Pattern Electroretinogram Research Articles

Use of Electrophysiology in the Diagnosis of Optic Nerve Disorders

Visual electrodiagnostic tests are non invasive, easily applicable that enable objective evaluation of the functions of the visual pathways. The most preferred among these test are; electroretinography (ERG), pattern electroretinography (PERG), electrooculography (EOG) and visual evoked potential (VEP). ERG is used to evaluate retinal functions especially rod and cone responses. PERG is used to evaluate functions of macular and retinal ganglion cells. EOG is used to evaluate retinal pigment epithelium functions. VEP is preferred method for evaluating the visual pathways up to the optic nerve and occipital cortex as a whole. Photopic negative response (PhNR) is originates from the electrical activity of amacrine and glial cells and also mostly retinal ganglion cells. In this study, VEP, PERG and PhNR tests which are the most preferred in the diagnosis of optic nerve disorders, will be mainly mentioned.

Diagnosing retinal disorders with artificial intelligence: the role of large language models in interpreting pattern electroretinography data

Aims: To evaluate the diagnostic accuracy of Claude-3, a large language model, in detecting pathological features and diagnosing retinitis pigmentosa and cone-rod dystrophy using pattern electroretinography data. Methods: A subset of pattern electroretinography measurements from healthy individuals, patients with retinitis pigmentosa and cone-rod dystrophy was randomly selected from the PERG-IOBA dataset. The pattern electroretinography and clinical data, including age, gender, visual acuities, were provided to Claude-3 for analysis and diagnostic predictions. The model’s accuracy was assessed in two scenarios: “first choice,” evaluating the accuracy of the primary differential diagnosis and “top 3,” evaluating whether the correct diagnosis was included within the top three differential diagnoses. Results: A total of 46 subjects were included in the study: 20 healthy individuals, 13 patients with retinitis pigmentosa, 13 patients with cone-rod dystrophy. Claude-3 achieved 100% accuracy in detecting the presence or absence of pathology. In the “first choice” scenario, the model demonstrated moderate accuracy in diagnosing retinitis pigmentosa (61.5%) and cone-rod dystrophy (53.8%). However, in the “top 3” scenario, the model’s performance significantly improved, with accuracies of 92.3% for retinitis pigmentosa and 76.9% for cone-rod dystrophy. Conclusion: This is the first study to demonstrate the potential of large language models, specifically Claude-3, in analyzing pattern electroretinography data to diagnose retinal disorders. Despite some limitations, the model’s high accuracy in detecting pathologies and distinguishing between specific diseases highlights the potential of large language models in ocular electrophysiology. Future research should focus on integrating multimodal data, and conducting comparative analyses with human experts.

A comprehensive dataset of pattern electroretinograms for ocular electrophysiology research

The Pattern Electroretinogram (PERG) is an essential tool in ophthalmic electrophysiology, providing an objective assessment of the central retinal function. It quantifies the activity of cells in the macula and the ganglion cells of the retina, assisting in the differentiation of macular and optic nerve conditions. In this study, we present the IOBA-PERG dataset, an extensive collection of 1354 transient PERG responses accessible on the PhysioNet repository. These recordings were conducted at the Institute of Applied Ophthalmobiology (IOBA) at University of Valladolid, over an extended period spanning nearly two decades, from 2003 to 2022. The dataset includes 336 records, ensuring at least one PERG signal per eye. The dataset thoughtfully includes demographic and clinical data, comprising information such as age, gender, visual acuity measurements, and expert diagnoses. This comprehensive dataset fills a gap in ocular electrophysiological repositories, enhancing ophthalmology research. Researchers can explore a broad range of eye-related conditions and diseases, leading to enhanced diagnostic accuracy, innovative treatment strategies, methodological advancements, and a deeper understanding of ocular electrophysiology.

