Gradient conducting polymer surfaces with netrin-1-conjugation promote axon guidance and neuron transmission of human iPSC-derived retinal ganglion cells.

Major advances have been made in utilizing human-induced pluripotent stem cells (hiPSCs) for regenerative medicine. Nevertheless, the delivery and integration of hiPSCs into target tissues remain significant challenges, particularly in the context of retinal ganglion cell (RGC) restoration. In this study, we introduce a promising avenue for providing directional guidance to regenerated cells in the retina. First, we developed a technique for construction of gradient interfaces based on functionalized conductive polymers, which could be applied with various functionalized ehthylenedioxythiophene (EDOT) monomers. Using a tree-shaped channel encapsulated with a thin PDMS and a specially designed electrochemical chamber, gradient flow generation could be converted into a functionalized-PEDOT gradient film by cyclic voltammetry. The characteristics of the successfully fabricated gradient flow and surface were analyzed using fluorescent labels, time of flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS). Remarkably, hiPSC-RGCs seeded on PEDOT exhibited improvements in neurite outgrowth, axon guidance and neuronal electrophysiology measurements. These results suggest that our novel gradient PEDOT may be used with hiPSC-based technologies as a potential biomedical engineering scaffold for functional restoration of RGCs in retinal degenerative diseases and optic neuropathies.

Recognizing Leber's Hereditary Optic Neuropathy to avoid delayed diagnosis and misdiagnosis.

Leber's Hereditary Optic Neuropathy (LHON) is a maternally inherited optic nerve disease primarily caused by mutations in mitochondrial DNA (mtDNA). The peak of onset is typically between 15 and 30 years, but variability exists. Misdiagnosis, often as inflammatory optic neuritis, delays treatment, compounded by challenges in timely genetic diagnosis. Given the availability of a specific treatment for LHON, its early diagnosis is imperative to ensure therapeutic appropriateness. This work gives an updated guidance about LHON differential diagnosis to clinicians dealing also with multiple sclerosi and neuromyelitis optica spectrtum disorders-related optic neuritis. LHON diagnosis relies on clinical signs and paraclinical evaluations. Differential diagnosis in the acute phase primarily involves distinguishing inflammatory optic neuropathies, considering clinical clues such as ocular pain, fundus appearance and visual recovery. Imaging analysis obtained with Optical Coherence Tomography (OCT) assists clinicians in early recognition of LHON and help avoiding misdiagnosis. Genetic testing for the three most common LHON mutations is recommended initially, followed by comprehensive mtDNA sequencing if suspicion persists despite negative results. We present and discuss crucial strategies for accurate diagnosis and management of LHON cases.

Hypoxia-mediated rescue of retinal ganglion cells deficient in mitochondrial complex I is independent of the hypoxia-inducible factor pathway.

Continuous exposure to environmental hypoxia (11% O2) has been shown to markedly slow the progressive degeneration of retinal ganglion cells (RGCs) in a mouse model of mitochondrial optic neuropathy with RGC-specific deletion of the key mitochondrial complex I accessory subunit ndufs4. As a first step toward identifying the therapeutic mechanism of hypoxia in this model, we conducted a series of experiments to investigate the role of the hypoxia-inducible factor (HIF) regulatory pathway in RGC neuroprotection. Vglut2-Cre; ndufs4loxP/loxP mice were crossed with strains bearing floxed alleles of the negative HIF regulatory vhl or of the two major HIF α-subunit isoforms, Hif1α and Hif2α. Deletion of vhl within ndufs4-deficient RGCs failed to prevent RGC degeneration under normoxia, indicating that HIF activation is not sufficient to achieve RGC rescue. Furthermore, the rescue of ndufs4-deficient RGCs by hypoxia remained robust despite genetic inactivation of Hif1α and Hif2α. Our findings demonstrate that the HIF pathway is entirely dispensable to the rescue of RGCs by hypoxia. Future efforts to uncover key HIF-independent molecular pathways induced by hypoxia in this mouse model may be of therapeutic relevance to mitochondrial optic neuropathies such as Leber hereditary optic neuropathy.

