A-wave Amplitude Research Articles

Infliximab exerts a dose-dependent effect on retinal safety in the albino rabbit.

To assess the retinal toxicity of an intravitreal injection of infliximab, a monoclonal antibody to tumor necrosis factor α, in a rabbit model. Two groups of adult albino rabbits (n=5) received intravitreal injections of infliximab (0.1ml) in the study eye and balanced salt solution (BSS, 0.1ml) in the control eye at baseline. Group 1 was administered with 1.5mg/0.1ml, and group 2 was injected with 7.5mg/0.1ml of infliximab solution. Electroretinography (ERG) was performed at baseline and at 1, 7, 30, and 45days after the injection. Visual evoked potentials (VEPs) were recorded at 7 and 45days after the injection. After the last electrophysiological assessment, the rabbits were euthanized and retinal histopathology and immunhistochemistry for glial fibrillary acidic protein (GFAP) were performed. ERG responses demonstrated no significant deficit in retinal function in eyes injected with infliximab. Mean dark-adapted a-wave and b-wave maximal amplitude and semi-saturation constant values at baseline and throughout the 45days of follow-up after the injection indicated no remarkable difference in outer retinal function between the control and experimental eyes. VEP responses were similar at each time point (7 and 45days). No difference was seen in retinal histopathology and immunocytochemistry sections in eyes receiving the 1.5mg/0.1ml dose compared to the control eyes. However, increased GFAP labeling in retinal Müller cells was detected in rabbit eyes treated with the 7.5mg/0.1ml dose. Intravitreal injection of 1.5mg/0.1ml infliximab dose has no toxic effect on the integrity (functional or structural) of the retina in rabbits. A higher dose of 7.5mg/0.1ml may be slightly toxic as suggested by positive Müller cell GFAP expression. Additional studies of retinal toxicity at higher doses and after multiple injections are needed to establish the retinal safety of intravitreal infliximab therapy in humans.

Neural Responses to Multielectrode Stimulation of Healthy and Degenerate Retina.

Simultaneous stimulation of multiple retinal electrodes in normally sighted animals shows promise in improving the resolution of retinal prostheses. However, the effects of simultaneous stimulation on degenerate retinae remain unknown. Therefore, we investigated the characteristics of cortical responses to multielectrode stimulation of the degenerate retina. Four adult cats were bilaterally implanted with retinal electrode arrays in the suprachoroidal space after unilateral adenosine triphosphate (ATP)-induced retinal photoreceptor degeneration. Functional and structural changes were characterized by using electroretinogram a-wave amplitude and optical coherence tomography. Multiunit activity was recorded from both hemispheres of the visual cortex. Responses to single- and multielectrode stimulation of the ATP-injected and fellow control eyes were characterized and compared. The retinae of ATP-injected eyes displayed structural and functional changes consistent with mid- to late-stage photoreceptor degeneration and remodeling. Responses to multielectrode stimulation of the ATP-injected eyes exhibited shortened latencies, lower saturated spike counts, and higher thresholds, compared to stimulation of the fellow control eyes. Electrical receptive field sizes were significantly larger in the ATP-injected eye than in the control eye, and positively correlated with the extent of degeneration. Significant differences exist between cortical responses to stimulation of healthy and degenerate retinae. Our results highlight the importance of using a retinal degeneration model when evaluating the efficacy of novel stimulation paradigms.

Protective effect of resveratrol against light-induced retinal degeneration in aged SAMP8 mice.

PurposeThe purpose of this study was to determine the protective effects of Resveratrol (RESV) on acute bright light-induced retinal degeneration in aged senescence accelerated mouse strain.MethodsTen three-month-old male SAMP8 mice (prone to aging) were randomly assigned to two experimental dietary groups: one untreated group and one RESV treatment group (n=20 eyes for each group). After 30 days of treatment, mice were exposed to intense bright light. Ten male SAMR1 mice (resistant to aging) served as control (n=20 eyes). The protective effects of RESV administration on light-induced retinal degeneration in SAMP8 strain as well as the effect of bright light damage in the retinas of SAMP8 mice were analyzed by electroretinography (ERG), retinal histology, mRNA, protein and lipid profile.Results68%-85% of a-wave amplitude and 72%-92% of b-wave amplitude were persevered by RESV in SAMP8 mice that were exposed to light damage. Also, RESV preserved their photoreceptor nuclei. mRNA expression of neuroprotective factors leukemia inhibitory factor (LIF), brain derived neurotrophic factor (BDNF), oncostatin M (OSM), cardiotrophin 1(CT-1) and cardiotrophin-like cytokine (CLC) were up-regulated 28, 8, 7, 5 and 9-fold in SAMP8 mice after RESV treatment. In addition, RESV could suppress the NF-κB pathway by down-regulating the expression of pIκB. Light damage led to increase of saturated FA, monoenoic FA, n6 PUFA and n6/n3 ratio and decrease of Docosahexaenoic acid (DHA). There was no significant difference on DHA and the ratio of n6/n3-FA between the untreated and RESV treated SAMP8 mice.ConclusionsCollectively, our study provides evidence that RESV prevents light-induced retinal damage associated with aging.

