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1.
J. optom. (Internet) ; 17(2): [100502], Abr-Jun, 2024. graf
Artigo em Inglês | IBECS | ID: ibc-231625

RESUMO

Background: Silicone oil is used as endotamponade following vitreoretinal surgery to maintain the retina reattached when indicated. This study investigates the hypothesis that silicone oil causes insulation effects on the retina by affecting its response to light. Methods: Electrophysiological responses to a flash stimulus were recorded using full-field electroretinography (ERG) and visual evoked potentials (VEP). Recordings were performed in 9 patients who underwent surgery for retinal detachment, before (1–2 days) and after (2–3 weeks) silicone oil removal (SOR) in both the study and the control eye. Flash ERG and VEP recordings were performed according to the ISCEV standard protocol. Results: Statistically significant differences were found in the study eye in the amplitudes of the ERG responses and their corresponding ratios, i.e. the amplitude after SOR over the amplitude before SOR, in all conditions tested. No differences were observed in the control eye. The mean ratio of photopic ERG response was 3.4 ± 2.4 for the study and 1.0 ± 0.3 for the control eye (p<0.001). The mean ratio of ERG flicker response was 3.1 ± 2.4 and 1.0 ± 0.3, respectively (p = 0.003). Scotopic flash ERG ratio was 5.0 ± 4.4 for the study and 1.3 ± 0.6 for the control eye (p = 0.012). No differences were observed for the amplitude and latency of flash VEP response after SOR. Conclusions: Silicone oil causes a reduction in flash ERG responses; no effect was found on flash VEP responses. ERGs in eyes filled with silicone oil should not be considered representative of retinal functionality, in contrast to VEPs, which are not affected by silicone oil presence.(AU)


Assuntos
Humanos , Masculino , Feminino , Descolamento Retiniano/cirurgia , Óleos de Silicone/administração & dosagem , Óleos de Silicone/efeitos adversos , Eletrorretinografia , Cirurgia Vitreorretiniana , Optometria , Visão Ocular , Retina/cirurgia , Potenciais Evocados Visuais
2.
Invest Ophthalmol Vis Sci ; 65(4): 3, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38558093

RESUMO

Purpose: To describe and evaluate a novel method to determine the validity of measurements made using cycle-by-cycle (CxC) recording techniques in patients with advanced retinal degenerations (RD) having low-amplitude flicker electroretinogram (ERG) responses. Methods: The method extends the original CxC recording algorithm introduced by Sieving et al., retaining the original recording setup and the preliminary analysis of raw data. Novel features include extended use of spectrum analysis, reduction of errors due to known sources, and a comprehensive statistical assessment using three different tests. The method was applied to ERG recordings from seven patients with RD and two patients with CNGB3 achromatopsia. Results: The method was implemented as a Windows application to processes raw data obtained from a commercial ERG system, and it features a computational toolkit for statistical assessment of ERG recordings with amplitudes as low as 1 µV, commonly found in advanced RD patients. When recorded using conditions specific for eliciting cone responses, none of the CNGB3 patients had a CxC validated response, indicating that no signal artifacts were present with our recording conditions. A comparison of the presented method with conventional 30 Hz ERG was performed. Bland-Altman plots indicated good agreement (mean difference, -0.045 µV; limits of agreement, 0.193 to -0.282 µV) between the resulting amplitudes. Within-session test-retest variability was 15%, comparing favorably to the variability of standard ERG amplitudes. Conclusions: This novel method extracts highly reliable clinical recordings of low-amplitude flicker ERGs and effectively detects artifactual responses. It has potential value both as a cone outcome variable and planning tool in clinical trials on natural history and treatment of advanced RDs.


