Assessment of the uniform field electroretinogram for mouse retinal ganglion cell functional analysis.

PURPOSE: The uniform field electroretinogram (UF-ERG) has been suggested as an alternative to the pattern electroretinogram (PERG) for non-invasive assessment of retinal ganglion cell (RGC) function in primates. We evaluated the validity of the UF-ERG to assess mouse RGC activity in vivo. METHODS: Unilateral optic nerve crush (ONC) was performed on adult C57BL/6J mice. Contralateral eyes with uncrushed optic nerves and eyes from surgically naive mice served as experimental controls. Electrophysiological visual assessment was performed at 12 weeks post-ONC. Flash-mediated visual-evoked cortical potentials (VEPs) were measured to confirm the robustness of the ONC procedure. Full-field flash ERGs were used to interrogate photoreceptor and retinal bipolar cell function. RGC function was assessed with pattern ERGs. Summed onset and offset UF-ERG responses to alternating dark and light uniform field flash stimuli of different intensities and wavelengths were recorded from ONC and control eyes, and relative differences were compared to the PERG results. Following electrophysiological analysis, RGC loss was monitored by immunohistochemical staining of the RGC marker protein, RBPMS, in post-mortem retinal tissues. RESULTS: ONC dramatically impacts RGC integrity and optic nerve function, demonstrated by reduced RGC counts and near complete elimination of VEPs. ONC did not affect scotopic ERG a-wave and b-wave amplitudes, while PERG amplitudes of eyes subjected to ONC were reduced by approximately 50% compared to controls. Summation of ON and OFF UF-ERG responses did not reveal statistically significant differences between ONC and control eyes, regardless of visual stimulus. CONCLUSIONS: PERG responses are markedly impaired upon ONC, while UF-ERG responses are not significantly affected by surgical trauma to RGC axons in mice. The more closely related pattern and uniform field ERGs recorded in primates suggests species-specific differences in RGC features or subpopulations corresponding to PERG and UF-ERG response generators, limiting the utility of the UF-ERG for mouse RGC functional analysis.

Assessment of factors affecting flicker ERGs recorded with RETeval from data obtained from health checkup screening.

PURPOSE: To determine the factors significantly associated with the amplitudes and implicit times of the flicker electroretinograms (ERGs) recorded with the RETeval system by analyzing the comprehensive data obtained during a health checkup screening. METHODS: Flicker ERGs were recorded with the RETeval system from 373 individuals who had a normal fundus and optical coherence tomography images. The sex, age, anthropometric, ophthalmologic, and hematologic data were collected from all participants who were 40- to 89-years-of-age. Univariable and multivariable linear mixed effects regression analyses were performed to identify factors that were significantly associated with the implicit times and amplitudes of the RETeval flicker ERGs. RESULTS: Univariable linear mixed effects regression analysis showed significant correlations between the implicit times and the best-corrected visual acuity, the age, the axial length, the blood sugar level, and the blood urea nitrogen level. Analyses by multivariable linear mixed effects regression identified that the axial length (ß = 0.28), the age (ß = 0.24), and the blood sugar level (ß = 0.092) were three independent factors that were significantly correlated with the implicit times of the RETeval flicker ERGs. Univariable linear mixed effects regression analysis also showed significant correlations between the amplitudes of the RETeval flicker ERGs and the age, the platelet count, and the creatinine level. Multivariable linear mixed effects regression models identified the age (ß = -0.092), the platelet count (ß = 0.099), and the creatinine level (ß = -0.12) as three independent factors that were significantly correlated with the amplitudes of the RETeval flicker ERGs. However, the smoking habits, body mass index, and the blood pressure were not significantly correlated with either the implicit times or amplitudes of the RETeval flicker ERGs. CONCLUSIONS: Our results indicate that the age and some ophthalmologic and hematologic findings but not the anthropometric findings were significantly associated with the implicit times and amplitudes of the RETeval flicker ERGs. Thus, clinicians should remember these factors when analyzing the RETeval flicker ERGs.