TwinF interface inhibitor FP802 prevents retinal ganglion cell loss in a mouse model of amyotrophic lateral sclerosis

Motor neuron loss is well recognized in amyotrophic lateral sclerosis (ALS), but research on retinal ganglion cells (RGCs) is limited. Ocular symptoms are generally not considered classic ALS symptoms, although RGCs and spinal motor neurons share certain cell pathologies, including hallmark signs of glutamate neurotoxicity, which may be triggered by activation of extrasynaptic NMDA receptors (NMDARs). To explore potential novel strategies to prevent ALS-associated death of RGCs, we utilized inhibition of the TwinF interface, a new pharmacological principle that detoxifies extrasynaptic NMDARs by disrupting the NMDAR/TRPM4 death signaling complex. Using the ALS mouse model SOD1G93A, we found that the small molecule TwinF interface inhibitor FP802 prevents the loss of RGCs, improves pattern electroretinogram (pERG) performance, increases the retinal expression of Bdnf, and restores the retinal expression of the immediate early genes, Inhibin beta A and Npas4. Thus, FP802 not only prevents, as recently described, death of spinal motor neurons in SOD1G93A mice, but it also mitigates ALS-associated retinal damage. TwinF interface inhibitors have great potential for alleviating neuro-ophthalmologic symptoms in ALS patients and offer a promising new avenue for therapeutic intervention.

Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of Glaucoma.

Glaucoma is the second leading cause of blindness worldwide and is, in most cases, a consequence of elevated intraocular pressure (IOP), ultimately resulting in the death of retinal ganglion cells (RGCs). Current treatments are mostly focused on normalizing IOP, but we propose the additional use of neuroprotective agents, including methylene blue (MB), to block the loss of RGCs. Wistar rats were subjected to episcleral vein cauterization (EVC) in the left eye while the right eye was sham-operated. One week later, they were divided into two groups, which were injected with either 2.0 mg/kg MB or phosphate-buffered saline (PBS), twice a day, for 7 days. Fifteen days after surgery, rats were tested with scotopic electroretinography (ERG) or pattern electroretinography (PERG). After sacrifice, the number of RGCs and the thickness of the inner retina (IR) were evaluated both in the peripheral and central areas of the retina. Scotopic ERG showed a marked reduction (p < 0.0001) on the a- and b-wave amplitude and oscillatory potential (OP) complexity of the eyes subjected to EVC. These parameters were significantly (p < 0.01) restored by the application of MB. PERG indicated that EVC was responsible for a very significant decrease in N2 amplitude (p < 0.0001) and prolongation of N2 implicit time (p < 0.0001). Treatment with MB significantly restored N2 amplitude (p < 0.0001). In parallel with the ERG results, morphological analysis showed a significant loss of RGCs (p < 0.0001) and IR thickness (p < 0.0001) in both the peripheral and central retinas subjected to EVC, which was significantly prevented (p < 0.0001) by MB treatment. We have shown that MB treatment can be effective in preventing physiological and morphological hallmarks of optic neuropathy in a model of ocular hypertension, which faithfully recapitulates human open-angle glaucoma. Due to its high safety profile, this drug could therefore represent a new pharmacologic strategy to prevent vision loss in glaucoma patients.

Lack of ceramide synthase 5 protects retinal ganglion cells from ocular hypertensive injury

Ceramides with varying acyl-chain lengths can have unique biological actions and hence, cellular responses to ceramides may depend not on their overall concentration but on that of individual ceramide species. The purpose of this study was to determine individual ceramide species impacting retinal ganglion cell (RGC) loss under the ocular hypertensive condition.Induced pluripotent stem cell (iPSC)-derived RGCs and primary cultures of human astrocytes were used to determine the effect of individual ceramide species on both RGC viability and astrocyte secretion of inflammatory cytokines in vitro. In in vivo experiments with wild-type (WT) and ceramide synthase 5 (CerS5) knockout mice, intraocular pressure was unilaterally elevated with microbead injection. Retinal function and morphology were evaluated using pattern electroretinography (pERG) and immunofluorescence, respectively. Ceramide levels were determined by LC-MS/MS analysis.Exposure to C16:0-, C18:0-, C18:1-, C20:0- and C24:0-ceramides significantly reduces RGC viability in vitro, with the very long chain C24:0-ceramide being the most neurotoxic; treatment with C18:0-, C18:1- and C24:0-ceramides stimulates an increase of TNF-α secretion by astrocytes. The retinas of CerS5 KO mice have significantly reduced levels of C16:0- and C18:1-ceramides compared to WT; ocular hypertensive eyes of these mice maintain higher pERG amplitudes and RGC numbers compared to WT.Individual ceramides with different chain lengths have different effects on RGCs and astrocytes. Our results demonstrate that suppressing C16:0- and C18:1-ceramide species effectively protects RGCs against ocular hypertensive injury. These results provide a basis for targeting specific ceramide species in the treatment of glaucoma.