Assuntos
Defeitos da Visão Cromática , Degeneração Retiniana , Humanos , Eletrorretinografia/métodos , Degeneração Retiniana/diagnóstico , Células Fotorreceptoras Retinianas Cones/fisiologia , Estimulação Luminosa , Retina/fisiologia
3.
Ying Yong Sheng Tai Xue Bao ; 35(3): 858-866, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38646774

RESUMO

Insect visual electrophysiological techniques are important to study the electrical characteristics of photoreceptor cells and visual neurons in insects, including electroretinography (ERG) and microelectrode intracellular recording (MIR). ERG records the changes of voltage or electric current in the retina of insects in response to different light stimuli, which occurs outside the cell. MIR records the changes in individual photoreceptor cells or visual neurons of an insect exposed to different lights, which occurs inside the cell. Insect visual electrophysiological techniques can explore the mechanism of electrophysiological response of insects' vision to light and reveal their sensitive light spectra and photoreceptor types. This review introduced the basic structure and the principle of ERG and MIR, and summarized their applications in insect researches in the past 20 years, which would provide references for elucidating the mechanism of light perception in insects and the use of insect phototropism to control pests.


Assuntos
Eletrorretinografia , Insetos , Células Fotorreceptoras de Invertebrados , Animais , Insetos/fisiologia , Eletrorretinografia/métodos , Células Fotorreceptoras de Invertebrados/fisiologia , Visão Ocular/fisiologia , Microeletrodos , Fenômenos Eletrofisiológicos , Eletrofisiologia/métodos
5.
Klin Monbl Augenheilkd ; 241(4): 510-524, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38653300

RESUMO

OBJECTIVE: Paraneoplastic retinopathy (PNR) is a rapid-onset photoreceptor and post-photoreceptor dysfunction triggered by a cross-reaction between antigens expressed by the underlying tumour and retinal proteins. The present study aims to determine the electrodiagnostic biomarkers that support the diagnosis of PNR and evaluate the effect of treatment. METHODS: A retrospective observational case-controlled study including 25 patients with suspected PNR, of which 11 patients were diagnosed with PNR. The presence of PNR was confirmed based on clinical examination, supported by colour fundus photography, fundus autofluorescence imaging, optical coherence tomography, fluorescein angiography, retinal vessel oximetry, colour test, full-field electroretinogram (ffERG), on-/off ERG, S-cone ERG, and multifocal ERG (mfERG). The relationships between the clinical symptomatology and the effect of therapy were evaluated. RESULTS: All PNR patients (Nr: 11) presented with subjective symptoms of newly reported central vision or visual field deterioration. Posterior segment findings showed a severe patchy-like retinal atrophy, attenuation of the retinal vessels, and a waxy optic disc. Optical coherence tomography revealed a discontinued ISe line, and multiple hyperreflective foci. Retinal vessel oxygen saturation was increased. Multifocal ERG revealed reduced central and paracentral responses and ffERG severely attenuated scotopic-, photopic-, on-/off- and S-cone responses. The colour vision test revealed a tritan-tetartan-weakness. Two of the PNR patients underwent rituximab therapy with no further progression and even recovery of electrodiagnostic responses.In 1 nPNR (non-paraneoplastic retinopathy) patient (total Nr: 14) pseudoxanthoma elasticum-related retinopathy was the reason for impaired vision. In 3 of 13 patients with bronchopulmonary cancer a MEK- and FGFR-inhibitor- drug toxicity was the reason for the visual deterioration. CONCLUSION: Careful investigation for signs of central and/or peripheral visual field deterioration must be performed in the presence of history of a co-existing malignancy. The possibility of PNR should be taken into account. The electrodiagnostic biomarkers, suggested in this study, may help to promptly recognise PNR and also to evaluate the effect of implemented therapy.


Assuntos
Eletrorretinografia , Síndromes Paraneoplásicas Oculares , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Síndromes Paraneoplásicas Oculares/diagnóstico , Estudos Retrospectivos , Idoso , Biomarcadores/sangue , Estudos de Casos e Controles , Adulto , Doenças Retinianas/diagnóstico , Doenças Retinianas/etiologia , Tomografia de Coerência Óptica
6.
Klin Monbl Augenheilkd ; 241(4): 533-537, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38653305

RESUMO

Electroretinography (ERG) provides crucial insights into retinal function and the integrity of the visual pathways. However, ERG assessments classically require a complicated technical background with costly equipment. In addition, the placement of corneal or conjunctival electrodes is not always tolerated by the patients, which restricts the measurement for pediatric evaluations. In this short review, we give an overview of the use of the RETeval portable ERG device (LKC Technologies, Inc., Gaithersburg, MD, USA), a modern portable ERG device that can facilitate screening for diseases involving the retina and the optic nerve. We also review its potential to provide ocular biomarkers in systemic pathologies, such as Alzheimer's disease and central nervous system alterations, within the framework of oculomics.