Comprehensive assessment of glaucoma in patients with high myopia: a systematic review and meta-analysis with a discussion of structural and functional imaging modalities.

PURPOSE: The interplay between myopia and glaucoma has gained attention, with escalating myopia demonstrating a significant association with increased POAG rates, particularly in patients with severe myopia. This systematic review aimed to comprehensively analyze the relationship between myopia and glaucoma, focusing on the structural and functional implications, risk factors, and assessment modalities. Optical coherence tomography (OCT) played a crucial role in this study, particularly in highly myopic populations. METHODS: This study's rigor is underscored by using the PRISMA guidelines, which ensured a meticulous search strategy was employed across multiple databases from 2012 to 2024. The inclusion criteria included individuals aged 18 years or older with high myopia, defined as a spherical equivalent of less than -6.0 diopters or an axial length > 26.0 mm, diagnosed with chronic glaucoma. Various study designs were incorporated, including randomized controlled trials, prospective cohort studies, and observational studies. Quality assessment was performed using the Jadad Scale, and statistical analyses were performed to summarize the study characteristics and outcomes. RESULTS: Of the 350 initial articles, 15 met the inclusion criteria. OCT assessments revealed structural changes such as thinning of the retinal nerve fiber layer preceding functional losses. Meta-analyses demonstrated a heightened risk of POAG with increasing myopia severity, showing a significant nonlinear relationship. This meta-analysis of six studies involving 3040 patients revealed a relationship between myopia and glaucoma (OR = 12.0, 95% CI 10.1-4.7, P < 0.00001). CONCLUSION: This comprehensive analysis consolidates the evidence of the relationship between myopia and glaucoma, emphasizing the pivotal role of OCT and other imaging modalities in early detection and monitoring.

Glaucoma is a significant cause of permanent blindness worldwide. This causes damage to the visual nerve that worsens over time. The primary way to treat open-angle glaucoma and its many causes is to lower eye pressure. Further research is being conducted to determine the relationship between nearsightedness and glaucoma. Increased nearsightedness is significantly linked to higher rates of glaucoma, especially in people with severe nearsightedness. This review aimed to examine the link between myopia and glaucoma in greater depth, focusing on structural and functional effects, risk factors, and assessment methods, especially optical coherence tomography (OCT), in very nearsighted people. We conducted a thorough search of several databases between 2012 and 2024. Individuals aged 18 years or older with myopia greater than six diopters or an axial length greater than 26 mm and a diagnosis of chronic glaucoma were eligible. Randomized controlled trials, prospective cohort studies, and observational studies were some of the methods used in this study. The quality of the work and statistical methods were used to summarize the features and results of the study. Of the 350 articles initially published, only 15 met the inclusion criteria. These studies mostly used different optical tomography tests to detect structural changes, such as ocular nerve fiber layer damage, before functional loss. According to meta-analyses, the risk of chronic glaucoma increases as myopia worsens, indicating a solid nonlinear relationship. Myopia and glaucoma are linked, demonstrating the importance of thorough evaluation. Severe myopia is strongly associated with damage to the visual nerve. Over the past few years, optical tomography has become a vital imaging tool for identifying early damage to the optic nerve. However, further research is needed on the sex-related tendencies of glaucoma patients. This study provides data that reveal a link between nearsightedness and glaucoma, highlighting the importance of optical tomography and other imaging techniques for early detection and monitoring. To better manage glaucoma in highly myopic individuals, we need to understand how the severity of myopia, changes in structure, and changes in function affect each other.

The influence of polyacrylamide gel substrate elasticity on primary cultures of rat retinal ganglion cells.

