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Protocolo combinado de PEV y ERG en perros beagle para evaluar la integridad funcional de las vías visuales
摘要： Visual evoked potentials (VEP) and electroretinography (ERG) are known as objective and quantitative methods to analyse the functionality of visual pathways. Separately used in the ophthalmologic clinic to evaluate retina (ERG) or central visual pathways (VEP), this study designs a combined protocol with both techniques recorded in one session, and also proposes a normal data base for beagle. Twelve beagle dogs were used to design a 90-minutes protocol by using a mydriatic drug, anaesthetic protocol and a proper electrode placement. Flash stimulation technique was selected, and monocular stimulations were recorded. A large number of parameters regarding light stimulation, recording, amplification, and signal averaging were also controlled. The sequence of testing was: VEP, ERG scotopic and ERG photopic. Dogs were dark-adapted for at least 20 minutes to record VEP and scotopic ERG, and evaluated in a darkened room. Photopic ERG was tested with a prior 10 minutes light-adaptation, in an illuminated room. Characteristic waveforms were obtained. Four peaks were present and named as: P1, N1, P2, and N2 for VEP recordings. However, in ERG recordings, typical a-wave and b-wave were registered, but c-wave was not present. The proposed electrodiagnostic combined protocol in this study allows the assessment of the visual pathway integrity from retina to visual cortex in dogs. This procedure allows to collect the information in the most simple, shorter and less stressful manner for the patient.
关键词： electrodiagnosis,visual evoked potentials,electroretinography,beagle
更新于2025-09-23 15:22:29
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Deletion of both centrin 2 (CETN2) and CETN3 destabilizes the distal connecting cilium of mouse photoreceptors
摘要： Centrins (CETN1–4) are ubiquitous and conserved EF–hand family Ca2+-binding proteins associated with the centrosome, basal body, and transition zone. Deletion of CETN1 or CETN2 in mice causes male infertility or dysosmia, respectively, without affecting photoreceptor function. However, it remains unclear to what extent centrins are redundant with each other in photoreceptors. Here, to explore centrin redundancy, we generated Cetn3GT/GT single-knockout and Cetn2-/-; Cetn3GT/GT double-knockout mice. Whereas the Cetn3 deletion alone did not affect function, simultaneous ablation of Cetn2 and Cetn3 resulted in attenuated scotopic and photopic electroretinography (ERG) responses in mice at three months of age, with nearly complete retina degeneration at one year. Removal of CETN2 and CETN3 activity from the lumen of the connecting cilium (CC) destabilized the photoreceptor axoneme and reduced the CC length as early as postnatal day 22 (P22). In Cetn2-/-; Cetn3GT/GT double-knockout mice, spermatogenesis-associated 7 (SPATA7), a key organizer of the photoreceptor-specific distal CC, was depleted gradually and CETN1 was condensed to the mid-segment of the CC. Ultrastructural analysis revealed that in this double knockout, the axoneme of the CC expanded radially at the distal end, with vertically misaligned outer segment discs and membrane whorls. These observations suggest that CETN2 and CETN3 cooperate in stabilizing the CC/axoneme structure.
关键词： centriole,connecting cilium,retina degeneration,cilium,retina,electroretinography,Ca2+-binding proteins,photoreceptor,centrin 2/centrin 3 double knockout,centrin
更新于2025-09-23 15:22:29
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A Comparison of the RETeval Sensor Strip and DTL Electrode for Recording the Photopic Negative Response
摘要： Purpose: To compare the RETeval sensor strip and Dawson-Trick-Litzkow (DTL) electrodes for recording the photopic negative response (PhNR) using a portable electroretinogram (ERG) device in eyes with and without glaucoma. Methods: Twenty-six control and 31 glaucoma or glaucoma-suspect participants were recruited. Photopic ERGs were recorded with sensor strip and DTL electrodes in random order using the LKC RETeval device. Stimuli consisted of brief, red flashes (1.7 cd.s/m2) on a blue background (photopic 10 cd/m2). The PhNR amplitude was measured from baseline to trough and also expressed as a ratio over the b-wave amplitude. Results: The sensor strip-recorded PhNR amplitude was significantly attenuated (mean 6 standard deviation [SD], 4.8 6 2.1 vs. 12.7 6 4.8 lV, P , 0.0001), with lower signal-to-noise ratio (SNR; 5.5 6 2.1 vs. 8.1 6 3.9, P , 0.0001), and a trend toward a larger PhNR/b-wave ratio compared with DTL electrodes. The PhNR amplitude, implicit time and PhNR/b-wave ratio correlated with visual field mean light sensitivity, although this fell short of significance for the sensor strip recorded PhNR amplitude. The electrodes demonstrated similar intersession repeatability with a coefficient of repeatability of 627% and 628% for the DTL and sensor strip, respectively. Conclusions: Sensor strip electrodes are a viable alternative for recording reproducible PhNRs, especially when values are normalized to the b-wave. However, DTL electrodes should be considered in cases of attenuated PhNR, or in elevated noise levels, due to its better signal-to-noise quality. Translational Relevance: Sensor strip electrodes can simplify PhNR recordings in the clinic, potentially eliminating the need for an experienced operator.