Assuntos
Eletrorretinografia , Desenho de Equipamento , Doenças Retinianas , Humanos , Eletrorretinografia/instrumentação , Eletrorretinografia/economia , Doenças Retinianas/diagnóstico , Análise de Falha de Equipamento , Miniaturização , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Programas de Rastreamento/instrumentação , Programas de Rastreamento/economia , Seleção Visual/instrumentação , Seleção Visual/economia , Custos de Cuidados de Saúde
7.
Int Ophthalmol ; 44(1): 121, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38427085

RESUMO

PURPOSE: To assess the relationship between structural and functional tests in mild and moderate idiopathic intracranial hypertension (IIH). METHODS: Patients with mild and moderate IIH and a control group were enrolled. Best-corrected visual acuity (BCVA), macular ganglion cell layer (MGCL) thickness, peripapillary retinal nerve fiber layer (pp RNFL) thickness, perimetric mean deviation (MD), and photopic negative responses (PhNR) of the electroretinogram were recorded. The associations between structural (pp RNFL and MGCL thickness) and functional (PhNR amplitude, MD and BCVA) parameters were assessed. RESULTS: 154 eyes from 78 subjects (74 eyes from IIH patients and 80 eyes from healthy subjects) were included in this comparative observational study. The MGCL thickness, VA, pp RNFL, and PhNR base-to-trough (BT) amplitude were significantly worse in moderate IIH. The BCVA and MD were associated with MGCL thickness only in moderate IIH. The relationship between MD and MGCL thickness started when MD fell below -5.7 dB. CONCLUSIONS: The association between functional and structural parameters varies between mild and moderate IIH. The MD and MGCL thickness outperformed in assessing disease severity in mild and moderate IIH, respectively. The association between MD and MGCL thickness could be considered in IIH severity categorization.


Assuntos
Pseudotumor Cerebral , Humanos , Eletrorretinografia , Pseudotumor Cerebral/diagnóstico , Retina , Células Ganglionares da Retina/fisiologia , Tomografia de Coerência Óptica , Campos Visuais
8.
Sci Rep ; 14(1): 5116, 2024 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-38429373

RESUMO

This prospective cross-sectional study investigated the visual function of preperimetric glaucoma (PPG) patients based on hemifield (HF) pattern electroretinogram (PERG) amplitudes. Thirty-two (32) normal subjects and 33 PPG patients were enrolled in control and PPG groups, respectively. All of the participants had undergone full ophthalmic examinations, including spectral-domain optical coherence tomography (SD-OCT), visual field (VF) examination and pattern electroretinography (PERG). The PERG parameters along with the HF ratios of SD-OCT and PERG were compared between the control and PPG groups. Pairwise Pearson's correlation coefficients and linear regression models were fitted to investigate the correlations. The PERG N95 amplitudes were significantly lower in the PPG group (P < 0.001). The smaller/larger HF N95 amplitude ratio of the PPG group was found to be smaller than that of the control group (0.73 ± 0.20 vs. 0.86 ± 0.12; P = 0.003) and showed positive correlations with affected HF average ganglion cell-inner plexiform layer (GCIPL) thickness (r = 0.377, P = 0.034) and with average GCIPL thickness (r = 0.341, P = 0.005). The smaller/larger HF N95 amplitude ratio did not significantly change with age (ß = - 0.005, P = 0.195), whereas the full-field N95 amplitude showed a negative correlation with age (ß = - 0.081, P < 0.001). HF analysis of PERG N95 amplitudes might be particularly useful for patients with early glaucoma.