Agonism of β3-Adrenoceptors Inhibits Pathological Retinal Angiogenesis in the Model of Oxygen-Induced Retinopathy.

In response to hypoxia, sympathetic fibers to the retina activate β-adrenoceptors (β-ARs) that play an important role in the regulation of vascular and neuronal functions. We investigated the role of β3-AR using the mouse model of oxygen-induced retinopathy (OIR). Mouse pups were exposed to 75% oxygen at postnatal day 7 (PD7) followed by a return to room air at PD12. The β3-AR preferential agonist BRL37344 was subcutaneously administered once daily at different times after the return to room air. At PD17, the OIR mice underwent flash and pattern electroretinogram. After sacrifice, retinal wholemounts were used for vessel staining or immunohistochemistry for astrocytes, Müller cells, or retinal ganglion cells (RGCs). In retinal homogenates, the levels of markers associated with neovascularization (NV), the blood-retinal barrier (BRB), or astrocytes were determined by western blot, and quantitative reverse-transcription polymerase chain reaction was used to assess β3-AR messenger. Administration of the β3-AR antagonist SR59230A was performed to verify BRL37344 selectivity. β3-AR expression is upregulated in response to hypoxia, but its increase is prevented by BRL37344, which counteracts NV by inhibiting the pro-angiogenic pathway, activating the anti-angiogenic pathway, recovering BRB-associated markers, triggering nitric oxide production, and favoring revascularization of the central retina through recovered density of astrocytes that ultimately counteracts NV in the midperiphery. Vasculature rescue prevents dysfunctional retinal activity and counteracts OIR-associated retinal ganglion cell loss. β3-AR has emerged as a crucial intermediary in hypoxia-dependent NV, suggesting a role of β3-AR agonists in the treatment of proliferative retinopathies.

Retinal Toxicity Assessment Following Vitreoretinal Surgery: A Comparison of Silicone Oil and Perfluoropropane Tamponade Using Diopsys® NOVA™

Purpose This study aimed to assess and compare the retinal toxicity associated with silicone oil (SO) and perfluoropropane (C3F8) tamponade following vitreoretinal surgery for fresh rhegmatogenous retinal detachment (RRD), utilizing the office-based Diopsys® NOVA™ system for evaluation. Methods Patients who underwent vitreoretinal surgery for fresh RRD and had SO (group 1) or C3F8 (group 2) tamponade were included in a prospective analysis. Flicker full field electroretinography (ffERG) and pattern electroretinography (PERG) tests were performed at 6 months postoperatively. Results Postoperative best corrected visual acuity (logMAR) was significantly different in group 1 and group 2 patients, 0.48 ± 0.3 and 0.30 ± 0.2, respectively. No significant disparities were found in demographic variables. Flicker ffERG and PERG recordings revealed notable alterations in retinal function parameters in the group 1 compared to the group 2. Conclusion Our findings suggest a correlation between SO tamponade and retinal dysfunction, evidenced by office-based ERG measurements. The Diopsys® NOVA™ protocol offers clinical ease in assessing retinal function. Further controlled studies are essential to validate these findings and guide clinical practice effectively.

Ambient lighting alters pattern electroretinogram P50 peak time and spatial sensitivity

PurposeOur aim was to explore the effect of ambient lighting on the pattern ERG (PERG).MethodsWe compared PERGs recorded in two conditions; room lights on and room lights off. PERGs from 21 adult participants were recorded from each eye to high contrast checks of 50’ side width, reversing 3rps in a large (30°) and then standard (15°) field. This was performed first in lights-ON conditions, then 2 min after the room lights were switched off. A minimum of 2 averages of 300 trials were acquired for each condition. A subset of 10 participants had PERGs recorded to a 50’ check width with a range of stimulus contrasts (96–18%), also to a range of different check widths (100’–12’) at high contrast in both ambient lighting conditions in a 30° field.ResultsThe lights-ON P50 median peak time (PT) was 3 ms earlier than the lights-OFF P50 from the 30° field (range 0–5 ms) and 15° field (range 0–6 ms). The earlier lights-ON P50 PT was evident at different stimulus contrasts, even after accounting for stimulus contrast reductions associated with stray ambient lighting in lights-ON conditions. Lights-OFF and lights-ON P50 PT were similar to different check widths; the lights-OFF P50 PT to a 50’ check width matched the lights-ON P50 PT to a 25’ check width.ConclusionPERG P50 PT in lights-ON ambient light conditions can be earlier than in lights-OFF ambient light conditions. The difference in P50 PT with ambient light may reflect alterations in spatial sensitivity associated with retinal adaptation. These results emphasise the clinical importance of consistent ambient lighting for PERG recording and calibration.

