Flicker Electroretinography Research Articles

Intravitreal Injection of 1.25% Povidone Iodine Followed by Vitrectomy Using 0.025% Povidone Iodine Irrigation for Treating Endophthalmitis.

PurposeTo investigate the safety and effectiveness of intravitreal injection (IVI) of 1.25% povidone iodine (PI) followed by vitrectomy using 0.025% PI irrigation for treating endophthalmitis.MethodsProspective case series study. Nine eyes of 8 patients with postoperative or endogenous endophthalmitis treated at the Nihon University Hospital between April 2015 and October 2017 were studied. First, IVI of 0.1 mL/1.25%PI was conducted, followed by anterior chamber irrigation and vitrectomy using 0.025%PI irrigation solution. Corneal epithelial damage, anterior chamber inflammation, and vitreous inflammation were assessed and fundus examinations were performed, using a slit-lamp microscope and indirect ophthalmoscopy. A specular microscope, Goldmann perimetry, and electroretinography (ERG) were also used.ResultsIn all but case 7, endophthalmitis resolved rapidly and good visual acuity was maintained. No adverse events were noted. Furthermore, the perioperative ERG showed improvements in the oscillatory potentials amplitudes on ERG and flicker ERG, as well as in the implicit time of the a-wave, suggesting functional recovery in the retinal outer and inner layers after therapy.ConclusionsIVI of PI followed by vitrectomy was thought to be a safe and effective treatment for endophthalmitis.Translational RelevanceWe succeeded in proving the clinical safety of IVI of PI followed by vitrectomy with PI irrigation as well as previous experimental reports. PI is available in world widely, therefore this method will be optimal treatment for endophthalmitis.

Early retinal neurovascular impairment in patients with diabetes without clinically detectable retinopathy

AimsTo investigate the function and the corresponding neurovascular structures in patients with diabetes without clinically detectable retinopathy.Methods Sixty-six patients with type 2 diabetes without retinopathy (NDR) and 62 healthy controls...

Electroretinographic findings in day-blind dogs.

Cone degeneration (cd; day blindness) is one of the inherited retinal diseases of dogs. Its diagnosis is based on vision testing, fundoscopy, electroretinography (ERG) and, for some breeds, on genetic tests. Typical signs of the disease are day blindness and cone dysfunction during ERG while fundoscopy does not show any abnormalities. The aim of this study was to compare behavioural findings, fundoscopic lesions and electroretinographic alterations in 12 cd-affected dogs (Alaskan Malamute, Labrador Retriever, German Shepherd, Dachshund, Yorkshire Terrier, Shih Tzu, Siberian Husky and crossbreeds) examined at our clinic. None of the examined dogs had any fundoscopic lesions, and all of them had normal scotopic vision with strongly impaired or absent photopic vision. Light-adapted transient, cone-mediated and steady-state, 31-Hz cone flicker ERGs were much below the 5th percentile limits of normality or even unrecordable, while the rod-driven ERGs were within normal values. Vision test and ERG results corresponded to each other and, combined with the results of fundoscopy, were typical of cd. To date, our research is one of the few studies in the world presenting ERG alterations compared with vision test findings and fundoscopic results in the course of cd.

Reduction of Rod and Cone Function in 6.5-Year-Old Children Born Extremely Preterm