Assuntos
Eletrorretinografia , Glaucoma , Humanos , Eletrorretinografia/métodos , Estudos Transversais , Estudos Prospectivos , Testes de Campo Visual/métodos , Glaucoma/diagnóstico por imagem , Tomografia de Coerência Óptica/métodos
9.
Vestn Oftalmol ; 140(1): 45-56, 2024.
Artigo em Russo | MEDLINE | ID: mdl-38450466

RESUMO

In recent years, there has been a growing interest in the contribution of neuroretinal degeneration to the pathogenesis of diabetic retinopathy (DR). PURPOSE: This study assesses the effect of the drug Retinalamin on the functional state of the retina in patients with DR using the Diopsys NOVA Vision Testing System that utilizes electrophysiological (EP) technology. MATERIAL AND METHODS: The study included patients with type 1 and 2 diabetes mellitus (DM) with DR of any stage without macular edema. Patients underwent standard ophthalmological examination and objective functional examination of the retina using the Diopsys NOVA Vision Testing System. The control group consisted of patients with type 1 and 2 DM with DR who did not receive Retinalamin. RESULTS: Significant changes in pattern electroretinography and flash electroretinography parameters were recorded in patients who received a course of Retinalamin. Two clinical examples are presented, which can be designated as the first experience of objective functional monitoring of treatment of patients with DR with Retinalamin. CONCLUSION: Retinoprotective therapy is necessary already at the early stages of DR. Electroretinography is an objective tool for functional analysis of the earliest changes in retinal cells in DR. It is necessary to use the identified "therapeutic" window for the appointment of retinoprotective agents.


Assuntos
Diabetes Mellitus Tipo 1 , Diabetes Mellitus Tipo 2 , Retinopatia Diabética , Humanos , Retinopatia Diabética/diagnóstico , Retinopatia Diabética/tratamento farmacológico , Retinopatia Diabética/etiologia , Retina/diagnóstico por imagem , Eletrorretinografia
10.
J Neurosci ; 44(14)2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38467434

RESUMO

Alterations in γ-aminobutyric acid (GABA) have been implicated in sensory differences in individuals with autism spectrum disorder (ASD). Visual signals are initially processed in the retina, and in this study, we explored the hypotheses that the GABA-dependent retinal response to light is altered in individuals with ASD. Light-adapted electroretinograms were recorded from 61 adults (38 males and 23 females; n = 22 ASD) in response to three stimulus protocols: (1) the standard white flash, (2) the standard 30 Hz flickering protocol, and (3) the photopic negative response protocol. Participants were administered an oral dose of placebo, 15 or 30 mg of arbaclofen (STX209, GABAB agonist) in a randomized, double-blind, crossover order before the test. At baseline (placebo), the a-wave amplitudes in response to single white flashes were more prominent in ASD, relative to typically developed (TD) participants. Arbaclofen was associated with a decrease in the a-wave amplitude in ASD, but an increase in TD, eliminating the group difference observed at baseline. The extent of this arbaclofen-elicited shift significantly correlated with the arbaclofen-elicited shift in cortical responses to auditory stimuli as measured by using an electroencephalogram in our prior study and with broader autistic traits measured with the autism quotient across the whole cohort. Hence, GABA-dependent differences in retinal light processing in ASD appear to be an accessible component of a wider autistic difference in the central processing of sensory information, which may be upstream of more complex autistic phenotypes.