In vitro primary cell culture models of retinal ganglion cells (RGC) are widely used to study pathomechanisms of diseases such as glaucoma. The biomechanic interaction with the culture substrate is known to influence core cellular functions. RGC cultures, however, are usually grown on rigid plastic or glass substrates. We hypothesized that soft polyacrylamide gel substrates may alter survival and neurite outgrowth of primary cultured RGC. Primary retinal cultures from postnatal (day 1-6) Wistar rats were grown on glass coverslips or polyacrylamide (PA) gel substrate with different Young's elastic moduli (0.75, 10 or 30 kPa). Substrates were coated with Poly-l-lysine and / or laminin. RGC were immunostained with anti-beta-III-tubulin. Total neurite length, growth cone morphology, RGC density, mitochondrial morphology and transport as well as pro-survival pathways (Erk1/2, Akt, CREB) were assessed. PA gel substrates of E = 10 kPa significantly increased the total neurite length by factor 1.5 compared to glass (p = 0.02). The growth cone area was significantly larger by factor 5.3 on 30 kPa gels (p = 0.01). The presence of a substrate coating was more important for neurite outgrowth and RGC survival on PA gels (poly-l-lysine > laminin) than on glass. Neither mitochondrial morphology and motility nor the activation of pro-survival pathways significantly differed between the four substrates. PA gel substrates significantly enhanced RGC neurite outgrowth. The signaling cascades mediating this effect remain to be determined.

Review: Neuroprotective Nanocarriers in Glaucoma.

Glaucoma stands as a primary cause of irreversible blindness globally, characterized by the progressive dysfunction and loss of retinal ganglion cells (RGCs). While current treatments primarily focus on controlling intraocular pressure (IOP), many patients continue to experience vision loss. Therefore, the research focus has shifted to therapeutic targets aimed at preventing or delaying RGC death and optic nerve degeneration to slow or halt disease progression. Traditional ocular drug administration, such as eye drops or oral medications, face significant challenges due to the eye's unique structural and physiological barriers, which limit effective drug delivery. Invasive methods like intravitreal injections can cause side effects such as bleeding, inflammation, and infection, making non-invasive delivery methods with high bioavailability very desirable. Nanotechnology presents a promising approach to addressing these limitations in glaucoma treatment. This review summarizes current approaches involving neuroprotective drugs combined with nanocarriers, and their impact for future use.

Retinal ganglion cell vulnerability to pathogenic tau in Alzheimer's disease.

Accumulation of pathological tau isoforms, especially hyperphosphorylated tau at serine 396 (pS396-tau) and tau oligomers, has been demonstrated in the retinas of patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Previous studies have noted a decrease in retinal ganglion cells (RGCs) in AD patients, but the presence and impact of pathological tau isoforms in RGCs and RGC integrity, particularly in early AD stages, have not been explored. To investigate this, we examined retinal superior temporal cross-sections from 25 patients with MCI (due to AD) or AD dementia and 16 cognitively normal (CN) controls, matched for age and gender. We utilized the RGC marker ribonucleic acid binding protein with multiple splicing (RBPMS) and Nissl staining to assess neuronal density in the ganglion cell layer (GCL). Our study found that hypertrophic RGCs containing pS396-tau and T22-positive tau oligomers were more frequently observed in MCI and AD patients compared to CN subjects. Quantitative analyses indicated a decline in RGC integrity, with 46-55% and 55-56% reductions of RBPMS+ RGCs (P<0.01) and Nissl+ GCL neurons (P<0.01-0.001), respectively, in MCI and AD patients. This decrease in RGC count was accompanied by increases in necroptotic-like morphology and the cleaved caspase-3 apoptotic marker in RGCs of AD patients. Furthermore, there was a 2.1 to 3.1-fold increase (P<0.05-0.0001) in pS396-tau-laden RGCs in MCI and AD patients, with a greater abundance observed in individuals with higher Braak stages (V-VI), more severe clinical dementia ratings (CDR=3), and lower mini-mental state examination (MMSE) scores. Strong correlations were noted between the decline in RGCs and the total amount of retinal pS396-tau and pS396-tau+ RGCs, with pS396-tau+ RGC counts correlating significantly with brain neurofibrillary tangle scores (r= 0.71, P= 0.0001), Braak stage (r= 0.65, P= 0.0009), and MMSE scores (r= -0.76, P= 0.0004). These findings suggest that retinal tauopathy, characterized by pS396-tau and oligomeric tau in hypertrophic RGCs, is associated with and may contribute to RGC degeneration in AD. Future research should validate these findings in larger cohorts and explore noninvasive retinal imaging techniques that target tau pathology in RGCs to improve AD detection and monitor disease progression.