关键词： electroretinography,PhNR,photopic negative response
更新于2025-09-23 15:22:29
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Multifocal electroretinogram in diabetic macular edema; Correlation with visual acuity and optical coherence tomography
摘要： Purpose: To evaluate multifocal electroretinogram (mfERG) changes in eyes with diabetic macular edema (DME) and investigate any possible correlation with optical coherence tomography (OCT) features and visual acuity (VA). Methods: Twenty?nine right eyes of 29 subjects with DME due to non?proliferative diabetic retinopathy and 30 eyes of 30 normal subjects were evaluated. All patients underwent a complete ophthalmic examination. Sixty?one scaled hexagon mfERG responses were recorded. Components of the first order kernel of N1, N2, and P1 in five concentric rings centered on the fovea, were measured in both groups. Correlation and regression analyses were performed among VA, central macular thickness (CMT) based on OCT, mfERG amplitude, and latency of the N1, N2 and P1 waves. Results: Significant differences were observed in all mfERG parameters in five?ring regions of the retina between eyes with DME versus controls (P < 0.05). There were significant correlations among VA with N2 (P = 0,001, b = 0.73) and P1 amplitudes (P = 0.001, b = ?0.84) in the central macular area, and there was a borderline association between VA and CMT (P = 0.042, b = 0.392). Conclusion: Amplitudes of mfERG components (N1, P1, and N2) are significantly reduced and their latencies are delayed in eyes with DME indicating functional impairment in the outer retina. The mfERG total amplitude was significantly correlated with VA even more than CMT, therefore the combined use of OCT and mfERG for macular evaluation may better evaluate visual status in DME patients.
关键词： Diabetes Mellitus,Multi?focal Electroretinography,Diabetic Macular Edema,Optical Coherence Tomography,Visual Acuity
更新于2025-09-23 15:21:01
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Clinically Relevant Outcome Measures for the I307N Rhodopsin Mouse: A Model of Inducible Autosomal Dominant Retinitis Pigmentosa
摘要： PURPOSE. The I307N rhodopsin (Rho) mouse is a light-inducible model of autosomal dominant retinitis pigmentosa (adRP) that may be useful in testing therapies. We investigated the time-course of retinal changes of the I307N Rho mouse with spectral-domain optical coherence tomography (SD-OCT). METHODS. SD-OCT was performed up to day 30 after light damage; electroretinography (ERG) was employed to evaluate photoreceptor function. We utilized ImageJ to analyze reflectivity of the retina. We used light and electron microscopy to assess retinal organization. We stained synaptophysin and zonula occludins-1 with immunohistochemistry to determine injury to the plexiform layers and retinal pigment epithelium (RPE). We performed lectin staining to evaluate retinal blood vessels. RESULTS. Retinal degeneration increased with longer exposures to light. An increase in retinal thickness was detected by SD-OCT on day 1 after light challenge followed by loss of the outer nuclear layer (ONL) by day 8. Degeneration was most severe in the nasal and inferior retina. Hyper-reflectivity on SD-OCT developed as early as 1 day after light exposure. Disorganization of the ONL, condensation of photoreceptor chromatin, disruption of the outer limiting membrane, and disarray of outer segments were associated with the hyper-reflectivity. Retraction of the outer plexiform synapses and resorption of the subretinal detachment contributed to retinal thinning. The RPE remained intact, whereas atrophied major retinal vessels were evident after light damage. CONCLUSIONS. Our time-course analysis of retinal degeneration in the I307N Rho mouse with SD-OCT and other outcome measures should enable the use of the mouse model in preclinical efficacy studies and mechanistic studies.