Assuntos
Transtorno do Espectro Autista , Masculino , Adulto , Feminino , Humanos , Transtorno do Espectro Autista/tratamento farmacológico , Retina , Eletroencefalografia , Ácido gama-Aminobutírico , Eletrorretinografia
11.
Doc Ophthalmol ; 148(2): 75-85, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38488946

RESUMO

The pattern electroretinogram (PERG) is a localized retinal response evoked by a contrast-reversing pattern, usually a black and white checkerboard, which provides information about macular and retinal ganglion cell function. This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV; www.iscev.org ) presents an updated and revised Standard for clinical PERG testing. This replaces the 2013 and all earlier versions. Minimum protocols for basic PERG stimuli, recording methods and reporting are specified, to promote consistency of methods for diagnosis and monitoring purposes, while responding to evolving clinical practices and technology. The main changes in the updated ISCEV Standard for clinical PERG include expanded guidance about large stimulus fields, stimulus parameters for simultaneous PERG and pattern visual evoked potential recording, baseline drift correction, and use of consistent ambient room lighting. These changes aim to provide a clinically relevant document about current practice which will facilitate good quality recordings and inter-laboratory comparisons.


Assuntos
Eletrorretinografia , Potenciais Evocados Visuais , Eletrorretinografia/métodos , Retina , Visão Ocular , Células Ganglionares da Retina
12.
PLoS One ; 19(3): e0300045, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38536853

RESUMO

Photoreceptor cell death can cause progressive and irreversible visual impairments. Still, effective therapies on retinal neuroprotection are not available. Hypoxia-inducible factors (HIFs) are transcriptional factors which strongly regulate angiogenesis, erythropoiesis, intracellular metabolism, and programed cell death under a hypoxic or an abnormal metabolic oxidative stress condition. Therefore, we aimed to unravel that inhibition of HIFs could prevent disease progression in photoreceptor cell death, as recent studies showed that HIFs might be pathologic factors in retinal diseases. Adult male balb/cAJcl (8 weeks old; BALB/c) were used to investigate preventive effects of a novel HIF inhibitor halofuginone (HF) on a murine model of light-induced retinopathy. After intraperitoneal injections of phosphate-buffered saline (PBS) or HF (0.4 mg/kg in PBS) for 5 days, male BALB/c mice were subjected to a dark-adaption to being exposed to a white LED light source at an intensity of 3,000 lux for 1 hour in order to induce light-induced retinal damage. After extensive light exposure, retinal damage was evaluated using electroretinography (ERG), optical coherence tomography (OCT), and TUNEL assay. Light-induced retinal dysfunction was suppressed by HF administration. The amplitudes of scotopic a-wave and b-wave as well as that of photopic b-wave were preserved in the HF-administered retina. Outer retinal thinning after extensive light exposure was suppressed by HF administration. Based on the TUNEL assay, cell death in the outer retina was seen after light exposure. However, its cell death was not detected in the HF-administered retina. Halofuginone was found to exert preventive effects on light-induced outer retinal cell death.


Assuntos
Piperidinas , Quinazolinonas , Degeneração Retiniana , Camundongos , Masculino , Animais , Degeneração Retiniana/tratamento farmacológico , Degeneração Retiniana/etiologia , Degeneração Retiniana/prevenção & controle , Modelos Animais de Doenças , Retina/patologia , Eletrorretinografia
13.
J Alzheimers Dis ; 98(1): 53-67, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38363610

RESUMO

Background: The clinical features of posterior cortical atrophy (PCA), a rare condition often caused by Alzheimer's disease, have been recently defined, while little is known about its neurophysiological correlates. Objective: To describe neurophysiological alterations of the visual pathway as assessed using visual field test (VF), visual evoked potentials (VEP), and electroretinogram (ERG) in PCA patients. Methods: Studies reporting VF, VEPs, and ERG in PCA patients were selected according PRISMA method. Of the 323 articles that emerged from the literature, 17 included the outcomes of interest. To these data, we added those derived from a patient cohort enrolled at our clinic. Results: The literature review included 140 patients, half of them (50%) presented with homonymous hemianopia or quadrantanopia. VEPs were available in 4 patients (2 normal findings, 1 decreased amplitude, and 1 increased latency) and ERG in 3 patients (substantially normal findings). Our case series included 6 patients, presenting with homonymous lateral hemianopia in 50% and contralateral cortical atrophy. VEPs showed normal amplitude in 66-83% according to the stimulation check, and increased latency in 67% in absence of myelin damage on MRI. Latency was increased in both eyes in 50% and only on one side in the other 50%. Such alterations were observed in patients with more severe and symmetric atrophy. ERG showed normal findings. Conclusions: Neurophysiological investigations of the visual pathway in PCA are almost absent in literature. Alterations involve both amplitude and latency and can be also monocular. A multiple-point involvement of the optical pathway can be hypothesized.