Correlation of Visual System Biomarkers With Motor Deficits in Experimental Autoimmune Encephalomyelitis-Optic Neuritis.

Experimental autoimmune encephalomyelitis (EAE) scoring, the most commonly used primary outcome metric for an in vivo model of multiple sclerosis (MS), is highly variable and subjective. Here we explored the use of visual biomarkers in EAE as more objective and clinically relevant primary outcomes. Motor impairment in myelin oligodendrocyte glycoprotein-immunized C57BL/6J mice was quantified using a five-point EAE grading scale. Pattern electroretinography (pERG) and retinal ganglion cell/inner plexiform layer (RGC/IPL) complex thickness were measured 60 days after induction. Optic nerve histopathology was analyzed at endpoint. EAE mice displayed motor impairments ranging from mild to severe. Significant correlations were seen between pERG amplitude and last EAE score, mean EAE score, and cumulative EAE score. Optical coherence tomography (OCT) analysis demonstrated a significant correlation between thinning of the RGC/IPL complex and both EAE score and pERG amplitude. Optic nerve histopathology showed significant correlations between demyelination and cumulative EAE score, pERG amplitude, and RGC/IPL complex thickness, as well as between immune cell infiltration and cumulative EAE score, pERG amplitude, and RGC/IPL complex thickness in EAE mice. Unlike EAE scoring, pERG and OCT show direct measurement of retinal structure and function. Therefore we conclude that visual outcomes are well suited as a direct assessment of optic nerve involvement in this EAE model of MS while also being indicative of motor impairment. Standardizing directly translatable measurements as primary outcome parameters in the murine EAE model could lead to more rapid and relevant testing of new therapeutic approaches for mitigating MS.

Characterization of a monkey model with experimental retinal damage induced by N-methyl-D-aspartate.

N-methyl-D-aspartate (NMDA)-induced retinal damage has been well studied in rodents, but the detailed mechanisms have not yet been characterized in nonhuman primates. Here, we characterized the retinal degenerative effects of NMDA on rhesus monkeys in vivo. NMDA saline or saline-only control was injected intravitreally to the randomly assigned eyes and contralateral eyes of four rhesus monkeys, respectively. The structural and functional changes of retina were characterized by optical coherence tomography and electroretinography on days 0, 4, 30 and 60 post injection. Both optic discs and macular areas of the NMDA-injected eyes initially presented with a transient retinal thickening, followed by continued retinal thinning. The initial, transient retinal thickening has also been observed in glaucoma patients, but this has not been reported in rodent NMDA models. This initial response was followed by loss of retina ganglion cells (RGCs), which is similar to glaucomatous optic neuropathy and other RGC-related retinal degenerations. The amplitudes of both the photopic negative response and pattern electroretinogram decreased significantly and remained low until the end of the study. Thus, the NMDA monkey model may serve as a more clinically relevant animal model of retinal damage.

Cellular senescence mediates retinal ganglion cell survival regulation post-optic nerve crush injury.

Traumatic optic neuropathy refers to optic nerve (ON) injury by trauma, including explosion and traffic accident. Retinal ganglion cell (RGC) death is the critical pathological cause of irreversible visual impairment and blindness in ON injury. We previously investigated the patterns of 11 modes of cell death in mouse retina post-ON injury. Here we aimed to identify additional signalling pathways regulating RGC survival in rodents post-ON injury. RNA sequencing analysis identified the upregulation of inflammation and cellular senescence-related genes in retina post-ON injury, which were confirmed by immunoblotting and immunofluorescence analyses. Increased expression of senescence-associated β-galactosidase (SA-βgal) in RGCs and activation of microglia were also found. Transforming growth factor-β receptor type II inhibitor (LY2109761) treatment suppressed p15Ink4b and p21Cip1 protein and SA-βgal expression and promoted RGC survival post-ON injury with decreasing the expression of cell death markers in retina. Consistently, senolytics (dasatinib and quercetin) treatments can promote RGC survival and alleviate the reduction of ganglion cell complex thickness and pattern electroretinography activity post-ON injury with reducing SA-βgal, p15Ink4b, p21Cip1, microglial activation and cell death marker expression. In summary, this study revealed the activation of cellular senescence in rodent retina post-ON injury and contribute to RGC survival regulation. Targeting cellular senescence can promote RGC survival after ON injury, suggesting a potential treatment strategy for traumatic optic neuropathy.