关键词： SD-OCT,rhodopsin,electroretinography,retinitis pigmentosa,hyper-reflectivity
更新于2025-09-23 15:21:01
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Test-retest variability of multifocal electroretinography in normal volunteers and short-term variability in hydroxychloroquine users
摘要： Purpose: To determine measurement variability of N1P1 amplitudes and the R1/R2 ratio in normal subjects and hydroxychloroquine users without retinopathy. Design: Retrospective, observational study. Subjects: Normal subjects (n=21) and 44 patients taking hydroxychloroquine (n=44) without retinopathy. Methods: Multifocal electroretinography (mfERG) was performed twice in one session in the 21 normal subjects and twice within 1 year in the hydroxychloroquine users, during which time no clinical change in macular status occurred. Main outcome measures: N1P1 amplitudes of rings R1–R5, the R1/R2 ratio, and coefficients of repeatability (COR) for these measurements. Results: Values for N1P1 amplitudes in hydroxychloroquine users were reduced compared with normal subjects by the known effect of age, but R1/R2 was not affected by age. The COR for R1–R5 ranged from 43% to 52% for normal subjects and from 43% to 59% for hydroxychloroquine users; for R1/R2 the COR was 29% in normal subjects and 45% in hydroxychloroquine users. Conclusion: mfERG measurements show high test-retest variability, limiting the ability of a single mfERG test to influence a decision to stop hydroxychloroquine; corroborative evidence with a different ancillary test is recommended in a suspicious case.
关键词： test-retest variability,hydroxychloroquine,multifocal electroretinography
更新于2025-09-19 17:15:36
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Dystrophin Is Required for Proper Functioning of Luminance and Red–Green Cone Opponent Mechanisms in the Human Retina
摘要： Visual information is processed in parallel pathways in the visual system. Parallel processing begins at the synapse between the photoreceptors and their postreceptoral neurons in the human retina. The integrity of this first neural connection is vital for normal visual processing downstream. Of the numerous elements necessary for proper functioning of this synaptic contact, dystrophin proteins in the eye play an important role. Deficiency of muscle dystrophin causes Duchenne muscular dystrophy (DMD), an X-linked disease that affects muscle function and leads to decreased life expectancy. In DMD patients, postreceptoral retinal mechanisms underlying scotopic and photopic vision and ON- and OFF-pathway responses are also altered.
关键词： magnocellular/parvocellular,electroretinography,Duchenne muscular dystrophy,dystrophin,retina
更新于2025-09-10 09:29:36
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Consecutive unilateral recording of the two eyes affects dark-adapted ERG responses, when compared to simultaneous bilateral recording
摘要： Purpose Our aim was to compare the electroretinographic (ERG) responses of two eyes obtained by consecutive unilateral recordings to those obtained by a simultaneous bilateral recording in sheep. Methods Eight sheep underwent two full-field ERG recordings, using two recording strategies of the standard ISCEV protocol: consecutive unilateral recordings of one eye after the other, and simultaneous bilateral recording of both eyes. The order of recording strategy within an animal (unilateral/bilateral), eye recording sequence in the unilateral session (OD/OS), and amplifier channel assignment for each eye were all randomized. To test whether duration of dark adaptation and/or anesthesia affect the results, the ISCEV protocol was recorded bilaterally in six additional eyes following 38 min of patched dark adaptation, as was done for the second eye recorded in the consecutive unilateral recordings. Results The second recorded eye in the unilateral session had significantly higher scotopic b-wave amplitudes compared to the first recorded eye and to the bilaterally recorded eyes. A-wave amplitudes of the dark-adapted mixed rod–cone responses to a high-intensity flash were also significantly higher in the second eye compared to the first eye recorded unilaterally and to the bilaterally recorded eyes. Light-adapted responses were unaffected by the recording strategy. When the ISCEV protocol was recorded after 38 min of dark adaptation, the scotopic responses were higher than in the first eyes, and similar to those of the second eyes recorded unilaterally, suggesting that indeed the longer duration of anesthesia and dark adaptation are responsible for the increased scotopic responses of the second eye. Conclusions Consecutive unilateral ERG recordings of two eyes result in higher amplitudes of the dark-adapted responses of the eye recorded second, compared to the eye recorded first and to bilaterally recorded eyes. The differences in scotopic responses can be attributed to different duration of dark adaptation and/or anesthesia of the two consecutively recorded eyes. Photopic responses are not affected. Therefore, simultaneous bilateral ERG responses should be recorded when possible, especially for evaluation of scotopic responses.