Assuntos
Doenças Neurodegenerativas , Vias Visuais , Humanos , Vias Visuais/diagnóstico por imagem , Potenciais Evocados Visuais , Eletrorretinografia , Atrofia
14.
Eur J Pharmacol ; 968: 176384, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38342360

RESUMO

Basal electroretinogram (ERG) oscillations have shown predictive value for modifiable risk factors for type 2 diabetes. However, their origin remains unknown. Here, we seek to establish the pharmacological profile of the low delta-like (δ1) wave in the mouse because it shows light sensitivity in the form of a decreased peak frequency upon photopic exposure. Applying neuropharmacological drugs by intravitreal injection, we eliminated the δ1 wave using lidocaine or by blocking all chemical and electrical synapses. The δ1 wave was insensitive to the blockade of photoreceptor input, but was accelerated when all inhibitory or ionotropic inhibitory receptors in the retina were antagonized. The sole blockade of GABAA, GABAB, GABAC, and glycine receptors also accelerated the δ1 wave. In contrast, the gap junction blockade slowed the δ1 wave. Both GABAA receptors and gap junctions contribute to the light sensitivity of the δ1 wave. We further found that the day light-activated neuromodulators dopamine and nitric oxide donors mimicked the effect of photopic exposure on the δ1 wave. All drug effects were validated through light flash-evoked ERG responses. Our data indicate that the low δ-like intrinsic wave detected by the non-photic ERG arises from an inner retinal circuit regulated by inhibitory neurotransmission and nitric oxide/dopamine-sensitive gap junction-mediated communication.


Assuntos
Diabetes Mellitus Tipo 2 , Dopamina , Camundongos , Animais , Dopamina/farmacologia , Fotofobia , Estimulação Luminosa , Retina , Eletrorretinografia , Neurotransmissores/farmacologia , Receptores de GABA-A , Ácido gama-Aminobutírico/farmacologia
15.
J AAPOS ; 28(2): 103853, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38378129

RESUMO

We report the case of an otherwise healthy 6-year-old girl presenting with poor visual acuity, photophobia, and abnormal eye and head movements who was initially diagnosed with spasmus nutans. A remote history of presumed viral cardiomyopathy and further electroretinography testing raised suspicion for Alström syndrome. She was diagnosed with a novel ALMS1 variant.


Assuntos
Síndrome de Alstrom , Nistagmo Patológico , Espasmos Infantis , Feminino , Humanos , Criança , Nistagmo Patológico/diagnóstico , Síndrome de Alstrom/diagnóstico , Espasmos Infantis/diagnóstico , Eletrorretinografia , Diagnóstico Diferencial , Proteínas de Ciclo Celular
16.
Ophthalmic Physiol Opt ; 44(3): 605-612, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38351866

RESUMO

PURPOSE: To explore the mechanisms of cone sensitivity loss in retinitis pigmentosa by combining two-colour perimetry with threshold versus intensity (tvi) testing. METHODS: Seven subjects with autosomal recessive retinitis pigmentosa and 10 normal subjects were recruited and underwent perimetric testing of one eye using 480- and 640-nm Goldman size V targets presented under scotopic conditions (no background illumination) and against a white background ranging in luminance from -1.5 to 2 log cd m-2 in 0.5 log cd m-2 steps. Data were fitted with tvi functions of the form logT = logT0 + log ((A + A0)/A0)n, where T is the threshold, T0 is the absolute threshold, A is the background intensity, A0 is the 'dark-light' constant and n is a gain constant. RESULTS: Reliable tvi functions could not be obtained within the region of the visual field corresponding to loss of the ellipsoid zone on optical coherence tomography. At fixation, changes in both T0 and A0 were observed, consistent with a d1 mechanism loss, which resulted in an upwards and rightwards shift of the tvi function. Losses at [±3°, ±3°] demonstrated changes in T0, consistent with a d3 mechanism loss, resulting in an upwards translation of the tvi curve. CONCLUSIONS: Although the absolute cone threshold was elevated at each location, shifts in the tvi function (so-called d1 mechanism loss) at fixation minimise threshold elevation in the presence of white adapting backgrounds, such as those typically employed in standard two-colour perimetry. At more peripheral testing locations, changes in threshold occurred independent of background luminance (so-called d3 mechanism loss). These findings suggest that backgrounds which selectively adapt rods while maintaining cones at, or near, absolute threshold may be preferable to conventional two-colour perimetry for assessing loss of cone sensitivity, especially at the point of fixation.