Effect of carotid endarterectomy on retinal function in asymptomatic patients with hemodynamically significant carotid artery stenosis.

INTRODUCTION The corrective effect of carotid endarterectomy (CEA) on impaired ophthalmic artery flow in patients with significant internal carotid artery (ICA) stenosis presenting with ocular ischemic syndrome (ie, symptomatic patients) is well established. However, there is no clear evidence regarding the efficacy of CEA for improvement of neuroretinal function in patients without symptoms of ocular ischemic syndrome. OBJECTIVES We aimed to determine the effects of CEA on retinal function in asymptomatic patients with hemodynamically significant ICA stenosis. PATIENTS AND METHODS We enrolled 46 patients with ICA stenosis referred for CEA. Full-field electroretinogram (ERG), pattern ERG, and pattern visual evoked potentials, as well as optical coherence tomography and ophthalmologic examination of both eyes were performed 1 day before and 3 months after CEA. We analyzed eyes ipsilateral (EIE) and contralateral (ECE) to CEA. RESULTS We observed an increase in several ERG wave parameters in both eye groups, compared with baseline values: rod b-wave amplitudes (P <0.00001 for EIE and P = 0.0001 for ECE); rod-cone a-wave (P = 0.02 for EIE) and b-wave (P = 0.001 for EIE and P = 0.01 for ECE) amplitudes; cone single flash a-wave (P = 0.05 for EIE and P = 0.004 for ECE) and b-wave (P <0.0001 for EIE and P <0.0001 for ECE) amplitudes; cone 30-Hz flicker amplitudes (P = 0.0003 for EIE and P <0.0001 for ECE); and oscillatory potential wave index amplitudes (P <0.00001 for EIE). CONCLUSIONS The amplitudes of the standard full-field ERG were significantly increased following CEA in EIE and, to a lesser extent, in ECE. Multimodality ERG may represent a unique tool for investigating the effects of carotid revascularization on neuroretinal function in asymptomatic patients with ICA stenosis.

Electroretinogram Findings in Early-Stage Sickle Cell Retinopathy According to Hemoglobin Type.

Although extensive clinical research has been performed on structural analysis of sickle cell (SC) retinopathy, functional aspects have been poorly investigated. Our purpose was to report full-field electroretinogram (ffERG) findings in patients with early SC retinopathy according to the following hemoglobin types: HbSS or HbSC (homozygous or heterozygous mutations, respectively). In this monocentric retrospective observational study, patients affected by nonproliferative SC retinopathy were included from November 2014 to April 2016. Patients were separated into one of the following three groups: HbSS, HbSC, and control. All groups underwent full ophthalmologic examination (fundus examination) and ffERG. For SC patients, additional imaging testing was also performed (fluorescein angiography and spectral domain optical coherence tomography). A total of 24 eyes from 12 patients (6 HbSS and 6 HbSC) and 12 eyes from 6 controls were included. The HbSS group exhibited a dramatic decrease of the b-wave amplitudes for all dark-adapted (DA) ffERG responses when compared with the control group (P = 0.02, P = 0.003, P = 0.005, respectively, after DA 0.01, DA 3.0, and DA 10.0 cd.s.m-2 stimulations) and decreased a-wave amplitudes for light-adapted responses (P = 0.03 after light-adapted 3.0 cd.s.m-2 stimulations). The a-Wave amplitudes were significantly reduced for all dark-adapted and light-adapted responses in HbSC group compared to the control group (P = 0.03, P = 0.01, P = 0.03, respectively, after DA 3.0, DA 10.0, and light-adapted 3.0 cd.s.m-2 stimulations). The HbSS+HbSC groups presented decreased a-wave amplitudes for DA and light-adapted responses and decreased b-wave amplitude after DA 0.01 and 10.0 cd.s.m-2 stimulations when compared to the control group. These results could suggest an early involvement of the inner retinal cells in the disease process in HbSS patients and of the outer retinal cells in HbSC patients. This could provide new insights on the pathophysiology of the retinal affection in HbSS/HbSC SC disease.