ImportanceThe function of rods and cones in children born extremely preterm has not yet been fully investigated.ObjectiveTo compare retinal function via full-field electroretinographic (ffERG) recordings in 6.5-year-old children born extremely preterm with children born at term.Design, Setting, and ParticipantsA subcohort study was conducted from July 1, 2010, to January 15, 2014, of the national Extremely Preterm Infants in Sweden Study, including preterm children (<27 weeks’ gestational age) and children born at term, at 6.5 years of age and living in the Uppsala health care region in Sweden. Full-field electroretinography was performed binocularly, using DTL electrodes and electroretinographic (ERG) protocols with flash strengths of 0.009, 0.17, 3.0, and 12.0 candelas (cd)/s/m2, together with 30-Hz flicker and 3.0 cd/s/m2 single-cone flash.Main Outcomes and MeasuresThe ffERG recordings were analyzed, and their associations with gestational age and retinopathy of prematurity were examined.ResultsAdequate ffERG recordings were obtained from 52 preterm children (19 girls and 33 boys; mean [SD] age at examination, 6.6 [0.1] years) and 45 children born at term (22 girls and 23 boys; mean [SD] age at examination, 6.6 [0.1] years). Lower amplitudes of the combined rod and cone responses (the a-wave of the dark-adapted ERG protocol of 3.0 cd/s/m2: mean difference, –48.9 μV [95% CI, –80.0 to –17.9 μV]; P=.003; the a-wave of the dark-adapted ERG protocol of 12.0 cd/s/m2: mean difference, –55.7 μV [95% CI, –92.5 to –18.8 μV]; P = .004), as well as of the isolated cone response (30-Hz flicker ERG: mean difference, –12.1 μV [95% CI, –22.5 to –1.6 μV]; P = .03), were found in the preterm group in comparison with the group born at term. The implicit time of the combined rod and cone responses (the a-wave of the dark-adapted ERG protocol of 12.0 cd/s/m2) was longer (mean difference, 1.2 milliseconds [95% CI, 0.3-2.0 milliseconds]; P = .01) in the preterm group, as were the isolated cone responses (30-Hz flicker ERG: mean difference, 1.2 milliseconds [95% CI, 0.5-1.8 milliseconds]; P < .001), than in the group born at term. No association was found between the ffERG recordings and gestational age or retinopathy of prematurity in the preterm group.Conclusions and RelevanceBoth rod function and cone function were reduced in children born extremely preterm when compared with children born at term. There was no association with retinopathy of prematurity in the preterm group, which suggests that being born extremely preterm may be one of the main reasons for a general retinal dysfunction.

Central Retinal Vein Occlusion in Younger Swedish Adults: Case Reports and Review of the Literature.

Purpose:To investigate associated systemic diseases, other conditions, visual outcome, ocular complications and treatment in Swedish patients younger than 50 years with central retinal vein occlusion (CRVO) and reviewing the literature.Methods:Twenty-two patients with CRVO, younger than 50 years, were examined with full-field electroretinography (ERG) within 3 months after a thrombotic event, or were periodically examined and were observed for at least 6 months. In 18 of these patients, the initial retinal ischemia was studied using the cone b-wave implicit time in the 30 Hz flicker ERG. Fifteen patients also underwent fluorescein angiography. Optical coherence tomography (OCT) was performed in 14 patients. The patients studied were divided into two groups, non-ischemic and ischemic, which were compared. All patients underwent ocular and systemic examination, as well as complete screening for thrombophilic risk factors.Results:Of the 22 patients, 15 had non-ischemic type of CRVO and 7 the ischemic type. Patients with non-ischemic CRVO showed significantly improved visual acuity (VA) at the final examination (p=0.006). Patients with ischemic CRVO showed no significant reduction in VA at the final examination (p=0.225). Systemic hypertension (27% in non-ischemic CRVO and 29% in ischemic CRVO) was the most prevalent systemic risk factor for CRVO. The mean central foveal thickness (CFT) decreased significantly from 402.3±136.2 (µm) at the initial examination to 243.8±48.1 (µm) at the final examination in the non-ischemic group (p=0.005). The mean initial CFT was 444.5±186.1 (µm) in the ischemic CRVO group, which decreased to 211.5±20.2 (µm) at the final visit (p=0.068). Pigment dispersion syndrome (PDS)/pigmentary glaucoma (PG), ocular hypertension and dehydration were equally frequent; four patients each (18%) out of 22. The clinical course of 4 younger patients with PDS/PG are described.Conclusion:The patients with non-ischemic CRVO showed significantly improved VA and significantly decreased CFT at the final examination. Systemic hypertension was the most prevalent risk factor for CRVO. Younger adults with CRVO also had a high prevalence of PDS/PG, ocular hypertension and dehydration. This study highlights the importance of careful IOP monitoring, and the need to investigate possible PDS/PG and to obtain an accurate history of the patient including alcohol intake and intense exercise.

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.

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.

Differentiation of murine models of "negative ERG" by single and repetitive light stimuli.