CDH23-Associated Usher Syndrome: Clinical Features, Retinal Imaging, and Natural History.

The purpose of this study was to analyze the clinical spectrum and natural history of CDH23-associated Usher syndrome type ID (USH1D). Molecularly-confirmed individuals had data extracted from medical records. Retinal imaging was extracted from an in-house database. The main outcome measurements were retinal imaging and electroretinography (ERG) and clinical findings, including age of onset, symptoms, best-corrected visual acuity (BCVA), outer nuclear layer (ONL) thickness, ellipsoid zone width (EZW), and hyperautofluorescent ring area. Thirty-one patients were identified, harboring 40 variants in CDH23 (10 being novel). The mean (range, ±SD) age of symptom onset was 10.1years (range = 1-18, SD = ±4.1). The most common visual symptoms at presentation were nyctalopia (93.5%) and peripheral vision difficulties (61.3%). The mean BCVA at baseline was 0.25 ± 0.22 in the right eyes and 0.35 ± 0.58 LogMAR in the left eyes. The mean annual loss rate in BCVA was 0.018 LogMAR/year over a mean follow-up of 9.5years. Individuals harboring the c.5237G>A p.(Arg1746Gln) allele had retinitis pigmentosa (RP) sparing the superior retina. Seventy-seven percent of patients had hyperautofluorescent rings in fundus autofluorescence. Full-field and pattern ERGs indicated moderate-severe rod-cone or photoreceptor dysfunction with relative sparing of macular function in most patients tested. Optical coherence tomography (OCT) revealed intraretinal cysts in the transfoveal B-scan of 13 individuals (43.3%). The rate of EZW and ONL thickness loss was mild and suggestive of a wide window of macular preservation. Despite the early onset of symptoms, USH1D has a slowly progressive phenotype. There is high interocular symmetry across all parameters, making it an attractive target for novel therapies.

Fractal phototherapy: impact on the structure and function of the retina of rabbits with modelled retinal pigment epithelium atrophy

It is believed that in degenerative diseases of the retina, photostimulation by fractal dynamics signals activates neuroplasticity, thereby increasing the efficiency of visual rehabilitation. Previously, we showed a positive effect of fractal phototherapy (FF) on the electroretinogram (ERG) of healthy rabbits and demonstrated the safety of long-term photostimulation courses for the retina. The purpose of this work is to study the effect of FF on the functional activity and morphology of the retina in rabbits with a model of retinal pathology. Material and methods. We modelled an atrophy of retinal pigment epithelium (RPE) on both eyes of 50 rabbits. 30 days after the administration of bevacizumab, the animals were divided into two groups of 25 animals each. In the main group, photostimulation was performed using a device for FF, while in the control group incandescent lamps were used that create radiation of constant intensity. In both groups, 20-minute binocular light stimulation sessions were performed daily, five times a week. ERG and optical coherence tomography of the retina were performed before and after courses of treatment which lasted 1 week, 1 and 3 months. Results. Long-term courses of FF were shown to be safe for the morphology of the retina of animals with the RPE atrophy model. In all periods of observation, biochemical studies revealed no statistically significant changes in the content of norepinephrine and dopamine in the tear as compared with baseline values. In the main group, a slight positive effect of FF on rod and cone ERG was found after 5 FF sessions, while a significant increase in the amplitude of the transient and steady-state pattern-ERG (PERG), most pronounced after a 1-month FF course, was observed. Conclusions. A positive effect of FF on the functional activity of retinal ganglion cells (RGC) may suggest that prescribing a course of FF lasting up to 1 month (20 sessions) in diseases accompanied by a pathology of RGC is advisable, whereas for patients with a pathology of the macular region, such as AMD, an effective improvement in the activity of photoreceptors and bipolar cells could probably be achieved through a 1-week course of FF, conducted under the control of electroretinography.