The protective effect of erythropoietin on the experimental light-induced retinal degeneration of rat

Objective To investigate the protective effect of erythropoietin(EPO) on the structure and function of light-induced damage in rat retina. Methods The animal model of light-induced retinal degeneration was made. Thirty-six SD rats were randomly divided into experimental group, peritoneal injection with EPO and control group, peritoneal injection with the same amount of normal saline. The EPO and EPOR expression were observed in two groups. The structure and thickness of the retina and ERG before and after light explosure were observed. Results The gray value of EPO and EPOR expression in any layer of the retina reached peak value at 24 hours after light explosure.EPO and EPOR expression at 6, 24 and 72 hours were higher than that of before light explosure. The difference were statistically significant(P=0.002, 0.000, 0.000; P=0.001, 0.000, 0.000). Seven days after light explosure, the outer retina thickness of two groups markedly reduced(P=0.000), but the reduction of outer retina thickness in experimental group was less than that in control group(P=0.000). The amplitude of a-wave and b-wave in two groups decreased remarkably at 1 day, 1 week and 2 weeks after light explosure, but the amplitude of a-wave and b-wave in experimental group was higher than those in control group(P=0.013-0.039). Conclusion Endogenous EPO and EPOR express increasingly after light damage. Systemic exogenous EPO plays a protective role in light-induced damage in retina. Key words: Erythropoietin; Animal model; Retina; Light-induced damage

Improved retinal function in RCS rats after suppressing the over-activation of mGluR5

Müller cells maintain retinal synaptic homeostasis by taking up glutamate from the synaptic cleft and transporting glutamine back to the neurons. To study the interaction between Müller cells and photoreceptors, we injected either DL-α-aminoadipate or L-methionine sulfoximine–both inhibitors of glutamine synthetase–subretinally in rats. Following injection, the a-wave of the electroretinogram (ERG) was attenuated, and metabotropic glutamate receptor 5 (mGluR5) was activated. Selective antagonism of mGluR5 by 2-methyl-6-(phenylethynyl)-pyridine increased the ERG a-wave amplitude and also increased rhodopsin expression. Conversely, activation of mGluR5 by the agonist, (R,S)-2-chloro-5-hydroxyphenylglycine, decreased both the a-wave amplitude and rhodopsin expression, but upregulated expression of Gq alpha subunit and phospholipase C βIII. Overexpression of mGluR5 reduced the inward-rectifying potassium ion channel (Kir) current and decreased the expression of Kir4.1 and aquaporin-4 (AQP4). Further experiments indicated that mGluR5 formed a macromolecular complex with these two membrane channels. Lastly, increased expression of mGluR5 was found in Royal College of Surgeons rats–a model of retinitis pigmentosa (RP). Inhibition of mGluR5 in this model restored the amplitude of ERG features, and reduced the expression of glial fibrillary acidic protein. These results suggest that mGluR5 may be worth considering as a potential therapeutic target in RP.

Electrophysiological findings show generalised post-photoreceptoral deficiency in macular telangiectasia type 2

BackgroundPhotoreceptor damage, reported in single observations, has been suggested to contribute to the disease pathogenesis in macular telangiectasia type 2 (MacTel2). The purpose of this study was to ascertain whether...

Specific Alleles of CLN7/MFSD8, a Protein That Localizes to Photoreceptor Synaptic Terminals, Cause a Spectrum of Nonsyndromic Retinal Dystrophy