[Multifocal electroretinography in assessment of the functional state of the central retina in patients with retinitis pigmentosa]. / Mul'tifokal'naya elektroretinografiya v otsenke funktsional'nogo sostoyaniya tsentral'noi zony setchatki pri pigmentnom retinite.

Retinitis pigmentosa (RP) is an inherited disease associated with various genetic mutations. Developments in the field of genetic engineering give relevance to the search for methods of studying retinal function, which can prove informative in the selection of patients for treatment. PURPOSE: To evaluate the information content of multifocal electroretinography (mfERG) in the diagnostics of the functional state of the central retina in retinitis pigmentosa (RP). MATERIAL AND METHODS: The study included 115 patients (228 eyes) with PR and 15 people (30 eyes) who comprised the control group. All subjects underwent standard ophthalmological examination, computer perimetry, color vision study, retinal spectral optical coherence tomography, ganzfeld electroretinography (gERG) and mfERG. The relationship between mfERG parameters and the degree of gERG changes, as well as various functional and morphological parameters of the retina was assessed. RESULTS: Visual acuity and perimetry indices varied over a wide range. GERG was unrecordable in 50.4% of cases. MfERG was registered in 214 (98.3%) eyes with varying degrees of change in visual acuity, visual field and gERG parameters. A medium degree positive relationship was revealed between the biopotential density of the retina in the foveal and parafoveal zones and visual acuity (rs=0.68; 0.63), a high degree - between the density of ttotal biopotential of the central retina (DValue) and the average light sensitivity (rs=0.9), a weak degree - between DValue and the thickness and volume of the peripheral retina (rs=0.37; 0.42), a medium negative correlation was found between the average defect in light sensitivity and the biopotential density in the periphery (Rings 4-5) on mfERG, DValue (rs= -0.67; -0.65; -0.69). CONCLUSION: MfERG detects retinal dysfunctions at an early stage of RP, in eyes with high visual acuity, normal parameters of the central visual field and gERG, as well as in low visual acuity, a pronounced decrease in light sensitivity, unrecordable gERG. MfERG can be informative in the selection of patients with RP for gene therapy.

Electrophysiological Assessment in Birdshot Chorioretinopathy: Flicker Electroretinograms Recorded With a Handheld Device.

Purpose: The flicker electroretinogram (ERG) is a sensitive indicator of retinal dysfunction in birdshot chorioretinopathy (BCR). We explored recordings from a handheld device in BCR, comparing these with conventional recordings in the same patients and with handheld ERGs from healthy individuals. Methods: Non-mydriatic flicker ERGs, using the handheld RETeval system (LKC Technologies), were recorded with skin electrodes at two centers. At one center (group 1), the stimuli (85 Td·s, 850 Td background) delivered retinal illuminance equivalent to international standards; at the other center (group 2), a different protocol was used (32 Td·s, no background). Patients also underwent international standard flicker ERG recordings with conventional electrodes following mydriasis. Portable ERGs from patients were also compared with those from healthy individuals. Results: Thirty-two patients with BCR (mean age ± SD, 56.4 ± 11.3 years) underwent recordings. Portable and standard ERG parameters correlated strongly (r > 0.75, P < 0.01) in both groups. Limits of agreement for peak times were tighter in group 1 (n = 21; -4.3 to +2.0 ms [right eyes], -3.9 to 1.5 ms [left eyes]) than in group 2 (n = 11; -3.4 to +6.9 ms [right eyes], -4.8 to +9.0 ms [left eyes]). Compared with healthy controls (n = 66 and n = 90 for groups 1 and 2, respectively), patients with BCR showed smaller mean amplitudes and longer peak times. Conclusions: Portable ERGs correlated strongly with conventional recordings, suggesting potential in rapid assessment of cone system function in office settings. Translational Relevance: Flicker ERGs, known to be useful in BCR, can be obtained rapidly with a portable device with skin electrodes and natural pupils.

[Electrophysiological and psychophysical studies in assessment of visual functions in patients with hereditary optic neuropathy]. / Elektrofiziologicheskie i psikhofizicheskie issledovaniya v otsenke zritel'nykh funktsii pri nasledstvennoi opticheskoi neiropatii.