Assuntos
Células Fotorreceptoras Retinianas Cones , Retinite Pigmentosa , Humanos , Adaptação à Escuridão , Retinite Pigmentosa/diagnóstico , Campos Visuais , Visão Ocular , Testes de Campo Visual/métodos , Eletrorretinografia
17.
Sci Rep ; 14(1): 3520, 2024 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-38347052

RESUMO

To assess full-field electroretinogram findings in long-term type 1 diabetes patients without diabetic retinopathy. Prospective study including 46 eyes of 23 patients with type 1 diabetes and 46 age-matched healthy eyes evaluated by the RETI-port/scan21 and the portable system RETeval following ISCEV guidelines. The average duration of diabetes was 28.88 ± 8.04 years. In scotopic conditions, using the RETI-port/scan21, diabetic patients showed an increase in b-wave implicit time (IT) (p = 0.017) with the lowest stimuli; a diminished b-wave amplitude (p = 0.005) in the mixed response, an increased IT (p = 0.004) with the high-intensity stimuli and an OP2 increased IT (p = 0.008) and decreased amplitude (p = 0.002). Under photopic conditions, b-wave amplitude was lower (p < 0.001) and 30-Hz flicker response was diminished (p = 0.021). Using the RETeval, in scotopic conditions, diabetic patients showed a reduction in the rod b-wave amplitude (p = 0.009), an increase in a-wave IT with the 280 Td.s stimulus (p = 0.005). OP2 had an increased IT and diminished amplitude (p = 0.003 and p = 0.002 respectively). 16 Td.s flicker showed an increased IT (p = 0.008) and diminished amplitude (p = 0.048). Despite variations in values between both systems, nearly all results displayed positive correlations. Long-term type 1 diabetes patients without diabetic retinopathy exhibit alterations in scotopic conditions, as evidenced by both conventional and portable electroretinogram devices. These findings suggest a modified retinal function, particularly in rod-driven pathways, even in the absence of vascular signs.


Assuntos
Diabetes Mellitus Tipo 1 , Retinopatia Diabética , Humanos , Retinopatia Diabética/diagnóstico , Estudos Prospectivos , Retina , Eletrorretinografia , Estimulação Luminosa , Regulador Transcricional ERG
18.
Exp Eye Res ; 241: 109847, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38401854

RESUMO

Ivabradine, a hyperpolarization-activated cyclic nucleotide-gated (HCN) channel inhibitor, has been reported to induce photosensitivity-related visual disturbances such as phosphene in humans. Ivabradine-induced visual disturbances are caused by inhibition of HCN channels in the retina, and the mechanisms have been verified using HCN channel knockout mice and electroretinography (ERG). However, in rats, classical ERG using single flash light stimulus with standard analyses of waveform amplitude and latency has not revealed abnormal retinal function after administration of ivabradine. To verify whether retinal dysfunction after ivabradine administration was detectable in rats, we performed ERG using multistep flash light stimulation at the time when plasma concentration of ivabradine was high. Furthermore, the mechanism of the change in the waveform that appeared after the b-wave was investigated. Ivabradine and cilobradine, a selective HCN channel inhibitor, were administered subcutaneously to rats at 4-40 mg/kg as a single dose, and flash or long-duration ERG recordings at each light stimulus luminance were conducted 1.5 h after administration. Plasma and retinal concentrations of both compounds were measured immediately after the ERG recordings. In the flash ERG, prolongation of a- and/or b-wave latencies were detected at each light stimulus, and dose-dependent waveform changes after the b-wave were recorded at the specific light stimulus luminance for both compounds. These ERG changes increased in response to increasing plasma and retinal concentrations for both ivabradine and cilobradine. In the long-duration light stimulus ERG, a change in the waveform of the b-wave trough and attenuation of the c-wave were recorded, suggesting that the feedback control in the photoreceptor cells may be inhibited. This study revealed that the retinal dysfunction by HCN channel inhibitors in rats can be detected by multistep light stimulus ERG. Additionally, we identified that the inhibition of feedback current and the sustained responses in the photoreceptor cells cause the retinal dysfunction of HCN channel inhibitors in rats.