Recessive mutations in CLN7/MFSD8 usually cause variant late-infantile onset neuronal ceroid lipofuscinosis (vLINCL), a poorly understood neurodegenerative condition, though mutations may also cause nonsyndromic maculopathy. A series of 12 patients with nonsyndromic retinopathy due to novel CLN7/MFSD8 mutation combinations were investigated in this study. Affected patients and their family members were recruited in ophthalmic clinics at each center where they were examined by retinal imaging and detailed electrophysiology. Whole exome or genome next generation sequencing was performed on genomic DNA from at least one affected family member. Immunofluorescence confocal microscopy of murine retina cross-sections were used to localize the protein. Compound heterozygous alleles were identified in six cases, one of which was always p.Glu336Gln. Such combinations resulted in isolated macular disease. Six further cases were homozygous for the variant p.Met454Thr, identified as a founder mutation of South Asian origin. Those patients had widespread generalized retinal disease, characterized by electroretinography as a rod-cone dystrophy with severe macular involvement. In addition, the photopic single flash electroretinograms demonstrated a reduced b- to a-wave amplitude ratio, suggesting dysfunction occurring after phototransduction. Immunohistology identified MFSD8 in the outer plexiform layer of the retina, a site rich in photoreceptor synapses. This study highlights a hierarchy of MFSD8 variant severity, predicting three consequences of mutation: (1) nonsyndromic localized maculopathy, (2) nonsyndromic widespread retinopathy, or (3) syndromic neurological disease. The data also shed light on the underlying pathogenesis by implicating the photoreceptor synaptic terminals as the major site of retinal disease.

Corneal Potential Maps Measured With Multi-Electrode Electroretinography in Rat Eyes With Experimental Lesions.

Conventional full-field flash electroretinography (ERG) yields a single response waveform that can be useful in the early detection and diagnosis of many diseases affecting the retina. It is an objective measurement that probes the entire retina. However, localized areas of dysfunction have relatively small influence on ERG amplitudes compared to normal ranges. Here we evaluate the use of corneal potential maps obtained in response to full-field flash stimuli for sensitivity to local areas of retinal damage. A contact lens electrode array was used to record 25 ERG waveforms simultaneously following saturating full-field flash stimuli (multi-electrode electroretinography, meERG) in rats. Waveforms were evaluated for a-wave and b-wave amplitudes; these values were normalized and further evaluated for spatial differences across the corneal surface. Cluster analysis and a support vector machine approach were used to classify meERG responses from healthy eyes and eyes with central (photocoagulation) or peripheral (cryocoagulation) experimental lesions. A normative normalized corneal potential map was obtained from healthy eyes (n = 26). Corneal potential maps from eyes with experimental lesions (n = 13) could be classified with sensitivity and specificity of approximately 80% based solely on the normalized spatial distribution of corneal potentials, that is, with no knowledge of absolute amplitudes. Corneal potential maps obtained in response to full-field flash stimuli are altered in eyes with scotomas in the central and far-peripheral retina. The meERG approach yields useful spatial information following a single brief flash, analogous to body-surface potential maps used to evaluate heart and brain.

Relative Genetic and Environmental Contributions to Variations in Human Retinal Electrical Responses Quantified in a Twin Study

PurposeTo estimate heritability of parameters of human retinal electrophysiology and to explore which parameters change with age.DesignProspective, classic twin study.ParticipantsAdult monozygotic and dizygotic twin pairs recruited from the TwinsUK cohort.MethodsElectroretinogram responses were recorded using conductive fiber electrodes in response to stimuli incorporating standards set by the International Society for the Clinical Electrophysiology of Vision. These parameters were extracted; in addition, photopic negative-response (PhNR; originating from retinal ganglion cells) and i-wave components were extracted from responses to the photopic single flash. Parameter values were averaged from both eyes.Main Outcome MeasuresMean values were calculated for the cohort. Correlation coefficients with age were calculated (averaging parameters from both twins from each pair). Coefficients of intrapair correlation were calculated for monozygotic and dizygotic twins. Age-adjusted heritability estimates were derived using standard maximum likelihood structural equation twin modeling.ResultsResponses were recorded from 210 participants in total (59 monozygotic and 46 dizygotic twin pairs). Ninety-three percent were women. Mean age for the cohort was 62.4 years (standard deviation, 11.4 years). In general, response amplitudes correlated negatively, and implicit times positively, with age. Correlations were statistically significant (P < 0.05) and moderate or strong (coefficient, >0.35) for the following parameters: scotopic standard and bright-flash a-wave implicit times, photopic 30-Hz flicker and single-flash b-wave implicit times, and PhNR and i-wave implicit times. Intrapair correlations were higher for monozygotic than dizygotic twins, suggesting important genetic influences. Age-adjusted estimates of heritability were significant for all parameters (except scotopic dim-flash b-wave implicit time), ranging from 0.34 to 0.85. Highest estimates were for photopic single-flash a-wave and b-wave amplitudes (0.84 and 0.85, respectively).ConclusionsThis study explored heritability of retinal electrophysiologic parameters and included measurements reflecting ganglion cell function. Most parameters showed significant heritability, indicating that genetic factors are important, determining up to 85% of the variance in some cone system response parameters. Scotopic responses tended to show lower heritability (possibly relating to greater rod system susceptibility to environmental factors). Future studies can explore the identity of these genetic factors, improving our understanding of how they shape retinal function.