Marked attenuation of the single-flash electroretinographic (ERG) b-wave in the presence of a normal-amplitude or less-attenuated a-wave is commonly referred to as the "negative ERG." The purpose of this study was to investigate whether the disparate origins of the negative ERG in three murine models can be discriminated using flickering stimuli. Three models were selected: (1) the Nyx (nob) mouse model of complete congenital stationary night blindness, (2) the oxygen-induced retinopathy (OIR) rat model of retinopathy of prematurity (ROP), and (3) the Rs1 knockout (KO) mouse model of X-linked juvenile retinoschisis. Directly after a dark-adapted, single-flash ERG luminance series, a flicker ERG frequency series (0.5-30 Hz) was performed at a fixed luminance of 0.5 log cd s/m(2). This series includes frequency ranges that are dominated by activity in (A) the rod pathways (below 5 Hz), (B) the cone ON-pathway (5-15 Hz), and (C) the cone OFF-pathway (above 15 Hz). All three models produced markedly attenuated single-flash ERG b-waves. In the Nyx (nob) mouse, which features postsynaptic deficits in the ON-pathways, the a-wave was normal and flicker responses were attenuated in ranges A and B, but not C. The ROP rat is characterized by inner-retinal ischemia which putatively affects both ON- and OFF-bipolar cell activity; flicker responses were reduced in all ranges (A-C). Notably, the choroid supplies the photoreceptors and is thought to be relatively intact in OIR, an idea supported by the nearly normal a-wave. Finally, in the Rs1 KO mouse, which has documented abnormality of the photoreceptor-bipolar synapse affecting both ON- and OFF-pathways, the flicker responses were attenuated in all ranges (A-C). The a-wave was also attenuated, likely as a consequence to schisms in the photoreceptor layer. Consideration of both single-flash and flickering ERG responses can discriminate the functional pathology of the negative ERG in these animal models of human disease.

Efficacy of Column Scatter Plots for Presenting Retinitis Pigmentosa Phenotypes in a Japanese Cohort.

PurposeWe evaluated the efficacy of column scatter plots to describe genotype–phenotype correlations in a Japanese cohort with retinitis pigmentosa (RP).MethodsClinical records of 121 patients with RP with identified causative mutations were reviewed. Visual acuity, central and peripheral visual fields, electroretinography (ERG), lens status, and measurements of optical coherence tomography were evaluated according to causative genes using column scatter plots. Values for three common genes (EYS, USH2A, and RHO) were compared statistically.ResultsAll patients with PDE6B, PRPH2, and RPGR mutations, those 55 years old or younger with RP1L1 and USH2A mutations, and those 45 years old or younger with EYS and RHO mutations retained visual acuity of at least 0.1. All patients with RPGR mutations showed at least −20 dB mean deviation. Goldmann perimeter measures of 4/6 patients with RHO mutations showed remaining peripheral visual fields. Dark-adapted 0.01 and 3.0 ERGs were extinguished for most genes. Half of the patients with RHO RP maintained cone responses in light-adapted 3.0 and 3.0 flicker ERG. All patients with PRPH2, those 55 years old or younger with USH2A and RP1L1, and those 45 years old or younger with PDE6B and EYS mutations maintained subfoveal ellipsoid zones. No differences were identified between EYS and USH2A or RHO and USH2A.ConclusionsColumn scatter plots enabled comparisons of the associated severities and illustration of the ophthalmological measurements for every RP causative gene.Translational RelevanceAnalysis of mutations in specific genes may be helpful for determining visual prognoses in the clinical setting.

Diet enriched with the Amazon fruit açaí (Euterpe oleracea) prevents electrophysiological deficits and oxidative stress induced by methyl-mercury in the rat retina

Background: The protective effect of a diet supplemented by the Amazonian fruit Euterpe oleracea (EO) against methylmercury (MeHg) toxicity in rat retina was studied using electroretinography (ERG) and biochemical evaluation of oxidative stress.Method: Wistar rats were submitted to conventional diet or EO-enriched diet for 28 days. After that, each group received saline solution or 5 mg/kg/day of MeHg for 7 days. Full-field single flash, flash and flicker ERGs were evaluated in the following groups: control, EO, MeHg, and EO+MeHg. The amplitudes of the a-wave, b-wave, photopic negative response from rod and/or cone were measured by ERGs as well as the amplitudes and phases of the fundamental component of the sine-wave flicker ERG. Lipid peroxidation was determined by thiobarbituric acid reactive species.Results: All ERG components had decreased amplitudes in the MeHg group when compared with controls. EO-enriched food had no effect on the non-intoxicated animals. The intoxicated animals and those that received the supplemented diet presented significant amplitude reductions of the cone b-wave and of the fundamental flicker component when compared with non-intoxicated control. The protective effect of the diet on scotopic conditions was only observed for bright flashes eliciting a mixed rod and cone response. There was a significant increase of lipid peroxidation in the retina from animals exposed to MeHg and EO-supplemented diet was able to prevent MeHg-induced oxidative stress in retinal tissue.Conclusion: These findings open up perspectives for the use of diets supplemented with EO as a protective strategy against visual damage induced by MeHg.