Assuntos
Eletrorretinografia , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização , Camundongos , Humanos , Ratos , Animais , Ivabradina , Retina , Visão Ocular , Transtornos da Visão , Camundongos Knockout , Estimulação Luminosa
19.
Exp Eye Res ; 240: 109826, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38340947

RESUMO

Retinitis pigmentosa (RP) is an inherited retinal disorder characterized by the degeneration of photoreceptors. RhoP23H/+ mice, which carry a Pro23His mutation in the RHODOPSIN (Rho) gene, are one of the most studied animal models for RP. However, except for the photoreceptors, other retinal neural cells have not been fully investigated in this model. Here, we record the temporal changes of the retina by optical coherence tomography (OCT) imaging of the RhoP23H/+ mice, from early to mid-phase of retinal degeneration. Based on thickness analysis, we identified a natural retinal thickness adaption in wild-type mice during early adulthood and observed morphological compensation of the inner retina layer to photoreceptor degeneration in the RhoP23H/+ mice, primarily on the inner nuclear layer (INL). RhoP23H/+ mice findings were further validated via: histology showing the negative correlation of INL and ONL thicknesses; as well as electroretinogram (ERG) showing an increased b-wave to a-wave ratio. These results unravel the sequential morphologic events in this model and suggest a better understanding of retinal degeneration of RP for future studies.


Assuntos
Degeneração Retiniana , Retinite Pigmentosa , Camundongos , Animais , Degeneração Retiniana/diagnóstico , Degeneração Retiniana/genética , Degeneração Retiniana/patologia , Rodopsina/genética , Retina/patologia , Retinite Pigmentosa/genética , Retinite Pigmentosa/patologia , Eletrorretinografia , Modelos Animais de Doenças
20.
Doc Ophthalmol ; 148(2): 87-95, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38416305

RESUMO

PURPOSE: The steady-state pattern electroretinogram (ssPERG) is used to assess retinal ganglion cell function in a variety of research contexts and diagnostic applications. In certain groups of patients or study participants, stable central fixation of the stimulus is not guaranteed. The present study aimed at assessing the effects of misfixation on the ssPERG response to checkerboard reversal stimuli. METHODS: Using two check sizes (0.8° and 15°), we compared ssPERG responses for several amounts of fixation deviation, ranging from 0° to 19° horizontally and from 0° to 14° diagonally. The stimulus area extended to 15° eccentricity, stimulus reversal rate was 15/s. RESULTS: Up to around 7° eccentricity, there was no sizable effect of fixation deviation under most conditions. Effects were somewhat larger for nasal than for temporal deviation, in particular for small checks. Diagonal deviation was associated with a response to luminance onset/offset at 7.5 Hz (subharmonic of the reversal rate), most prominently when the interior of a large check was fixated. CONCLUSION: Generally, moderate inaccuracies of fixation do not have a sizable effect on ssPERG amplitude. However, with large checks, the luminance response has to be considered.


Assuntos
Eletrorretinografia , Reconhecimento Visual de Modelos , Humanos , Reconhecimento Visual de Modelos/fisiologia , Células Ganglionares da Retina/fisiologia
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