Ophthalmic Evaluation in Beta-Thalassemia.

To determine the association of ocular manifestations in beta-thalassemia with the patient's age, blood transfusion requirements, average serum ferritin and dose and duration of iron chelation therapy. Sixty multi-transfused beta thalassemia patients of 12 to 18 y of age on chelation therapy were included in this cross-sectional analysis. Structural and functional evaluation of the retina was done using Optical coherence tomography (OCT) and Electroretinography (ERG), including flash ERG and Pattern ERG (PERG). Routine ophthalmic examination and B scan of the eye was also done. Flash ERG a-waves and b-waves were recorded, however only a-wave amplitude was evaluated. Pattern ERG n35, n95 and p50 waves were recorded and p50 wave amplitude was evaluated. The a-wave on flash and p50 on pattern waves represent retinal photoreceptor epithelium (RPE) photoreceptor response, which is mainly affected in beta-thalassemia. Ocular changes were detected in 38.3% and a significant correlation was noted with increase in age (p=0.045) but not with serum ferritin, transfusion requirements or chelation therapy. Refractive errors were found in 14 cases (23%), such as myopia with astigmatism in 13 (21.7%) and only myopia in 6 subjects (10%). OCT abnormality was noted in 1 patient (1.7%) who had thinning of central retina; right eye 132μm and left eye 146μm (n>200μm). Abnormalities were noted in a-wave amplitude on flash ERG in 20% of cases, while reduced p50 amplitude on PERG was noted in 15%. A significant correlation was noted between ocular findings and increase in age, but not with serum ferritin, transfusion requirements or chelation therapy. ERG appears to be a promising tool for screening patients with beta-thalassemia and can serve as a follow-up test for evaluating retinal function.

Electrophysiological assessment for early detection of retinal dysfunction in β-thalassemia major patients.

The purpose of this study was to assess the role of various diagnostic tests in early detection of retinal changes in β-thalassemia major patients. Thirty-eight visually asymptomatic β-thalassemia major patients receiving regular blood transfusions and iron-chelation therapy with deferoxamine (group A, n = 13), deferasirox (group B, n = 11) or deferoxamine with deferiprone (group C, n = 14) and fourteen age- and sex- matched healthy individuals were included in the study. All participants underwent ophthalmoscopy, full-field electroretinography (ERG), visual evoked potentials (VEP), multifocal electroretinography (mfERG), fundus autofluorescence (FAF) imaging and optical coherence tomography (OCT) scans. Retinal pigment epithelium changes were present in two cases. Scotopic ERG demonstrated decreased a-wave amplitude in groups A, B and C (p = 0.03, p = 0.002 and p = 0.002, respectively) and decreased b-wave amplitude in groups B and C (p = 0.002 and p = 0.01, respectively) compared to controls. Photopic ERG showed delayed b-wave latency in groups A and C (p = 0.03 and p = 0.03, respectively) ERG maximal combined response and VEP response did not differ between groups. MfERG showed reduced retinal response density in ring 1 in groups A, B, C (p < 0.001, p < 0.001, p = 0.001, respectively) and ring 2 in group B (p = 0.02) and delayed latency in ring 5 in groups A and B (p = 0.04 and p = 0.04, respectively). Abnormal FAF images appeared in three cases and OCT abnormalities in one case, whereas no changes were observed in controls (p = 0.55 and p = 1.00, respectively). Full-field ERG and mfERG are more sensitive tools for detecting early retinal changes in β-thalassemia patients compared with ophthalmoscopy, VEP, FAF imaging and OCT scans.

Early postoperative evaluation of retinal function by electroretinography after vitreous surgery for idiopathic epimacular membrane.