Effects of elevated intraocular pressure on alpha ganglion cells in experimental glaucoma mice.

Glaucoma is a leading cause of blindness worldwide and glaucoma patients exhibit an early diffuse loss of retinal sensitivity followed by focal loss of RGCs. Combining some previous published results and some new data, this paper provides our current view on how high IOP (H-IOP) affects the light response sensitivity of a subset of RGCs, the alpha-ganglion cells (αGCs), as well as their presynaptic bipolar cells (DBCs and HBCs) and A2 amacrine cells (AIIACs) in dark-adapted mouse retinas. Our data demonstrate that H-IOP in experimental glaucoma mice significantly decreases light-evoked spike response sensitivity of sONαGCs and sOFFαGCs (i.e., raises thresholds by 1.5-2.5 log units), but not that of the tONαGCs and tOFFαGCs. The sensitivity loss in sONαGCs and sOFFαGCs is mediated by a H-IOP induced suppression of AIIAC response which is caused by a decrease of transmission efficacy of the DBCR→AIIAC synapse. We also provide evidence supporting the hypothesis that BK channels in the A17AC→DBCR feedback synapse are the H-IOP sensor that regulates the DBCR→AIIAC synaptic efficacy, as BK channel blocker IBTX mimics the action of H-IOP. Our results provide useful information for designing strategies for early detection and possible treatments of glaucoma as physiological changes occur before irreversible structural damage.

Efficient digital design of ganglion cells in the retinal pathway.

Spiking networks, the third generation of neural networks, are presented as low-power consumption machines with higher cognitive ability, one of the main concerns in intelligence machines. In fact, neuromorphic systems are hardware implementations of spiking networks with minimum resource, area, and power consumption while preserve maximum working frequency. Here, the focus is on the digital implementation of Retinal Ganglion Cell (RGC) based on the linear approximation of non-linear terms which is called Linear Retinal Ganglion Cell (LRGC). The low-cost hardware design of biological cells is acceptable when the digital model of the cell has the same phase and time domain behavior as the original model and follows the dynamic behavior of the original model accurately, which is discussed and confirmed with different analyzes in this paper. The low-cost hardware design of biological cells allows the optimal implementation of a neural population on the hardware, provided that the collective behavior of the digital model matches the original model which is approved by the large-scale simulation of RGC and LRGC models. Cognitive processes are performed in the nervous system at a very low cost, which neuromorphic systems are trying to achieve this important. In this regard, the behavior of RGC and LRGC models in the reconstruction of the image through the retina pathway was examined and a high agreement between the performance of the two models was achieved. Finally, the high functional compatibility of RGC, LRGC models proves that the proposed model is a good candidate of the main model in neuromorphic systems with low hardware cost.

Evaluation of nerve fiber layer and ganglion cell complex changes in patients with migraine using optical coherence tomography.

Purpose: To analyze changes in peripapillary retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness in migraine patients with and without aura compared to healthy controls and to identify factors influencing the occurrence of these anomalies. Methods: This is a cross-sectional case-control study including migraine patients and control subjects. All patients and controls underwent a complete ophthalmological examination, RNFL and GCC thickness measurements using a spectral domain-OCT device.The duration of migraine, the frequency and duration of migraine attacks, the migraine disability assessment (MIDAS) and migraine severity scale (MIGSEV) questionnaire scores were recorded. Results: One hundred and twenty eyes from 60 patients (60 eyes in the migraine without aura (MWoA) group and 60 eyes in the migraine with aura (MWA) group) were included. Control group included 30 age and gender matched healthy participants (60 eyes). OCT revealed that RNFL and GCC thickness were significantly reduced in the migraine without aura (MWoA) and in the migraine with aura (MWA) groups compared to the control group and in the migraine with aura (MWA) group compared to the migraine without aura (MWoA) group. Prolonged disease duration was associated to decreased GCC thickness. RNFL and GCC thickness were correlated to disease severity, attack frequency and duration. In the multivariate study, duration of migraine and attack frequency were the main determinant factors of nasal GCC thickness. Disease severity was the main determinant of RNFL and GCC thickness, with the exception of the nasal sector. Conclusion: Our study emphasize the significant impact of both types of migraine on retinal structures. OCT would serve as a valuable biomarker in migraine.