PURPOSE: To study the capabilities of electrophysiological and psychophysical examination methods for assessment of the functional state of ganglion cells, retina and optic nerve in patients with hereditary optic neuropathy (HON). MATERIAL AND METHODS: The study included 60 patients (118 eyes) with a genetically confirmed diagnosis of HON. All study patients underwent visual field test (VFT), spectral optical coherence tomography (OCT), flash and pattern visual evoked potentials (VEP) (Flash-VEP, FVEP; Pattern-VEP, PVEP), photopic electroretinography with photonegative response (PhNR) registration and the color vision test. In 24 patients (46 eyes), these parameters were assessed before the start of treatment and one year later. The treatment involved the mitochondria-targeted antioxidant SkQ1 - plastoquinonyl-decyl-triphenylphosphonium bromide (PDTP) in the form of eye drops. RESULTS: The main PVEP components for 1.0° and 0.3° were registered in 20% and in 14% of patient eyes with HON and high visual functions, respectively. After one year of PDTP use, a significant decrease in P100 peak latency was found only in the group with disease duration of ≤1.5 years as of the time of treatment start (p<0.05). Significant differences were observed in the PhNR amplitude (p<0.004) between patients of the main and the control groups, as well as in the PhNR amplitude between patients with visual acuity of ≤0.1 and ≥0.13 (p<0.01). Patients with high visual functions were found to have a correlation between the PhNR amplitude, GCC thickness and the global loss index (GLV). CONCLUSION: Along with VFT, OCT and color vision tests, electrophysiological studies are one of the main methods of examining patients with HON. After one year of PDTP use, there was a significant decrease in the FVEP P2 peak latency in the group with a disease duration of ≤1.5 years as of the time of treatment start. The PhNR amplitude in patients with high visual functions was found to correlate with structural changes in the ganglion cell layer and the retinal nerve fiber layer.

Quantitative assessment of visual pathway function in blind retinitis pigmentosa patients.

OBJECTIVE: The current methods used to assess visual function in blind retinitis pigmentosa (RP) patients are mostly subjective. We aimed to identify effective, objective methods. METHODS: We enrolled patients diagnosed with blindness associated with RP; we finally selected 26 patients (51 eyes) with a visual field radius less than 10 degrees and divided them into the following 4 groups by best-corrected visual acuity (BCVA): group 1, no light perception (NLP, 4 eyes); group 2, light perception (LP, 12 eyes); group 3, hand movement or finger counting (faint form perception, FFP, 22 eyes); and group 4, BCVA from 0.1 to 0.8 (form perception, FP, 13 eyes). All patients underwent optometry, optical coherence tomography (OCT), color fundus photography, fundus autofluorescence (FAF), full field electroretinography (ffERG), pattern electroretinography (PERG), multifocal electroretinography (mf-ERG), pattern visual evoked potential (PVEP), flash visual evoked potential (FVEP), and pupillary light response (PLR) assessments. Five patients in groups 1, 2, and 3 (1, 2, and 2 subjects, respectively) underwent functional magnetic resonance imaging (fMRI) scans and were compared with five healthy subjects. RESULTS: The outer plexiform layer was thinner in group 1, and the outer nuclear layer was thinner in groups 1 and 2. The ffERG, PERG, and mf-ERG findings were unrecordable in all four groups. The P2 amplitude of the FVEP was significantly lower in groups 1 and 2, while the P100 amplitude of the PVEP was higher in groups 2, 3 and 4 than in group 1. After white- and blue-light stimuli, the PLR thresholds in the patients without form perception were significantly higher. The threshold of the PLR stimulated by blue and white light was negatively correlated with the amplitudes of P2 and P100. Moreover, the fMRI findings showed that some RP patients have significant visual cortex activation in response to certain types of stimulation. However, statistical analysis was not performed because of the small number of cases. CONCLUSIONS: OCT, VEP, PLR and fMRI assessments can evaluate residual visual pathway function in blind RP patients. SIGNIFICANCE: Our study may have clinical significance for the potential prediction of RP patient prognoses and the effects after clinical trials.