In this study, we used the PuREC to carry out electroretinography (ERG) measurements using skin electrodes to assess changes before and after microincision vitreous surgery (MIVS) for epiretinal membrane (ERM) and evaluate the stress on retinal function soon after MIVS. The study subjects were 18 eyes of 18 patients who underwent MIVS for ERM simultaneously with cataract surgery. ERG measurements were performed using a skin electrode on the day before vitreous surgery, on the day after surgery, and 1week later. The amplitude and implicit time of each waveform were measured, and the changes between preoperative results and those 1day and 1week postoperatively were investigated. Preoperatively, the dark-adapted (DA) 0.01 ERG, the DA 3.0 ERG a-wave amplitude, and the light-adapted (LA) 3.0 ERG b-wave amplitude were significantly smaller in affected eyes compared with their fellow eyes (P<0.05, Wilcoxon's signed-rank test). The day after surgery, all-wave amplitude showed no significant difference compared to preoperatively (repeated-measures analysis of variance (ANOVA) post hoc test). One week after surgery, the LA 3.0 ERG for b-waves and flicker ERG amplitude had improved from the value on the day after surgery (P<0.05, ANOVA post hoc test). Cone ERG components have improved within 1week after surgery by MIVS for ERM.

EVALUATION OF SHORT-TERM OUTCOMES OF INTRAVITREAL AFLIBERCEPT INJECTIONS FOR AGE-RELATED MACULAR DEGENERATION USING FOCAL MACULAR ELECTRORETINOGRAPHY.

To evaluate the relationship between morphological changes and functional improvements assessed using focal macular electroretinograms after intravitreal aflibercept (IVA) injections in eyes with wet age-related macular degeneration. The clinical records of 42 eyes of 42 consecutive patients with naive, wet age-related macular degeneration received 3 monthly IVA were reviewed. The best-corrected visual acuity, central foveal thickness, outer retinal thickness, inner retinal thickness at baseline and 1 month after each IVA, and focal macular electroretinograms at baseline and 1 month after the first and third IVA were compared. Best-corrected visual acuity was improved after the third IVA (P = 0.0091). Central foveal thickness and outer retinal thickness showed decreases after every IVA (P < 0.001, respectively). Inner retinal thickness showed a decrease after the second IVA (P = 0.002), after and third IVA (P = 0.001). On focal macular electroretinograms, a- and b-wave amplitudes showed increases after the third IVA (P = 0.0028, P = 0.0012, respectively). Significant correlations were observed between best-corrected visual acuity and central foveal thickness, a-wave amplitude and outer retinal thickness, and b-wave amplitude and inner retinal thickness changes after the third IVA. All parameters significantly recovered after three monthly IVA, with a correlation between functional improvements and morphological changes.

Comparing three different modes of electroretinography in experimental glaucoma: diagnostic performance and correlation to structure.

To compare diagnostic performance and structure-function correlations of multifocal electroretinogram (mfERG), full-field flash ERG (ff-ERG) photopic negative response (PhNR) and transient pattern-reversal ERG (PERG) in a non-human primate (NHP) model of experimental glaucoma (EG). At baseline and after induction of chronic unilateral IOP elevation, 43 NHP had alternating weekly recordings of retinal nerve fiber layer thickness (RNFLT) by spectral domain OCT (Spectralis) and retinal function by mfERG (7F slow-sequence stimulus, VERIS), ff-ERG (red 0.42 log cd-s/m2 flashes on blue 30 scotopic cd/m2 background, LKC UTAS-E3000), and PERG (0.8° checks, 99% contrast, 100cd/m2 mean, 5reversals/s, VERIS). All NHP were followed at least until HRT-confirmed optic nerve head posterior deformation, most to later stages. mfERG responses were filtered into low- and high-frequency components (LFC, HFC, >75Hz). Peak-to-trough amplitudes of LFC features (N1, P1, N2) and HFC RMS amplitudes were measured and ratios calculated for HFC:P1 and N2:P1. ff-ERG parameters included A-wave (at 10ms), B-wave (trough-to-peak) and PhNR (baseline-to-trough) amplitudes as well as PhNR:B-wave ratio. PERG parameters included P50 and N95 amplitudes as well as N95:P50 ratio and N95 slope. Diagnostic performance of retinal function parameters was compared using the area under the receiver operating characteristic curve (A-ROC) to discriminate between EG and control eyes. Correlations to RNFLT were compared using Steiger's test. Study duration was 15±8months. At final follow-up, structural damage in EG eyes measured by RNFLT ranged from 9% above baseline (BL) to 58% below BL; 29/43 EG eyes (67%) and 0/43 of the fellow control eyes exhibited significant (>7%) loss of RNFLT from BL. Using raw parameter values, the largest A-ROC findings for mfERG were: HFC (0.82) and HFC:P1 (0.90); for ff-ERG: PhNR (0.90) and PhNR:B-wave (0.88) and for PERG: P50 (0.64) and N95 (0.61). A-ROC increased when data were expressed as % change from BL, but the pattern of results persisted. At 95% specificity, the diagnostic sensitivity of mfERG HFC:P1 ratio was best, followed by PhNR and PERG. The correlation to RNFLT was stronger for mfERG HFC (R=0.65) than for PhNR (R=0.59) or PERG N95 (R=0.36), (p=0.20, p=0.0006, respectively). The PhNR flagged a few EG eyes at the final time point that had not been flagged by mfERG HFC or PERG. Diagnostic performance and structure-function correlation were strongest for mfERG HFC as compared with ff-ERG PhNR or PERG in NHP EG.