Mechanisms contributing to inhibition of retinal ganglion cell death by cell permeable peptain-1 under glaucomatous stress

This study assesses the neuroprotective potential of CPP-P1, a conjugate of an anti-apoptotic peptain-1 (P1) and a cell-penetrating peptide (CPP) in in vitro, in vivo, and ex vivo glaucoma models. Primary retinal ganglion cells (RGCs) were subjected to either neurotrophic factor (NF) deprivation for 48 h or endothelin-3 (ET-3) treatment for 24 h and received either CPP-P1 or vehicle. RGC survival was analyzed using a Live/Dead assay. Axotomized human retinal explants were treated with CPP-P1 or vehicle for seven days, stained with RGC marker RBPMS, and RGC survival was analyzed. Brown Norway (BN) rats with elevated intraocular pressure (IOP) received weekly intravitreal injections of CPP-P1 or vehicle for six weeks. RGC function was evaluated using a pattern electroretinogram (PERG). RGC and axonal damage were also assessed. RGCs from ocular hypertensive rats treated with CPP-P1 or vehicle for seven days were isolated for transcriptomic analysis. RGCs subjected to 48 h of NF deprivation were used for qPCR target confirmation. NF deprivation led to a significant loss of RGCs, which was markedly reduced by CPP-P1 treatment. CPP-P1 also decreased ET-3-mediated RGC death. In ex vivo human retinal explants, CPP-P1 decreased RGC loss. IOP elevation resulted in significant RGC loss in mid-peripheral and peripheral retinas compared to that in naive rats, which was significantly reduced by CPP-P1 treatment. PERG amplitude decline in IOP-elevated rats was mitigated by CPP-P1 treatment. Following IOP elevation in BN rats, the transcriptomic analysis showed over 6,000 differentially expressed genes in the CPP-P1 group compared to the vehicle-treated group. Upregulated pathways included CREB signaling and synaptogenesis. A significant increase in Creb1 mRNA and elevated phosphorylated Creb were observed in CPP-P1-treated RGCs. Our study showed that CPP-P1 is neuroprotective through CREB signaling enhancement in several settings that mimic glaucomatous conditions. The findings from this study are significant as they address the pressing need for the development of efficacious therapeutic strategies to maintain RGC viability and functionality associated with glaucoma.

Caspase-8-mediated inflammation but not apoptosis drives death of retinal ganglion cells and loss of visual function in glaucomaa.

Glaucoma is a complex multifactorial disease where apoptosis and inflammation represent two key pathogenic mechanisms. However, the relative contribution of apoptosis versus inflammation in axon degeneration and death of retinal ganglion cells (RGCs) is not well understood. In glaucoma, caspase-8 is linked to RGC apoptosis, as well as glial activation and neuroinflammation. To uncouple these two pathways and determine the extent to which caspase-8-mediated inflammation and/or apoptosis contributes to the death of RGCs, we used the caspase-8 D387A mutant mouse (Casp8 DA/DA ) in which a point mutation in the auto-cleavage site blocks caspase-8-mediated apoptosis but does not block caspase-8-mediated inflammation. Intracameral injection of magnetic microbeads was used to elevate the intraocular pressure (IOP) in wild-type, Fas deficient Faslpr, and Casp8 DA/DA mice. IOP was monitored by rebound tonometry. Two weeks post microbead injection, retinas were collected for microglia activation analysis. Five weeks post microbead injection, visual acuity and RGC function were assessed by optometer reflex (OMR) and pattern electroretinogram (pERG), respectively. Retina and optic nerves were processed for RGC and axon quantification. Two- and five-weeks post microbead injection, expression of the necrosis marker, RIPK3, was assessed by qPCR. Wild-type, Faslpr, and Casp8 DA/DA mice showed similar IOP elevation as compared to saline controls. A significant reduction in both visual acuity and pERG that correlated with a significant loss of RGCs and axons was observed in wild-type but not in Faslpr mice. The Casp8 DA/DA mice displayed a significant reduction in visual acuity and pERG amplitude and loss of RGCs and axons similar to that in wild-type mice. Immunostaining revealed equal numbers of activated microglia, double positive for P2ry12 and IB4, in the retinas from microbead-injected wild-type and Casp8 DA/DA mutant mice. qPCR analysis revealed no induction of RIPK3 in wild-type or Casp8 DA/DA mice at two- or five-weeks post microbead injection. Our results demonstrate that caspase-8-mediated extrinsic apoptosis is not involved in the death of RGCs in the microbead-induced mouse model of glaucoma implicating caspase-8-mediated inflammation, but not apoptosis, as the driving force in glaucoma progression. Taken together, these results identify the caspase-8-mediated inflammatory pathway as a potential target for neuroprotection in glaucoma.