A novel device for accurate and efficient testing for vision-threatening diabetic retinopathy

AimsTo evaluate the performance of the RETeval device, a handheld instrument using flicker electroretinography (ERG) and pupillography on undilated subjects with diabetes, to detect vision-threatening diabetic retinopathy (VTDR). MethodsPerformance was measured using a cross-sectional, single armed, non-interventional, multi-site study with Early Treatment Diabetic Retinopathy Study 7-standard field, stereo, color fundus photography as the gold standard. The 468 subjects were randomized to a calibration phase (80%), whose ERG and pupillary waveforms were used to formulate an equation correlating with the presence of VTDR, and a validation phase (20%), used to independently validate that equation. The primary outcome was the prevalence-corrected area under the receiver operating characteristic (ROC) curve for the detection of VTDR. ResultsThe area under the ROC curve was 0.86 for VTDR. With a sensitivity of 83%, the specificity was 78% and the negative predictive value was 99%. The average testing time was 2.3min. ConclusionsWith a VTDR prevalence similar to that in the US, the RETeval device will identify about 75% of the population as not having VTDR with 99% accuracy. The device is simple to use, does not require pupil dilation, and has a short testing time.

A method for estimating intrinsic noise in electroretinographic (ERG) signals.

To develop a signal processing paradigm for extracting ERG responses to temporal sinusoidal modulation with contrasts ranging from below perceptual threshold to suprathreshold contrasts and estimate the magnitude of intrinsic noise in ERG signals at different stimulus contrasts. Photopic test stimuli were generated using a 4-primary Maxwellian view optical system. The 4-primary lights were sinusoidally temporally modulated in-phase (36 Hz; 2.5-50% Michelson contrast). The stimuli were presented in 1-s epochs separated by a 1-ms blank interval and repeated 160 times (160.160-s duration) during the recording of the continuous flicker ERG from the right eye using DTL fibre electrodes. After artefact rejection, the ERG signal was extracted using Fourier transforms in each of the 1-s epochs where a stimulus was presented. The signal processing allows for computation of the intrinsic noise distribution in addition to the signal-to-noise (SNR) ratio. We provide the initial report that the ERG intrinsic noise distribution is independent of stimulus contrast, whereas SNR decreases linearly with decreasing contrast until the noise limit at ~2.5%. The 1-ms blank intervals between epochs de-correlated the ERG signal at the line frequency (50 Hz) and thus increased the SNR of the averaged response. We confirm that response amplitude increases linearly with stimulus contrast. The phase response shows a shallow positive relationship with stimulus contrast. This new technique will enable recording of intrinsic noise in ERG signals above and below perceptual visual threshold and is suitable for measurement of continuous rod and cone ERGs across a range of temporal frequencies, and post-receptoral processing in the primary retinogeniculate pathways at low stimulus contrasts. The intrinsic noise distribution may have application as a biomarker for detecting changes in disease progression or treatment efficacy.

Photopic full-field electroretinography and optical coherence tomography in type 1 diabetic retinopathy.