Electroretinographic Assessment in Joubert Syndrome: A Suggested Objective Method to Evaluate the Effectiveness of Future Targeted Treatment.

INTRODUCTION: Joubert syndrome (JS) is an autosomal recessive disorder characterized by a congenital malformation of the mid-hindbrain and a large spectrum of clinical features including congenital retinal dystrophy. The function of different retinal elements (rod, cone, bipolar cells) can be objectively evaluated by electroretinogram (ERG) recordings. Our work aims to evaluate the retinal function (by ERG recordings) in patients with JS with or without congenital retinal dystrophy. In addition, since clinical trials should be performed in the near future in JS, our results could provide information about the possible usefulness of ERG recordings in the assessment of the efficacy of treatments targeted to improve the retinal involvement. METHODS: In this observational and prospective study, 24 children with genetic identification for JS (mean age 10.75 ± 6.59 years) and 25 healthy age-similar normal control subjects (control group, mean age 10.55 ± 3.76 years) were enrolled. On the basis of the presence/absence of retinal dystrophy at fundus examination, patients with JS were divided into two groups: patients with JS with retinal dystrophy (16 children, mean age 11.00 ± 6.74 years, providing 16 eyes; JS-RD group) and patients with JS without retinal dystrophy (8 children, mean age 10.50 ± 6.45 years, providing 8 eyes; JS-NRD group). In patients with JS and controls, visual acuity (VA), dark-adapted, light-adapted, and 30-Hz flicker ERGs were performed according to International Society for Clinical Electrophysiology of Vision (ISCEV) standard protocols. RESULTS: When compared to controls, patients in the JS-RD and JS-NRD groups showed significant abnormalities of the values of dark-adapted, light-adapted, and 30-Hz flicker ERG parameters. The ERG and VA changes were not significantly correlated. CONCLUSIONS: Our results suggest that a dysfunction of photoreceptors and bipolar cells occurs in patients with JS with or without retinal dystrophy. The retinal impairment can be detected by ERG recordings and this method should be proposed to evaluate the effectiveness of adequate treatment targeted to improve the retinal impairment in patients with JS.

A novel method for electroretinogram assessment in patients with central retinal vein occlusion.

PURPOSE: Central retinal vein occlusion (CRVO) is the second most common retinal vascular disorder after diabetic retinopathy that affects the eyes. We propose a method for distinction of normal and central CRVO eyes based on electroretinogram (ERG). METHODS: Seventeen patients with CRVO in one eye were analyzed. Their ERG signals were collected in six different stimuli, including four records in the darkness (dark-adapted 0.01, dark-adapted 3.0, dark-adapted oscillatory potentials, and dark-adapted 10) and two records in brightness (light-adapted 3.0 and light-adapted 30 Hz flicker). Nonlinear features such as Hurst exponent (HE) and approximate entropy (ApEn) were extracted from healthy and CRVO eyes. Finally, a parabolic mapping and two criteria (theta angle and the density of points) were proposed to distinguish the groups. RESULTS: For ApEn, the P values of dark-adapted 3.0 oscillatory (P = 0.0433) and flicker (P = 0.0425) confirmed significant differences between the groups. For HE, the P values of dark-adapted 3.0 oscillatory (P = 0.0421) and flicker 30 Hz (P = 0.0402) confirmed differences between the healthy and CRVO groups. The P values of theta angle for dark-adapted 3.0 (P = 0.0199), dark-adapted oscillatory (P = 0.0265), dark-adapted 10.0 (P = 0.0166), light-adapted 3.0 (P = 0.0411), and flicker (P = 0.0361) showed significant differences. Using the density criterion, the statistical test demonstrated a significant difference between the groups in dark-adapted 3 (P = 0.0038), dark-adapted oscillatory (P = 0.0102), dark-adapted 10.0 (P = 0.0071), light-adapted 3.0 (P = 0.0319), and flicker 30 Hz (P = 0.0076). CONCLUSION: The proposed features have made it possible to distinguish between healthy and CRVO eyes. This method could be helpful in some cases with no definite diagnosis or to estimate the severity of CRVO.

Assessment of the Absolute Excitatory Level of the Retina by Flicker ERG.