Reduced contrast sensitivity, pattern electroretinogram ratio, and diminished a-wave amplitude in patients with major depressive disorder.

The electroretinogram (ERG), a non-invasive electrophysiological tool used in ophthalmology, is increasingly applied to investigate neural correlates of depression. The present study aimed to reconsider previous findings in major depressive disorder (MDD) reporting (1) a diminished contrast sensitivity and (2) a reduced patten ERG (PERG) amplitude ratio, and additionally, to assess (3) the photopic negative response (PhNR) from the flash ERG (fERG), with the RETeval® device, a more practical option for clinical routine use. We examined 30 patients with a MDD and 42 healthy controls (HC), assessing individual contrast sensitivity thresholds with an optotype-based contrast test. Moreover, we compared the PERG ratio, an established method for early glaucoma detection, between both groups. The handheld ERG device was used to measure amplitudes and peak times of the fERG components including a-wave, b-wave and PhNR in both MDD patients and HCs. MDD patients exhibited diminished contrast sensitivity together with a reduced PERG ratio, compared to HC. With the handheld ERG device, we found reduced a-wave amplitudes in MDD, whereas no significant differences were observed in the fERG b-wave or PhNR between patients and controls. The reduced contrast sensitivity and PERG ratio in MDD patients supports the hypothesis that depression is associated with altered visual processing. The findings underscore the PERG's potential as a possible objective marker for depression. The reduced a-wave amplitude recorded with the RETeval® system in MDD patients might open new avenues for using handheld ERG devices as simplified approaches for advancing depression research compared to the PERG.

IC100, a humanized therapeutic monoclonal anti-ASC antibody alleviates oxygen-induced retinopathy in mice

BackgroundRetinopathy of prematurity (ROP), which often presents with bronchopulmonary dysplasia (BPD), is among the most common morbidities affecting extremely premature infants and is a leading cause of severe vision impairment in children worldwide. Activations of the inflammasome cascade and microglia have been implicated in playing a role in the development of both ROP and BPD. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) is pivotal in inflammasome assembly. Utilizing mouse models of both oxygen-induced retinopathy (OIR) and BPD, this study was designed to test the hypothesis that hyperoxia induces ASC speck formation, which leads to microglial activation and retinopathy, and that inhibition of ASC speck formation by a humanized monoclonal antibody, IC100, directed against ASC, will ameliorate microglial activation and abnormal retinal vascular formation.MethodsWe first tested ASC speck formation in the retina of ASC-citrine reporter mice expressing ASC fusion protein with a C-terminal citrine (fluorescent GFP isoform) using a BPD model that causes both lung and eye injury by exposing newborn mice to room air (RA) or 85% O2 from postnatal day (P) 1 to P14. The retinas were dissected on P14 and retinal flat mounts were used to detect vascular endothelium with AF-594-conjugated isolectin B4 (IB4) and citrine-tagged ASC specks. To assess the effects of IC100 on an OIR model, newborn ASC citrine reporter mice and wildtype mice (C57BL/6 J) were exposed to RA from P1 to P6, then 75% O2 from P7 to P11, and then to RA from P12 to P18. At P12 mice were randomized to the following groups: RA with placebo PBS (RA-PBS), O2 with PBS (O2-PBS), O2 + IC100 intravitreal injection (O2-IC100-IVT), and O2 + IC100 intraperitoneal injection (O2-IC100-IP). Retinal vascularization was evaluated by flat mount staining with IB4. Microglial activation was detected by immunofluorescence staining for allograft inflammatory factor 1 (AIF-1) and CD206. Retinal structure was analyzed on H&E-stained sections, and function was analyzed by pattern electroretinography (PERG). RNA-sequencing (RNA-seq) of the retinas was performed to determine the transcriptional effects of IC100 treatment in OIR.ResultsASC specks were significantly increased in the retinas by hyperoxia exposure and colocalized with the abnormal vasculature in both BPD and OIR models, and this was associated with increased microglial activation. Treatment with IC100-IVT or IC100-IP significantly reduced vaso-obliteration and intravitreal neovascularization. IC100-IVT treatment also reduced retinal microglial activation, restored retinal structure, and improved retinal function. RNA-seq showed that IC100 treatment corrected the induction of genes associated with angiogenesis, leukocyte migration, and VEGF signaling caused by O2. IC100 also corrected the suppression of genes associated with cell junction assembly, neuron projection, and neuron recognition caused by O2.ConclusionThese data demonstrate the crucial role of ASC in the pathogenesis of OIR and the efficacy of a humanized therapeutic anti-ASC antibody in treating OIR mice. Thus, this anti-ASC antibody may potentially be considered in diseases associated with oxygen stresses and retinopathy, such as ROP.