PurposeThe purpose of this study was to evaluate the role of photopic full-field electroretinography (ERG) and retinal thickness measurements by spectral-domain optical coherence tomography (SD-OCT) in the assessment of disease severity in type 1 diabetic retinopathy.MethodsA population-based cohort of 151 patients with type 1 diabetes underwent a complete ophthalmic examination, including photopic full-field ERG and SD-OCT for retinal thickness measurements. Stereoscopic fundus photographs were taken according to the Early Treatment Diabetic Retinopathy Study protocol, and the classification of diabetic retinopathy was based on the International Clinical Diabetic Retinopathy Disease Severity Scale. Associations between photographically determined retinopathy level, b-wave amplitude and peak time of the photopic single-flash and 30-Hz flicker ERG, and central retinal thickness parameters were evaluated.ResultsFor all ERG measurements, the amplitude decreased and peak time increased with progression of the disease, but these associations lost statistical significance after adjusting for age and excluding laser-treated patients. Mean retinal thickness was significantly associated with the b-wave amplitude of photopic single-flash and 30-Hz flicker responses (r2 = 0.08, p = 0.006; and r2 = 0.05, p = 0.025, respectively), but revealed no association with retinopathy level.ConclusionsPhotopic full-field ERG and SD-OCT-derived retinal thickness parameters have limited clinical value in the staging of diabetic retinopathy. However, thinning of the central retina leads to significant functional impairment and may reflect an ongoing neurodegenerative process in the retinal tissue.

Early adaptive response of the retina to a pro-diabetogenic diet: Impairment of cone response and gene expression changes in high-fructose fed rats

The lack of plasticity of neurons to respond to dietary changes, such as high fat and high fructose diets, by modulating gene and protein expression has been associated with functional and behavioral impairments that can have detrimental consequences. The inhibition of high fat-induced rewiring of hypothalamic neurons induced obesity. Feeding rodents with high fructose is a recognized and widely used model to trigger obesity and metabolic syndrome. However the adaptive response of the retina to short term feeding with high fructose is poorly documented. We therefore aimed to characterize both the functional and gene expression changes in the neurosensory retina of Brown Norway rats fed during 3 and 8 days with a 60%-rich fructose diet (n = 16 per diet and per time point). Glucose, insulin, leptin, triacylglycerols, total cholesterol, HDL-cholesterol, LDL-cholesterol and fructosamine were quantified in plasma (n = 8 in each group). Functionality of the inner retina was studied using scotopic single flash electroretinography (n = 8 in each group) and the individual response of rod and cone photoreceptors was determined using 8.02 Hz Flicker electroretinography (n = 8 in each group). Analysis of gene expression in the neurosensory retina was performed by Affymetrix genechips, and confirmed by RT-qPCR (n = 6 in each group). Elevated glycemia (+13%), insulinemia (+83%), and leptinemia (+172%) was observed after 8 days of fructose feeding. The cone photoreceptor response was altered at day 8 in high fructose fed rats (Δ = 0.5 log unit of light stimulus intensity). Affymetrix analysis of gene expression highlighted significant modulation of the pathways of eIF2 signaling and endoplasmic reticulum stress, regulation of eIF4 and p70S6K signaling, as well as mTOR signaling and mitochondrial dysfunction. RT-qPCR analysis confirmed the down regulation of Crystallins, Npy, Nid1 and Optc genes after 3 days of fructose feeding, and up regulation of End2. Meanwhile, a trend towards an increased expression of αA- and αB-crystallin proteins was observed at day 8. Our results are consistent with early alterations of the functioning and gene expression in the retina in a pro diabetogenic environment.

Ocular blood flow and retinal electrogenesis in retinitis pigmentosa

to investigate correlations between changes in ocular hemodynamics revealed by color Doppler flow mapping (CDFM) and pulsed-wave (PW) Doppler imaging, one the one hand, and electrical activity of the retina, on the other, in patients with early, moderate, and severe retinitis pigmentosa (RP). A total of 20 patients (40 eyes) aged from 16 to 40 years (28.4 ± 8.2 years on average) with retinitis pigmentosa were enrolled. The control group consisted of 20 healthy volunteers of the same age range. All participants underwent full-field electroretinography (ERG), flicker ERG, and macular ERG as well as blood flow assessment in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCA) by means of CDFM and PW-Doppler. Ocular blood flow in CRA and SPCA appeared disturbed in patients with early RP. In cases of moderate and severe RP, the peak systolic velocity of CRA and SPCA blood flow was significantly decreased. Systolic and end diastolic blood flow velocities in CRA and SPCA has been shown to be directly related to full-field ERG a-wave and b-wave amplitudes, correspondingly, but negatively correlated with their implicit times. The revealed decrease in CRA and SPCA blood flow indices proves retinal and choroidal circulation deficit in patients with advanced RP. As shown, moderate blood flow changes are already present in early RP and progress as retinal photoreceptors and bipolar cells become suppressed, which may be useful for RP diagnosis and monitoring.

