated from rat eyes and perfused with a nutrient solution. ERGs were recorded every 3 min. Once the signal was at a steady state, H2O2 was added to the perfusion solution. Results H2O2 caused instantaneous and transient changes in amplitudes and implicit times of the ERG, followed by changes in retinal survival curves. H2O2 0.2 mM produced a rapid increase in b-wave amplitude, followed by a return to the initial value and a survival curve above the control (without H2O2). A slight increase in a-wave was observed, followed by a decrease and a recovery above the control. The slow PIII decreased and then recovered to the initial value. H2O2 0.6 mM induced a small increase in b-wave amplitude, followed by a rapid decrease without recovery. The a-wave and slow PIII decreased rapidly without recovery. The implicit times of the a-wave and b-wave increased moderately with a low dose of H2O2, whereas they significantly increased with a high dose. Whatever the dose, the slow PIII implicit time increased significantly, followed by a return to the initial value. Barium increased the a-wave and b-wave, and then H2O2 reduced the two waves with a stronger effect on the a-wave. Aspartate and barium isolated the fast PIII, which decreased after H2O2 application. Conclusions H2O2 affects retinal function as shown by ERGs in isolated rat retina. The response differs with the dose of H2O2, suggesting that mechanisms underlying the action at low doses might be different from those at high doses. Our results also suggest an effect of H2O2 on ionic currents and/or neurotransmitter releases involved in the generation of the ERG and indicate a more pronounced effect on photoreceptors than on postsynaptic cells.

Suprachoroidal spheroidal mesenchymal stem cell implantation in retinitis pigmentosa: clinical results of 6 months follow-up

PurposeThis prospective clinical case series aimed to evaluate the effect of suprachoroidal implantation of mesenchymal stem cells (MSCs) in the form of spheroids as a stem cell therapy for retinitis pigmentosa (RP) patients with relatively good visual acuity.MethodsFifteen eyes of 15 patients with RP who received suprachoroidal implantation of MSCs in the form of spheroids were included. Best-corrected visual acuity (BCVA), 10–2 and 30–2 visual field examination and multifocal electroretinography (mfERG) recordings were recorded at baseline, postoperative 1st, 3rd and 6th months during follow-up.ResultsBaseline median BCVA of RP patients was 1.30 (1.00–2.00) logMAR. BCVA has improved to 1.00 (0.50–1.30), 0.80 (0.40–1.30) and 0.80 (0.40–1.30) at the postoperative 1st, 3rd and 6th months, respectively. The improvements from baseline to the 3rd and 6th months were statistically significant (p = 0.03 and p < 0.001, respectively). In the 30–2 VF test, median MD was significantly improved at the 6th month compared to baseline (p = 0.030). In the 10–2 VF test, the median MD value was significantly different at the 6th month compared to the baseline (p = 0.043). The PSD value of the 10–2 VF test was significantly different at the 6th month compared to the 3rd month (p = 0.043). The amplitudes of P1 waves in < 2°, 5°–10° and 10°–15° rings improved significantly at the postoperative 6th month (p = 0.014, p = 0.018 and p = 0.017, respectively). There was also a statistically significant improvement in implicit times of P1 waves in 10°–15° ring at the postoperative 6th month (p = 0.004).ConclusionSuprachoroidal implantation of MSCs in the form of spheroids as a stem cell therapy for RP patients with relatively good visual acuity has an improving effect on BCVA, VF and mfERG recordings during the 6-month follow-up period. Spheroidal MSCs with enhanced effects may be more successful in preventing apoptosis and improving retinal tissue healing in RP patients.

Assessment of Macular Function by Multifocal Electroretinography Following Idiopathic Epiretinal Membrane Surgery with Internal Limiting Membrane Peeling

Purpose To evaluate macular function before and after vitrectomy for idiopathic epiretinal membrane (ERM) with internal limiting membrane (ILM) peeling by multifocal electroretinography (mfERG) and their correlations with visual acuity (VA) and central subfoveal thickness (CST) by optical coherence tomography (OCT). Settings and Design A prospective interventional case series of 15 eyes with idiopathic ERM of 14 patients who underwent pars plana vitrectomy (PPV) for ERM removal with ILM peeling. Methods Multifocal electroretinography (mfERG) and OCT were performed preoperatively and one month after surgery. The response amplitude densities and implicit times of mfERG were analyzed. Correlation analyses among visual acuity, CST and mfERG values in the five concentric rings were performed. Results The first order responses of mfERG recorded preoperatively showed diffuse reduction in P1 amplitudes in all 5 rings with no statistically significant differences in mfERG responses after ERM surgery. Correlation coefficients showed a significant correlation between postoperative VA and P1 amplitude of ring 2 (P = 0.005). There was no significant correlation between postoperative CST and P1 amplitude for all rings Conclusions The mfERG responses in eyes with idiopathic ERM show macular function abnormalities and correlate with VA after surgery. The residual retinal distortion along with the damage to inner retinal layers and Muller cell dysfunction associated with ILM peeling affect the mfERG responses after surgery. The incorporation of mfERG into the pre- and post-operative assessment of patients with iERM, allow for identification of functional impairment and predict visual outcomes.