Retinal A2A and A3 adenosine receptors modulate the components of the rat electroretinogram.

Adenosine is a neuromodulator present in various areas of the central nervous system, including the retina. Adenosine may serve a neuroprotective role in the retina, based on electroretinogram (ERG) recordings from the rat retina. Our purpose was to assess the role of A2A and A3 adenosine receptors in the generation and modulation of the rat ERG. The flash ERG was recorded with corneal electrodes from Sprague Dawley rats. Agonists and antagonists for A2A and A3 receptors, and adenosine were injected (5 µl) into the vitreous. The effects on the components of the single flash scotopic and photopic ERGs were examined, and ERG flicker. Adenosine (0.5 mM) increased the mean amplitudes of the scotopic ERG a-waves (68 ± 8 to 97 ± 14 µV, P = 0.042), and b-waves (236 ± 38 µV to 305 ± 42 µV). A2A agonist CGS21680 (2 mM) reduced the mean amplitude of the ERG b-wave, from 298 ± 21 µV in response to the brightest stimulus to 212 ± 19 µV (P = 0.005), and mean scotopic oscillatory potentials (OPs) from 100 ± 9 µV to 47 ± 11 µV (P = 0.023). ZM241385 [4 mM], an A2A antagonist, decreased the scotopic b-wave of the ERG. A3 agonist 2-CI-IB-MECA (0.5 mM) increased the a-wave, while decreasing the scotopic and photopic ERG b-waves, and the scotopic OPs. A3 antagonist VUF5574 (1 mM) increased the mean amplitude of the scotopic a-wave (66 ± 8 to 140 ± 29 µV, P = 0.046) and b-wave (224 ± 20 to 312 ± 39 µV, P = 0.0037). No significant effects on ERG flicker were found. We conclude that retinal neurons containing A2A and/or A3 adenosine receptors contribute to the generation of the ERG a- and b-waves and OPs.

Association between Asymptomatic Unilateral Internal Carotid Artery Stenosis and Electrophysiological Function of the Retina and Optic Nerve.

Purpose. This study was designed to assess retinal and optic nerve bioelectrical function in patients with unilateral asymptomatic but hemodynamically significant internal carotid artery stenosis (ICAS). Methods. Forty-two subjects with a diagnosis of unilateral ICAS and 34 controls were analyzed. Full-field electroretinogram (ERG), pattern electroretinogram (PERG), and pattern visual-evoked potentials, as well as optical coherence tomography and ophthalmological examination, were performed. Data analysis included eyes ipsilateral to ICAS (EIS) and eyes contralateral to ICAS (ECS). Results. Intraocular pressure was significantly decreased in EIS and ECS compared to that in the controls. In the macula, both the cube average thickness and cube volume values were significantly reduced both in EIS and ECS compared to those in the controls. Similarly, PERG P50 and N95 wave amplitudes were significantly smaller in EIS and ECS compared to those in the controls. The ERG rod b-wave and rod-cone a-wave amplitudes were decreased, and implicit times were significantly prolonged, whereas the OP wave index was reduced in EIS compared to that in the controls. No differences in IOP, OCT, or ERG and PERG parameters were identified between EIS and ECS. Conclusions. Our study demonstrated that retinal bioelectrical function is negatively affected by ICAS despite the absence of objective clinical signs and symptoms of ocular ischemia.

Grafted c-kit+/SSEA1- eye-wall progenitor cells delay retinal degeneration in mice by regulating neural plasticity and forming new graft-to-host synapses.