Human flicker electroretinography using different temporal modulations at mesopic and photopic luminance levels.

Electroretinographic measurement instruments allow the variation of several stimulation parameters enabling to study a wide range of retinal processes. The purpose of the present study was to measure human flicker electroretinograms (ERGs) varying temporal modulation, temporal frequency and mean luminance in the photopic and higher mesopic ranges where the change from cone to rod dominance occurs. Fourteen healthy subjects (mean age = 31 ± 6) participated in this study. ERG recordings were performed with the RetiPort system (Roland Consult, Germany). The stimuli were ON and OFF sawtooth waves, square wave and sine wave. The temporal frequencies were 4 and 8 Hz. The mean luminance varied from 1 to 60 cd/m(2). The results confirmed the possibility to distinguish between rod- and cone-dominated retinal responses when using the flicker ERG at different temporal frequencies and luminances. We have also evaluated the responses at luminance levels at which the transition between rod- and cone-dominated responses occurs. This transition between rod- and cone-dominated flicker ERG responses is indicated by a significant change in the response characteristics between 4 and 8 cd/m(2) (between 200 and 400 phot Td). The findings on the transition between rod- and cone-dominated ERGs along with the demonstration of ERG responses to different temporal flicker modulations might be informative for the electrophysiologists when setting up the stimulus at mesopic and photopic luminance levels.

Wide-field fundus autofluorescence abnormalities and visual function in patients with cone and cone-rod dystrophies.

To evaluate the clinical utility of wide-field fundus autofluorescence (FAF) in patients with cone dystrophy and cone-rod dystrophy. Sixteen patients with cone dystrophy (CD) and 41 patients with cone-rod dystrophy (CRD) were recruited at one institution. The right eye of each patient was included for analysis. We obtained wide-field FAF images using a ultra-widefield retinal imaging device and measured the area of abnormal FAF. The association between the area of abnormal FAF and the results of visual acuity measurements, kinetic perimetry, and electroretinography (ERG) were investigated. The mean age of the participants was 51.4 ± 17.4 years, and the mean logarithm of the minimum angle of resolution was 1.00 ± 0.57. The area of abnormal FAF correlated with the scotoma measured by the Goldman perimetry I/4e isopter (ρ = 0.79, P < 0.001). The area also correlated with amplitudes of the rod ERG (ρ = -0.63, P < 0.001), combined ERG a-wave (ρ = -0.72, P < 0.001), combined ERG b-wave (ρ = -0.66, P < 0.001), cone ERG (ρ = -0.44, P = 0.001), and flicker ERG (ρ = -0.47, P < 0.001). The extent of abnormal FAF reflects the severity of functional impairment in patients with cone-dominant retinal dystrophies. Fundus autofluorescence measurements are useful for predicting retinal function in these patients.

Electroretinogram evaluation of equine eyes with extensive 'bullet-hole' fundic lesions.

To evaluate the impact of extensive bullet-hole nontapetal fundic lesions in horses on retinal function as measured by full-field electroretinography (ERG). Full-field ERG was performed on two horses with numerous bullet-hole lesions in the nontapetal fundus of both eyes. The ERG was first recorded from the eye with the more extensive lesions in response to a low-intensity light stimulus (0.03 cd s/m(2) ) that was given at times (T) T = 5, 10, 15, 20 min of dark adaptation. Consecutively, combined rod-cone response was evaluated bilaterally in response to high-intensity light stimulus (3 cd s/m(2) ), followed by cone function evaluation by flicker stimulus (3 cd s/m(2) at 30 Hz). Off-line analysis of the ERG recordings was then performed. Despite extensive bullet-hole lesions in the nontapetal fundus bilaterally in both horses, retinal function as measured by ERG did not show any observable deficits. The b-wave amplitude of the full-field ERG increased continuously from 5 to 20 min of dark adaptation peaking at 446 μv and 377 μv for horse number 1 and 2, respectively. The b-wave amplitudes of the combined rod-cone response were OS- 459 μv and OD- 392 μv for horse number 1 and OS- 491 μv and OD- 608 μv for horse number 2. The amplitude of the flicker ERG for horse number 1 was OS- 86 μv and OD- 110 μv and for horse number 2, OS- 80 μv and OD- 74 μv. Extensive bullet-hole chorioretinal lesions do not appear to compromise outer retinal function in these horses.