Evaluation of Structural and Functional Retinal Changes in Children With Intermittent Exotropia Versus Healthy Children.

To detect structural and functional changes in children with intermittent exotropia using optical coherence tomography, pattern electroretinography (ERG), and multifocal ERG. The study included 26 patients with intermittent exotropia and 26 healthy individuals matched for age and sex with a mean age of 9.23 and 11.20 years in the intermittent exotropia and control groups, respectively (P = .310). All patients underwent full ophthalmic examination including measurement of the angle of strabismus at near and far, and assessment of the macula and optic nerve using optical coherence tomography, pattern ERG, and multifocal ERG. All patients had 6/6 best corrected visual acuity with no fixation preference. A significantly prolonged P and N wave latency was found in all measured rings of multifocal ERG of patients with intermittent exotropia, P wave amplitude was lower in rings 1 and 5, and N wave amplitude was lower in rings 1 and 2. Regarding pattern ERG, the amplitude of P50 wave was lower and N95 latency was prolonged in the intermittent exotropia group. The upper and lower ganglion cell complex and the superior retinal nerve fiber layer were significantly thinner in the intermittent exotropia group compared to controls. Children with intermittent exotropia without any associated amblyopia or refractive error showed a subnormal pattern and multifocal ERG response in addition to a thinner ganglion cell layer and retinal nerve fiber layer compared to normal controls. This signifies that subtle structural and functional retinal changes are found in patients with intermittent exotropia. [J Pediatr Ophthalmol Strabismus. 20XX;X(X):XXX-XXX.].

Bilateral Pattern Electroretinogram Abnormalities in Patients with Herpes Zoster Keratitis and Conjunctivitis.

Herpes zoster ophthalmicus (HZO) results from the reactivation of varicella zoster virus (VZV) in the ophthalmic branch of the trigeminal nerve. The inflammation caused by VZV involves multiple tissues in the eyes. Our goal is to evaluate pattern electroretinogram (PERG) changes and their relationship with corneal sub-basal nerve changes in patients with HZO. Twenty-two patients with herpes zoster keratitis or conjunctivitis and 20 healthy volunteers were recruited for this cross-sectional study. A PERG test was performed on both eyes of HZO patients and one eye of the healthy controls. In vivo confocal microscopy (IVCM) was also performed on both eyes of the HZO patients to detect corneal nerve damage. Our results showed changes in the PERG parameters in both eyes of HZO patients compared to the healthy controls. Affected eyes showed delayed N95 peak time and decreased P50 and N95 amplitude compared to the unaffected eyes (p < 0.05, respectively). Both affected and unaffected eyes in HZO patients showed delayed P50 peak time and decreased N95 amplitude (p < 0.05, respectively) compared to controls. In HZO patients, no significant differences in each PERG parameter were found between eyes with and without corneal lesions or between eyes with and without increased Langham's cells in the corneal epithelial sub-basal layer. The IVCM images showed decreased total nerve length and number at the sub-basal layer of the epithelial cornea in affected eyes compared to unaffected eyes (p < 0.05). No significant correlation was found between total nerve length and PERG changes. Our results showed that VZV-affected eyes without central cornea involvement displayed reduced N95 amplitude and prolonged P50 peak time in bilateral eyes compared to the healthy controls. Larger studies are needed to further explore the effect of HZO on the electrophysiological response of the eye and the posterior segment.