Assessment of OCT and Angio-OCT Parameters in Keratoconus Patients with and without Penetrating Keratoplasty.

Background/Objectives: Keratoconus (KC) is a bilateral eye disease characterized by corneal thinning and cone-like deformation, leading to visual impairment. This study evaluated the radial peripapillary capillaries (RPCs) in keratoconus patients with and without penetrating keratoplasty (PKP) using OCT and angio-OCT, comparing the results to a control group. Methods: This retrospective study included 149 eyes, 97 from patients who underwent PKP between January 2018 and February 2023 and 52 from patients who did not undergo PKP. The control group comprised 72 patients (144 eyes) who were healthy volunteers. Measurements included the best corrected visual acuity (BCVA), the intraocular pressure (IOP), slit-lamp biomicroscopy, a fundus examination, and corneal topography, as well as OCT and angio-OCT assessments of the RPCs, retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), and central retinal thickness (CRT). Statistical analyses were performed using Student's t-test and Pearson's correlation coefficient. Results: The RNFL was significantly thinner in KC eyes after PKP compared to control eyes (p < 0.001), and the CRT was significantly thicker in KC eyes after PKP compared to control eyes (p = 0.003). However, the GCC was similar across the groups (p = 0.0885). Additionally, RPCs inside the disc were significantly reduced in KC eyes after PKP compared to control eyes (p < 0.0001). A significant positive correlation was found between RPC whole vessel density and RNFL thickness as measured via angio-OCT (r = 0.308, p < 0.0001). Conclusions: This study found that the RPC density inside the disc is significantly reduced in keratoconus patients after penetrating keratoplasty, highlighting RPCs inside the disc as a potential diagnostic tool for further assessment of keratoconus.

Impact of Intra-Retinal Fluids on Changes in Retinal Ganglion Cell and Nerve Fiber Layers in Neovascular AMD under Anti-VEGF Therapy.

Purpose: To investigate the influence of intraretinal fluid (IRF) on change in retinal nerve fiber layer (RNFL) and retinal ganglion cell layer (RGCL) and thickness in patients with naive neovascular AMD under anti-VEGF treatment. Design: post hoc analysis. Methods: 97 eyes of 83 patients on continuous therapy with intravitreal anti-vascular endothelial growth factors (anti-VEGF) and a follow-up of 24 months were included. RGCL and RNFL thickness in the perifoveal (-O), parafoveal (PF), and nasal areas and number of injections (IVI) were recorded before the first IVI as well as 1 and 2 years after initiating treatment and compared longitudinally and between groups with and without IRF. Results: The group with IRF at baseline had a higher RNFL thickness at baseline and showed a significant reduction in RNFL-PF between baseline and first and second follow-ups (p < 0.001) but not between first and second follow-ups. The group without IRF showed no significant reduction in RNFL over time. The presence of IRF was not associated with a reduction in RNFL-O or RNFL-nasal. RGCL thickness decreased significantly in both groups with and without IRF after 2 years. Number of IVIs showed no significant correlation to RNFL or RGCL after stratification for the presence of IRF. Conclusions: The presence of IRF has a significant influence on RNFL thickness at baseline as well as on its changes over time during anti-VEGF therapy. The preoperative presence of IRF should be considered when comparing changes in RNFL thickness after IVI.

Interocular Symmetry and Intermachine Reproducibility of Optic Disc and Macular Parameters Measured by Two Different Models of Optical Coherence Tomography.