A Phenotype–Genotype Correlation Study of X-Linked Retinoschisis

To compare the clinical phenotype and detailed electroretinographic parameters in X-linked retinoschisis (XLRS). Retrospective, comparative study. Fifty-seven patients (aged 1-67 years) with molecularly confirmed XLRS were clinically ascertained. Pattern electroretinography (PERG) and full-field electroretinography (ERG), incorporating international standard recordings, were performed in 44 cases. Thirteen patients, mostly pediatric, were tested using a simplified ERG protocol. On-Off and S-cone ERGs were performed in most adults. Fundus autofluorescence (FAF) imaging and optical coherence tomography (OCT) were available in 17 and 21 cases, respectively. The clinical and electrophysiologic data associated with different types of mutation in the RS1 gene. Forty-three patients had missense changes (group A), and 14 patients had nonsense, splice-site, or frame-shifting mutations in the RS1 gene (group B). The mean best-corrected visual acuity was better in group A than in group B (0.34 and 0.21, respectively). Fundus examination revealed foveal schisis in approximately half of both groups. The bright-flash dark-adapted (DA) ERG (11.0 candela.sec.m(-2)) waveform was electronegative in 62% of group A eyes and 100% of group B eyes. The photopic 30-Hz flicker ERG was delayed in all group B eyes and all except 6 group A eyes. On-Off ERG b-waves were subnormal in 39% of group A and 89% of group B eyes; d-waves were delayed in 14 eyes (group A = 10, group B = 4). S-cone ERGs were abnormal in 50% of both groups. The PERG was abnormal in 88% of group A and 100% of group B eyes. A spoke-wheel pattern of high and low intensity was the most common FAF abnormality observed. The OCT showed intraretinal schitic cavities in the majority of eyes. There is profound phenotypic variability in patients with XLRS. Most patients have DA bright-flash ERGs with a low b:a ratio in keeping with inner retinal dysfunction. Generalized cone system dysfunction is common and associated with an abnormal On-response and less frequent additional Off-response involvement. Nonsense, splice-site, or frame-shifting mutations in RS1 consistently caused electronegative bright-flash ERG, delayed flicker response, and abnormal PERG; missense mutations result in a wider range of ERG abnormalities.

Retinal On-Pathway Deficit in Congenital Disorder of Glycosylation Due to Phosphomannomutase Deficiency

To describe novel electroretinographic (ERG) findings associated with congenital disorder of glycosylation due to phosphomannomutase deficiency (PMM2-CDG) (previously known as congenital disorder of glycosylation type 1a). Two male siblings with genetically confirmed PMM2-CDG underwent full-field ERG to a range of scotopic and photopic flash luminances that extended the International Society for Clinical Electrophysiology of Vision standard protocol and included scotopic 15-Hz flicker and photopic prolonged on-off stimulation. Photopic prolonged ERGs were profoundly electronegative with absent b-waves but preserved oscillatory potentials. Prolonged off-responses and off-oscillatory potentials were preserved. Transient full-field photopic ERGs revealed a broad a-wave and narrow b-wave, and the photopic 30-Hz flicker ERG had a sawtooth waveform. The scotopic b-waves of both cases were attenuated to the fifth percentile, whereas scotopic a-wave amplitudes were at the 50th to 75th percentile, giving a reduced a:b ratio. The scotopic a-wave waveform was well defined to bright flash luminance. The number of scotopic oscillatory potentials was preserved, although amplitudes were smaller than average. Scotopic 15-Hz flicker ERGs were evident to a range of flash luminances and showed an expected phase cancellation between -1.5 and -1.0 log scotopic td (troland) • s, but phase increased only for the fast rod pathway. We find, for the first time to our knowledge, an association of PMM2-CDG with a selective on-pathway dysfunction in the retina. This ERG phenotype localizes the site of retinal dysfunction to the on-bipolar synapse with photoreceptors. Modeling the unusual combination of ERG findings helps our understanding of the role of N -glycosylation at this synapse and provides a focus for future studies of potential intervention.