Electroretinography (ERG) is important for functional diagnostics of the retina. Types of information about retinal function obtainable by ERG differ depending on recording conditions, e.g., a combination of light stimulus and adaptation. In terms of stimulation, single-flash and flicker stimuli are frequently used because response properties have been well investigated, allowing an assessment of fundamental retinal functionality; for example, how photoreceptors and bipolar cells, including signal transmission between them, are affected under pathological conditions. Usually, ERGs are recorded with a nonzero lower cutoff frequency of amplifiers to avoid certain artifacts, and additionally, responses are averaged over time so that non-event-related signals are cancelled out. However, the improved signal quality is associated with a loss of information. Especially in steady-state flicker ERG, information about the absolute baseline of recordings is missing because the prestimulus baseline is not included on the recording trace as well as because a zero response is obtained in all cases in which the signal baseline stays constant for a sufficient amount of time. In other words, it is impossible to tell from the conventional flicker ERG whether a zero signal is obtained under conditions of maximal or no excitation of the visual system. In this chapter, we describe a direct current ERG protocol (featuring a lower cutoff frequency of zero) with repetitive single flashes mimicking conventional flicker that contains a defined onset. Using this recording protocol, it is possible to assess not only the absolute excitatory level of the retina but also the development of steady-state responses from the single flash response.

The assessment of macular electrophysiology and macular morphology in patients with vitiligo.

PURPOSE: We aimed to analyze the electrophysiologic function and morphology of macula in vitiligo patients. METHODS: Seventeen patients with vitiligo and 11 healthy subjects were studied. All participants underwent multifocal electroretinography (mfERG) and spectral domain optical coherence tomography (SD-OCT) evaluations. The mfERG (P1 mfERG responses central and peripheral) and retinal layer segmentation parameters (nine ETDRS subfields) were compared in vitiligo and control groups. RESULTS: The mean P1 response amplitudes were significantly decreased in central and peripheral rings of the fovea in patients with vitiligo compared with controls (p = 0.002 and p = 0.006, respectively). There was a tendency toward a prolonged mean implicit time for both central and peripheral in patients with vitiligo compared to controls, however, with no statistical significance (p = 0.453 and p = 0.05, respectively). There was no statistically significant difference in all retinal layers thickness between two groups. CONCLUSION: In patients with vitiligo, while photoreceptor segment preserved in SD-OCT, mfERG reduced showing potential decline in central retinal function. This study showed a potential decline in central retinal function in patients with vitiligo even if they have normal fundus appearance and SD-OCT findings.

Assessment of macular function in patients with idiopathic Epiretinal membrane by multifocal Electroretinography: correlation with visual acuity and optical coherence tomography.

BACKGROUND: This study evaluates the macular function changes in patients with idiopathic macular epiretinal membrane (ERM) by multifocal electroretinography (mfERG) and their correlations with visual acuity and central macular thickness (CMT) by optical coherence tomography (OCT). METHODS: Twenty eyes of 20 patients with ERM underwent OCT and mfERG examinations. The response amplitude densities and implicit times of mfERG were compared to the control fellow eyes. Correlation analyses among visual acuity, central macular thickness and mfERG values in the central two concentric rings were performed. RESULTS: The mfERG P1 response amplitude densities in ring 1-2 and P1 implicit time in ring1 were significantly changed in epiretinal membrane eyes compared with controls (P < 0.05). Multivariate stepwise linear regression analyses showed LogMAR visual acuity was significantly correlated with CMT (P = 0.004), and also with the P1 amplitude density in ring 1 (P = 0.002). CMT showed significant correlation with P1 implicit time in ring 2 (P = 0.013). CONCLUSIONS: The mfERG abnormalities show macular function changes and correlate with visual acuity and central macular thickness in eyes with ERM. In first-order mfERG responses, P1 wave changes may be a sensitive functional measurement for ERM patients.

Electroretinographic Assessment of Inner Retinal Signaling in the Isolated and Superfused Murine Retina.