Purpose: To compare the interocular symmetry and investigate the intermachine reproducibility of optic disc and macular data measured by spectral-domain high-definition optical coherence tomography (HD-OCT) Cirrus HD-OCT 4000 and HD-OCT 5000 from healthy subjects. Patients and Methods: Forty-three volunteers were examined with both HD-OCT 4000 and HD-OCT 5000 at the same visit. Optic nerve head (ONH) and macular data were acquired using ONH Cube 200×200 scans and macular volume cube 512×128 scans, respectively. Results: The average age of the participants was 33 ± 8.6 years. Interocular OCT parameters of ONH and macula showed a high correlation between the right and left eyes regardless of HD-OCT models, displaying a low coefficient of variation (CV). However, the average retinal nerve fiber layer (RNFL) was thicker (96.67±11.19µm vs 95.3±10.89µm, p<0.01), and the average central subfield thickness (261.51±17.45µm vs 262.51±17.39 µm, p<0.01) and cube average thickness (283.91± 13.59µm vs 286.55±13.09µm, p<0.05) were thinner when measured by Cirrus 4000 compared to 5000. Intermachine reproducibility and reliability of RNFL and macular parameters exhibited a high intraclass correlation coefficient (ICC) (0.985) and low CV (2.4%). Ganglion cell-inner plexiform layer (GCIPL) measured by two OCT models showed similar values with an average thickness of 85 µm and had high intermachine reproducibility with high ICC (0.993) and low CV (1.2%). Conclusion: High interocular symmetry was observed across both HD-OCT models. Intermachine reproducibility for RNFL and all macular parameters was also high. GCIPL showed minimal intermachine differences with high reproducibility and reliability. Thus, the results imply that GCIPL values measured by two Cirrus OCT models may be used interchangeably.

Environmental Light Controls the Daily Organization of Breathing by Activating Brn3b-expressing Intrinsically Photosensitive Retinal Ganglion Cells in Mice.

Rhythmic, daily fluctuations in minute ventilation are controlled by the endogenous circadian clock located in the suprachiasmatic nucleus (SCN). While light serves as a potent synchronizer for the SCN, it also influences physiology and behavior by activating Brn3b-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs). It is currently unclear the extent to which the external light environment shapes daily ventilatory patterns independent of the SCN. To determine the relative influence of environmental light versus circadian timing on the organization of daily rhythms in minute ventilation, we used whole-body plethysmography to measure the breathing of mice housed on a non-entraining T28 cycle (14 h light:14 h dark). Using this protocol, we found that minute ventilation exhibits a ~28-h rhythm with a peak at dark onset that coincides with the light:dark cycle and the animals' locomotor activity. To determine if this 28-h rhythm in minute ventilation was mediated by Brn3b-expressing ipRGCs, we measured the breathing of Brn3bDTA mice housed under the T28 cycle. Brn3bDTA mice lack the Brn3b-expressing ipRGCs that project to many non-SCN brain regions. We found that despite rhythmic light cues occurring on a 28-h basis, Brn3bDTA mice exhibited 24-h rhythms in minute ventilation, locomotor activity, and core body temperature consistent with organization by the SCN. The 24-h minute ventilation rhythm of Brn3bDTA mice was found to be driven predominantly by tidal volume rather than respiratory rate. These data indicate that the external light:dark cycle can directly drive daily patterns in minute ventilation by way of Brn3b-expressing ipRGCs. In addition, these data strongly suggest that the activation of Brn3b-expressing ipRGCs principally organizes daily patterns in breathing and locomotor activity when light:dark cues are presented in opposition to endogenous clock timing.

Evaluation of insomnia effect on ganglion cell complex, middle retina, and choroid.

PURPOSE: Insomnia is a common psychiatric disorder that has oxidative and degenerative effects on the brain. It is thought that the brain's processes affect the retina through their synaptic connections. However, the effects of sleep disorders on the retina and choroid are not fully understood. We aimed to investigate the impact of insomnia on retinal nerve fiber layer (RNFL), central foveal thickness, retinal layers, and choroidal thickness. METHODS: The right eye of 16 healthy controls and 15 patients with insomnia complaints for 3 months, no history of psychiatric drug use, and an Insomnia Severity Index (ISI) score of 15 or higher were included in the study. The retinal layers and RNFL analyses were performed using optical coherence tomography (OCT), and choroidal layers were analyzed using enhanced depth imaging OCT. RESULTS: Nasal and temporal ganglion cell complex thicknesses were significantly lower in patients with insomnia compared to the controls (97 µm vs. 111 µm P = 0.004; 94 µm vs. 105 µm P = 0.012, respectively). A significant negative correlation was detected between the ISI score and global RNFL thickness (rho, P = 0.03) Additionally, pachychoroid-like vascular structures were observed in choroidal images. CONCLUSION: These changes in the retina and the choroid layers due to insomnia may be precursors to retinal degenerative conditions, such as age-related macular degeneration that may occur in the future. Multicenter studies including more patients are needed to demonstrate the importance of quality sleep for eye health.