Utility of Light-Adapted Full-Field Electroretinogram ON and OFF Responses for Detecting Glaucomatous Functional Damage.

To compare parameters of electroretinogram (ERG) responses for their ability to detect functional loss in early stages of nonhuman primate (NHP) experimental glaucoma (EG), including photopic negative responses (PhNR) to a standard brief red flash on a blue background (R/B) and 200-ms-long R/B and white-on-white (W/W) flashes, to W/W flicker stimuli (5-50Hz), and to a dark-adapted intensity series. Light-adapted ERGs were recorded in 12 anesthetized monkeys with unilateral EG. Amplitudes and implicit times of the a-wave, b-wave, and d-wave were measured, as well as amplitudes of PhNRs and oscillatory potentials for flash onset and offset. Flicker ERGs were measured using peak-trough and fundamental frequency analyses. Dark-adapted ERG parameters were modeled by Naka-Rushton relationships. Only PhNR amplitudes were significantly reduced in EG eyes compared to fellow control (FC) eyes. The d-wave implicit time was delayed in EG versus FC eyes only for the W/W long flash, but in all eyes it was 10 to 20 ms slower for R/B versus the W/W condition. Flicker ERGs were <0.5 ms delayed in EG versus FC overall, but amplitudes were affected only at 5Hz. The brief R/B PhNR amplitude had the highest sensitivity to detect EG and strongest correlation to parameters of structural damage. The PhNR to the standard brief R/B stimulus was best for detecting and following early-stage functional loss in NHP EG. These results suggest that there would be no benefit in using longer duration flashes to separate onset and offset responses for clinical management of glaucoma.

Retinal dysfunction in Parkinson's disease-results of the extended protocol for photopic negative response (PHNR) full-field electroretinogram (ERG).

We investigated whether the photopic negative response (PhNR) in the electroretinogram (ERG) was affected in Parkinson's disease (PD) patients and whether it was associated with retinal changes on optical coherence tomography (OCT). Thirty-two patients with PD and 31 age and sex-matched healthy controls from a single tertiary centre were included in the study. Hoehn and Yahr scale scores and the presence of REM sleep behaviour were recorded. PhNR, a-wave and b-wave responses in photopic ERG (red on blue background) and retinal layer thicknesses in OCT were obtained. The mean age was 61 ± 10.4 in the PD group (female/male: 18/14) and 60.9 ± 7 in the control group (female/male: 18/13). The amplitudes of the PhNR, a- and b-waves in the ERG were significantly decreased in the PD group, but the implicit times were not significantly different. BCVA was significantly correlated with Hoehn and Yahr scores (p < 0.001, r = -0.596). There was a significant correlation between BCVA and a-wave amplitude (p = 0.047, r = -0.251). On OCT analysis, the thickness of the nasal INL was increased, and the temporal and inferior OPL and temporal peripapillary RNFL were decreased in the PD group compared to healthy controls (p = 0.032, p = 0.002, p = 0.016 and p = 0.012, respectively). This study demonstrated reduced a-wave, b-wave and PhNR-wave amplitudes on ERG measurements in PD patients. These findings suggest that the whole ERG response, not just the PhNR, is attenuated in patient with PD, suggesting a possible involvement of the visual system in the disease.

An ERP measure of non-conscious memory reveals dissociable implicit processes in human recognition using an open-source automated analytic pipeline.

Non-conscious processing of human memory has traditionally been difficult to objectively measure and thus understand. A prior study on a group of hippocampal amnesia (N = 3) patients and healthy controls (N = 6) used a novel procedure for capturing neural correlates of implicit memory using event-related potentials (ERPs): old and new items were equated for varying levels of memory awareness, with ERP differences observed from 400 to 800 ms in bilateral parietal regions that were hippocampal-dependent. The current investigation sought to address the limitations of that study by increasing the sample of healthy subjects (N = 54), applying new controls for construct validity, and developing an improved, open-source tool for automated analysis of the procedure used for equating levels of memory awareness. Results faithfully reproduced prior ERP findings of parietal effects that a series of systematic control analyses validated were not contributed to nor contaminated by explicit memory. Implicit memory effects extended from 600 to 1000 ms, localized to right parietal sites. These ERP effects were found to be behaviorally relevant and specific in predicting implicit memory response times, and were topographically dissociable from other traditional ERP measures of implicit memory (miss vs. correct rejections) that instead occurred in left parietal regions. Results suggest first that equating for reported awareness of memory strength is a valid, powerful new method for revealing neural correlates of non-conscious human memory, and second, behavioral correlations suggest that these implicit effects reflect a pure form of priming, whereas misses represent fluency leading to the subjective experience of familiarity.