PURPOSE: Longer-lasting electroretinographic recordings of the isolated murine retina were initially achieved by modification of a phosphate-buffered nutrient solution originally developed for the bovine retina. During experiments with a more sensitive mouse retina, apparent model-specific limitations were addressed and improvements were analyzed for their contribution to an optimized full electroretinogram (ERG). MATERIAL AND METHODS: Retinas were isolated from dark-adapted mice, transferred to a recording chamber and superfused with different solutions. Scotopic and photopic ERGs were recorded with white flashes every 3 minutes. The phosphate buffer (Sickel-medium) originally used was replaced by a carbonate-based system (Ames-medium), the pH of which was adjusted to 7.7-7.8. Moreover, addition of 0.1 mM BaCl2 was investigated to reduce b-wave contamination by the slow PIII component typically present in the murine ERG. RESULTS: B-wave amplitudes were increased by the pH-shift (pH 7.4 to pH 7.7) from 22.9 ± 1.9 µV to 37.5 ± 2.5 µV. Improved b-wave responses were also achieved by adding small amounts of Ba2+ (100 µM), which selectively suppressed slow PIII components, thereby unmasking more of the true b-wave amplitude (100.0% with vs. 22.2 ± 10.7% without Ba2+). Ames medium lacking amino acids and vitamins was unable to maintain retinal signaling, as evident in a reversible decrease of the b-wave to 31.8 ± 3.9% of its amplitude in complete Ames medium. CONCLUSIONS: Our findings provide optimized conditions for ex vivo ERGs from the murine retina and suggest that careful application of Ba2+ supports reliable isolation of b-wave responses in mice. Under our recording conditions, murine retinas show reproducible ERGs for up to six hours.

7-Hexagon Multifocal Electroretinography for an Objective Functional Assessment of the Macula in 14 Seconds.

PURPOSE: We present the multifocal electroretinogram (mfERG) with a 7-hexagon array as an objective test of macular function that can be recorded in 14 s. We provide normal values and investigate its reproducibility and validity. METHODS: Healthy participants underwent mfERG testing according to International Society for Clinical Electrophysiology of Vision (ISCEV) standards using the Espion Profile/D310 multifocal ERG system (Diagnosys, LLC, Lowell, MA, USA). One standard recording of a 61-hexagon array and 2 repeated recordings of a custom 7-hexagon array were obtained. RESULTS: A total of 13 subjects (mean age 46.9 years) were included. The median response densities were 12.5 nV/deg2 in the center and 5.2 nV/deg2 in the periphery. Intereye correlations were strong in both the center (ρCenter = 0.821; p < 0.0001) and the periphery (ρPeriphery = 0.862; p < 0.0001). Intraeye correlations were even stronger: ρCenter = 0.904 with p < 0.0001 and ρPeriphery = 0.955 with p < 0.0001. Bland-Altman plots demonstrated an acceptable retest mean difference in both the center and periphery, and narrow limits of agreement. We found strong correlations of the center (ρCenter = 0.826; p < 0.0001) and periphery (ρPeriphery = 0.848; p < 0.0001), with recordings obtained by the 61-hexagon method. CONCLUSIONS: The 7-hexagon mfERG provides reproducible results in agreement with results obtained according to the ISCEV standard.

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

PURPOSE: The purpose of this study was to assess the role of various diagnostic tests in early detection of retinal changes in ß-thalassemia major patients. METHODS: Thirty-eight visually asymptomatic ß-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. RESULTS: 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). CONCLUSIONS: Full-field ERG and mfERG are more sensitive tools for detecting early retinal changes in ß-thalassemia patients compared with ophthalmoscopy, VEP, FAF imaging and OCT scans.

Teleretinography into diabetes integrated care: an Italian experience.

INTRODUCTION: Integrated care, by allowing information exchange among health professionals, improves outcomes and favours a reduction in hospital admission in diabetes. Retinal complications can be sight-threatening, and diabetic patients often miss the suggested yearly clinical examination. METHODS: Teleretinography can be easily performed in patients attending Diabetes Clinics: images are sent to a remote ophthalmologist, grading and instructions are received and forwarded to General Practitioners by a dedicated software. RESULTS: We here report the results of teleretinography performed in our Diabetes Clinic in 362 patients missing the yearly fundus examination: 253 patients showed no diabetic retinopathy, 86 a mild form, and 23 needed referral to hospital settings. CONCLUSIONS: Teleretinography is a user-friendly, time-saving and cost-effective technique, easily integrable into integrated care, allowing a better adherence to guidelines.