Progressive Thickening of Retinal Nerve Fiber and Ganglion Cell Complex Layers Following SDM Laser Vision Protection Therapy in Open-Angle Glaucoma.

INTRODUCTION: This work aims to determine the effect on nerve fiber layer (NFL) and ganglion cell complex (GCC) thickness trends in eyes with open-angle glaucoma (OAG) treated with Vision Protection Therapy™ (VPT). METHODS: A retrospective analysis of spectral-domain optical coherence tomography (OCT) measured NFL and GCC thickness trends was performed, excluding eyes with poor-quality scans and principal diagnoses other than OAG. This study compares eyes with OAG managed conventionally with IOP control alone (controls) to eyes managed with the addition of VPT (VPT eyes). The direction (+ or -) and magnitude (microns/year) of the OCT trends were the study endpoints. RESULTS: Seventy-eight control eyes of 40 patients and 61 VPT-treated eyes of 39 patients were included in the study. Positive NFL trends were noted in 5% of control eyes vs. 71% of VPT eyes (p < 0.0001). Positive GCC trends were noted in 8% of control eyes vs. 43% of VPT eyes (p < 0.0001). Mean NFL trends (µm/year) were - 0.692 for controls vs. 0.347 for VPT (p < 0.0001). Mean GCC trends (µm/year) were - 0.554 for controls vs. - 0.148 for VPT (p = 0.0175). CONCLUSIONS: The addition of VPT to the conventional management of OAG resulted in highly significant improvements in NFL and GCC trends, indicating a reversal of key indicators of glaucoma severity and progression.

Etomidate protects retinal ganglion cells from hydrogen peroxide-induced injury via Nrf2/HO-1 pathway.

AIM: To determine whether etomidate (ET) has a protective effect on retinal ganglion cells (RGCs) injured with hydrogen peroxide (H2O2) and to explore the potential mechanism underlying the antioxidative stress effect of ET. METHODS: Cultured RGCs were identified by double immunofluorescent labeling of microtubule-associated protein 2 and Thy1.1. An injury model of H2O2-induced RGCs oxidative stress was established in vitro. Cells were pretreated with different concentrations of ET (1, 5, and 10 µmol/L) for 4h, followed by further exposure to H2O2 at 1000 µmol/L. Cell counting kit 8 and Annexin V/propidium iodide assays were applied to detect the viabilities and apoptosis rates of the RGCs at 12, 24, and 48h after H2O2 stimulation. The levels of nitric oxide, malondialdehyde, and glutathione in culture media were measured at these time points. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot were performed to observe the effects of ET on the messenger RNA and protein expression of inducible nitric oxide synthase (iNOS), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), glutathione peroxidase 1 and the level of conjugated acrolein in RGCs at 12, 24, and 48h after H2O2 stimulation and in the retina at 12h after optic nerve transection (ONT). RESULTS: The applications of 5 and 10 µmol/L of ET significantly increased the viability of RGCs. Results from qRT-PCR indicated a decrease in the expression of iNOS and an increase in the expressions of Nrf2 and HO-1 in ET-pretreated RGCs at 12, 24 and 48h after H2O2 stimulation, as well as in ET-treated retinas at 12h after ONT. Western blot analysis revealed a decrease in the expression of iNOS and levels of conjugated acrolein, along with an increase in the expressions of Nrf2 and HO-1 in ET-pretreated RGCs in vitro and ET-treated retinas in vivo. CONCLUSION: ET is a neuroprotective agent in primary cultured RGCs injured by H2O2. The effect of ET is dose-dependent with the greatest effect being at 10 µmol/L. ET plays an antioxidant role by inhibiting iNOS, up-regulating Nrf2/HO-1, decreasing the production of acrolein, and increasing the scavenge of acrolein.