BackgroundDespite diverse pathogenesis, the common pathological change observed in age-related macular degeneration and in most hereditary retinal degeneration (RD) diseases is photoreceptor loss. Photoreceptor replacement by cell transplantation may be a feasible treatment for RD. The major obstacles to clinical translation of stem cell-based cell therapy in RD remain the difficulty of obtaining sufficient quantities of appropriate and safe donor cells and the poor integration of grafted stem cell-derived photoreceptors into the remaining retinal circuitry.MethodsEye-wall c-kit+/stage-specific embryonic antigen 1 (SSEA1)− cells were isolated via fluorescence-activated cell sorting, and their self-renewal and differentiation potential were detected by immunochemistry and flow cytometry in vitro. After labeling with quantum nanocrystal dots and transplantation into the subretinal space of rd1 RD mice, differentiation and synapse formation by daughter cells of the eye-wall c-kit+/SSEA1− cells were evaluated by immunochemistry and western blotting. Morphological changes of the inner retina of rd1 mice after cell transplantation were demonstrated by immunochemistry. Retinal function of rd1 mice that received cell grafts was tested via flash electroretinograms and the light/dark transition test.ResultsEye-wall c-kit+/SSEA1− cells were self-renewing and clonogenic, and they retained their proliferative potential through more than 20 passages. Additionally, eye-wall c-kit+/SSEA1− cells were capable of differentiating into multiple retinal cell types including photoreceptors, bipolar cells, horizontal cells, amacrine cells, Müller cells, and retinal pigment epithelium cells and of transdifferentiating into smooth muscle cells and endothelial cells in vitro. The levels of synaptophysin and postsynaptic density-95 in the retinas of eye-wall c-kit+/SSEA1− cell-transplanted rd1 mice were significantly increased at 4 weeks post transplantation. The c-kit+/SSEA1− cells were capable of differentiating into functional photoreceptors that formed new synaptic connections with recipient retinas in rd1 mice. Transplantation also partially corrected the abnormalities of inner retina of rd1 mice. At 4 and 8 weeks post transplantation, the rd1 mice that received c-kit+/SSEA1− cells showed significant increases in a-wave and b-wave amplitude and the percentage of time spent in the dark area.ConclusionsGrafted c-kit+/SSEA1− cells restored the retinal function of rd1 mice via regulating neural plasticity and forming new graft-to-host synapses.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0451-8) contains supplementary material, which is available to authorized users.

The Effect on Retinal Structure and Function of 15 Specific ABCA4 Mutations: A Detailed Examination of 82 Hemizygous Patients.

To determine the effect of 15 individual ABCA4 mutations on disease severity. Eighty-two patients harboring 15 distinct ABCA4 mutations in trans with null (hemizygous), 10 homozygous, and 20 nullizygous patients were recruited. Age of onset was determined from medical histories. Electroretinography (ERG) responses were classified into three groups (normal; cone dysfunction; cone and rod dysfunction). The dark-adapted bright-flash (DA 10.0) a-wave amplitudes and the light-adapted flicker ERG (LA 3.0 30 Hz) amplitudes were plotted against age and compared with the nullizygous patients. Fundus autofluorescence imaging (FAF) was assessed when available. Patients hemizygous for p.G1961E and p.R2030Q had normal ERGs. Patients harboring p.R24H, p.R212C, p.G863A/delG, p.R1108C, p.P1380L, p.L2027F, and c.5714+5G>A had abnormal ERGs (ERG group 2 or 3) at older ages, in most cases with significantly higher amplitudes than nullizygous patients. Mutations p.L541P+A1038V, p.E1022K, p.C1490Y, p.E1087K, p.T1526M, and p.C2150Y were associated with abnormal ERGs (group 2 or 3) and amplitudes comparable to those of nullizygous patients. The majority of patients, including those harboring p.G1961E, had foveal atrophy; while both patients harboring p.R2030Q had foveal sparing. Most patients harboring intermediate and null-like mutations displayed FAF abnormalities extending beyond the vascular arcades. In the hemizygous state, 2/15 ABCA4 alleles retain preserved peripheral retinal function; 7/15 are associated with either preserved or only mildly abnormal retinal function, worse in older patients; 6/15 behave like null mutations. These data help characterize the degree of dysfunction conferred by specific mutant ABCA4 proteins in the human retina.