The Role of Multifocal Electroretinography in the Assessment of Drug-Induced Retinopathy: A Review of the Literature.

Multifocal electroretinography (mfERG) is an objective, noninvasive examination for the assessment of visual function. It enables the stimulation of multiple retinal areas simultaneously and recording of each response independently, providing a topographic measure of retinal electrophysiological activity in the central 40-50° of the retina. A clinical application of mfERG represents the assessment of retinal toxicity associated with systemic medications. Drug-induced retinopathy represents a disease that, although not common, requires early recognition: if not detected early, it may progress and cause irreversible retinal dysfunction with subsequent visual impairment. This review aims to evaluate the use of mfERG in the assessment of retinal dysfunction associated with various systemic pharmacological agents based on the currently available literature. The most commonly recognized systemic medications affecting retinal function are included, such as chloroquine and hydroxychloroquine, vigabatrin, deferoxamine, ethambutol, interferon-α, tamoxifen, digoxin, sildenafil, canthaxanthin, amiodarone and nefazodone. The role of mfERG in the early diagnosis of retinal toxicity and the evaluation of disease severity is reviewed, as well as its clinical value in monitoring disease progression or recovery after drug cessation.

Assessment of macular function, structure and predictive value of pattern electroretinogram parameters for postoperative visual acuity in patients with idiopathic epimacular membrane.

PURPOSE: To evaluate macular function and structure before and after epimacular membrane surgery and to estimate the usefulness of pattern ERG test parameters in predicting the postoperative visual acuity. METHODS: We evaluated 32 eyes of 32 patients (mean age 70.8 ± 6.7 years) before and 12 months after successful 25G pars plana vitrectomy with epimacular membrane removal and internal limiting membrane peeling. Distance best-corrected visual acuity (DBCVA-logMAR), foveal thickness (optical coherence tomography-OCT) and macular function [pattern electroretinogram-PERG (ISCEV standard): amplitudes (A) of P50- and N95-waves, implicit time (IT) of P50-wave] were assessed. To estimate the differences between the mean values of considered characteristics, the t test or Wilcoxon matched pair test was used. Correlation between preoperative data of PERG and preoperative and final DBCVA were investigated using Pearson correlation analysis. A receiver operating characteristic curve was constructed to obtain a cutoff value allowing prediction of visual prognosis. We tried to obtain the P50 and N95 amplitudes cutoff value in prediction of good visual outcome (DBCVA of 0.3 or less). RESULTS: Twelve months after surgery, mean of DBCVA significantly increased in comparison with preoperative value (0.31 ± 0.12 vs. 0.6 ± 0.15; p < 0.001) and 23/32 eyes (72 %) achieved visual improvement of two and more Snellen lines. In OCT test, the significant reduction in foveal thickness mean (313.34 ± 47.01 vs. 509.03 ± 93.88 µm; p < 0.001) was obtained. In PERG test, the significant increase in the mean amplitudes of P50- (AP50) and N95 (AN95)-waves as well as significant decrease in the mean implicit time (IT) of P50-wave were achieved (AP50: 3.41 ± 1.48 vs. 2.38 ± 1.23 µV; p < 0.001; AN95: 5.46 ± 1.72 vs. 3.75 ± 1.48 µV; p < 0.001; IT P50: 55.00 ± 3.60 vs. 56.75 ± 5.78 ms; p < 0.001). Twelve months postoperatively, DBCVA was significantly correlated with preoperative IT P50 (r = 0.39; p = 0.027), AP50 (r = -0.68; p < 0.001) and AN95 (r = -0.73; p < 0.001). CONCLUSION: Removal of idiopathic epimacular membranes with internal limiting membrane peeling not only provided increase in visual acuity and reduction in foveal thickness but also caused improvement of innermost retinal layer function in macular region. Pattern ERG test might be a valuable tool in predicting the postoperative visual acuity.