关键词： Electroretinography (ERG),Bilateral,ISCEV,Unilateral,Sheep,Dark-adapted responses
更新于2025-09-10 09:29:36
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Effects of Simvastatin on Retinal Structure and Function of a High-Fat Atherogenic Mouse Model of Thickened Bruch's Membrane
摘要： PURPOSE. To determine the effect of a statin (simvastatin) on the ultrastructure and function of the RPE, Bruch’s membrane (BM), and photoreceptor interface in a high-fat atherogenic mouse model of thickened BM. METHODS. Wild-type C57BL/6 mice (6-weeks old) were divided into three study groups according to their diet and treatment given; Group 1, normal chow diet-fed mice; Group 2, high fat diet (HFD) fed mice; and Group 3, HFD-fed mice treated with simvastatin daily for 30 weeks. All mice were followed-up for 30 weeks. The retinal morphology and function was examined in vivo using fundus imaging and electroretinography at 15- and 30-weeks follow-up. At the end of the study, at 36 weeks of age, eye tissues were collected and retinal sections were examined using light microscopy and transmission electron microscopy. RESULTS. Fundus images of the HFD-fed mice showed the presence of discrete, multiple white spots, which was signi?cantly reduced by approximately 73% in the simvastatin-treated animals. In the HFD-fed mice, there was an increase in the empty cytoplasmic vacuoles of the RPE, presence of lipid droplets in the BM, thickening and fragmentation of the elastic lamina of the BM, and a reduction in retinal function; these ultrastructural and functional changes were signi?cantly improved in the simvastatin-treated group. CONCLUSIONS. Chronic administration of simvastatin signi?cantly improves the ultrastructure and function of the RPE, BM, and photoreceptor in a high-fat atherogenic mouse model of thickened BM.
关键词： electroretinography,Bruch’s membrane,simvastatin,high-fat atherogenic mouse model,retina
更新于2025-09-09 09:28:46
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Assessing the Anatomical and Functional Efficacy of Aflibercept on Wet ARMD: An OCT and Mferg Recording
摘要： Objective: To investigate the therapeutic efficacy of aflibercept on sub-foveal choroidal neovascularization due to Age-Related Macular Degeneration (ARMD). Methods: Fifteen patients (15 eyes) with sub-foveal choroidal neovascularization due to ARMD were treated with intravitreal aflibercept. The doses were monthly for the first three months, being repeated every three months after for one year, using 2 mg of intravitreal aflibercept. A total of six aflibercept injections were, finally, performed during the 12-month study. All patients underwent a complete ophthalmic examination, including the measurement of best-corrected visual acuity, fundus examination, intraocular pressure measurement, fluorescein angiography, optical coherence tomography (OCT) scan and multifocal electroretinography (mfERG) recording, at the baseline and at the first, second, third, sixth, ninth and 12th month after the first injection of aflibercept. Two masked examiners evaluated the visual acuity based on standard Snellen charts. Results: Fifteen patients (15 eyes), of mean age 69.2 ± 4.9 years old, with sub-foveal choroidal neovascularization due to ARMD were participated in this study. The mean BCVA was 0.12 ± 0.08, 0.20 ± 0.10, 0.25 ± 0.1, 0.28 ± 0.1, 0.34 ± 0.14, 0.36 ± 0.14 and 0.40 ± 0.14 decimal, at presentation, 1st, 2nd, 3rd, 6th, 9th and 12th month, respectively. Significant differences in amplitudes but not in latencies of three rings were observed over time. Significant reductions were noted among the central retinal thickness measurements before intravitreal aflibercept and at 1st, 2nd, 3rd, 6th, 9th and 12th month (465.0 ± 161.4, 374.9 ± 139.5, 323.3 ± 113.8, 290.3 ± 85, 263.3 ± 69, 243.0 ± 60.6 and 226.9 ± 63.5, respectively). Conclusion: This is the first time that anatomical and functional improvement of the macula in patients with sub-foveal choroidal neovascularization due to ARMD was shown objectively, based on OCT and mfERG recordings. In addition, the improvement of visual acuity was noted over time. Our study supports the fact that intravitreal use of aflibercept is safe and effective in treating sub-foveal choroidal neovascularization observed in patients with ARMD.
关键词： findings,electroretinography,Macular,Aflibercept,Anatomical,Sub-foveal,Multifocal,Optical coherence tomography,choroidal neovascularization,Function,Age-related macular degeneration
更新于2025-09-09 09:28:46