The diagnosis and assessment of visual function in Singaporean children with electrophysiology: 10-year results.

PURPOSE: To study the clinical use and efficacy of electrophysiology in children. METHODS: This was a retrospective review of all children aged <16 years, who were referred to the Visual Electrophysiology Laboratory at the Singapore National Eye Center between 2003 and 2013. RESULTS: A total of 586 children, median age 8 years (range 0.15-16), were referred for a variety of reasons including investigation of poor vision (40 %), suspected retinal disease or optic nerve/cortical dysfunction (17 %), nystagmus (13 %) and screening or monitoring of a variety of ocular or neurological conditions (12 %). The number of children with vision 6/15 or worse was 418 (71 %), and 103 (18 %) had vision 6/120 or worse in at least one eye. The most common pathology noted was retinal dystrophy or dysfunction (41 %) or optic nerve/cortical dysfunction (12 %). In 30 %, visual electrophysiology was within normal limits, and in 6 %, a conclusive diagnosis could not be obtained. CONCLUSION: Electrophysiology testing played an important role in the assessment of children and added to the clinical management of the patient.

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

PURPOSE: The authors examined macular function in preterm-born children, using multifocal ERG (mfERG). Possible alterations in P1 amplitudes, P1 amplitudes density and P1 implicit time between school-age children with history of prematurity and their peers were researched. The correlations between parameters of mfERG responses and birth weight, gestational age, macular volume and central macular thickness were verified. METHODS: A group of 18 preterm-born school-age children were analyzed (mean age 10.18 ± 1.21 years). The study group was compared to the group of 15 peers born appropriate for gestational age (mean age 10.8 ± 1.52 years). The mfERG was evaluated in all children. RESULTS: There were statistically significant differences for P1 amplitudes from ring 1 (p = 0.0001) and P1 amplitudes density from ring 1 (p = 0.0001). Calculating the correlation coefficients, we receive significant results for P1 amplitudes from ring 1 versus gestational age (r = 0.54; p = 0.026), birth weight (r = 0.54; p = 0.026) and central macular thickness (r = -0.62; p = 0.008), and for P1 amplitudes density from ring 1 versus central macular thickness (r = -0.51; p = 0.034). CONCLUSIONS: The study suggests that P1 amplitudes and P1 amplitudes density vary in preterm-born children in comparison with their peers born appropriate for gestational age, which might suggest discreet macular dysfunction. The correlation between low birth weight, early gestational age, central macular thickness and mFERG components from ring 1 might evidence that decreased bipolar cells density caused by premature birth is the result of altered development of central retina reflecting in structural anomalies of the fovea.

Assessment of Macular Function during Vitrectomy: New Approach Using Intraoperative Focal Macular Electroretinograms.

PURPOSE: To describe a new technique to record focal macular electroretinograms (FMERGs) during vitrectomy to assess macular function. METHODS: Intraoperative FMERGs (iFMERGs) were recorded in ten patients (10 eyes) who undergo vitrectomy. iFMERGs were elicited by focal macular stimulation. The stimulus light was directed to the macular area through a 25 gauge (25G) glass fiber optic bundle. Background light was delivered through a dual chandelier-type light fiber probe. Focal macular responses elicited with combinations of stimulus and background luminances were analyzed. RESULTS: A stimulus luminance that was approximately 1.75 log units brighter than the background light was able to elicit focal macular responses that were not contaminated by stray light responses. Thus, a stimulus luminance of 160 cd/m2 delivered on a background of 3 cd/m2 elicited iFMEGs from only the stimulated area. This combination of stimulus and background luminances did not elicit a response when the stimulus was projected onto the optic nerve head. The iFMERGs elicited by a 10° stimulus with a duration of 100 ms and an interstimulus interval of 150 ms consisted of an a-, b-, and d-waves, the oscillatory potentials, and the photopic negative response (PhNR). CONCLUSIONS: Focal ERGs with all components can be recorded from the macula and other retinal areas during vitreous surgery. This new technique will allow surgeons to assess the function of focal areas of the retina intraoperatively.