Crystallin ß-b2 promotes retinal ganglion cell protection in experimental autoimmune uveoretinitis.

Crystallin ßb2 (crybb2) is upregulated in regenerating retinas and in various pathological conditions of the retina, including uveoretinitis. However, the role of crybb2 in this disease is largely unknown. Therefore, we used recombinant crybb2 (rcrybb2) as intravitreal treatment of B10.RIII mice prior to immunization with human interphotoreceptor retinoid-binding protein peptide 161-180 (hIRBPp161-180) in complete Freund's adjuvant (CFA) and concomitant injection of pertussis toxin (PTX) to induce experimental autoimmune uveoretinitis (EAU). In naïve mice, more beta III-tubulin (TUBB3) + and RNA-binding protein with multiple splicing (RBPMS) + cells were found in the ganglion cell layer of the retina than in EAU eyes, suggesting a loss of retinal ganglion cells (RGC) during the development of EAU. At the same time, the number of glial fibrillary acidic protein (GFAP) + cells increased in EAU eyes. RGCs were better protected in EAU eyes treated with rcrybb2, while the number of GFAP+ cells decreased. However, in retinal flatmounts, both retinal ganglion cells and retinal endothelial cells stained positive for TUBB3, indicating that TUBB3 is present in naïve B10.RIII mouse eyes not exclusive to RGCs. A significant decline in the number of RBPMS-positive retinal ganglion cells was observed in retinal flatmounts from EAU retinas in comparison to naïve retinas or EAU retinas with intravitreal rcrybb2 treatment. Whereas no significant decrease in TUBB3 levels was detected using Western blot and RT-qPCR, GFAP level, as a marker for astrocytes, increased in EAU mice compared to naïve mice. Level of Bax and Bcl2 in the retina was altered by treatment, suggesting better cell survival and inhibition of apoptosis. Furthermore, our histologic observations of the eyes showed no change in the incidence and severity of EAU, nor was the immune response affected by intravitreal rcrybb2 treatment. Taken together, these results suggest that intravitreal injection of rcrybb2 reduces retinal RGC death during the course of EAU, independent of local or systemic autoimmune responses. In the future, treating posterior uveitis with rcrybb2 to protect RGCs may offer a promising novel therapeutic strategy.

Microcystic Macular Edema Caused by Non-Glaucomatous Optic Atrophy: A Single-Center, Retrospective, Cohort Study in France.

Optic Atrophy (OA) can be associated with the development of microcystic macular edema (MME) in the perifoveal retinal inner nuclear layer (INL). We aimed here to retrospectively determine the prevalence of MME in patients with non-glaucomatous OA in our tertiary ophthalmology department between 2015 and 2020. We then examined how MME affected the thicknesses of the different retinal layers and the differences in demographic and clinical characteristics between those patients who developed MME and those who did not. A total of 643 eyes (429 patients) were included (mean age 45.9 ± 17.8 years, 52% female). MME developed in 95 (15%) eyes and across all etiologies of OA except for toxic/nutritional causes, but the prevalence of MME varied between the different etiologies. The development of MME was associated with thinning of the ganglion cell layer (11.0 vs. 9.6 µm; p = 0.001) and the retinal nerve fiber layer (10.1 vs. 9.15 µm; p = 0.024), with INL thickening in the 3- and 6-mm diameter areas of the central fovea. Patients developing MME had significantly worse distance best-corrected visual acuity than those not developing MME (0.62 vs. 0.38 logMAR; p = 0.002). Overall, the presence of MME in OA cannot be used to guide the diagnostic work-up of OA.

Spatially Selective Retinal Ganglion Cell Activation Using Low Invasive Extraocular Temporal Interference Stimulation.

Conventional retinal implants involve complex surgical procedures and require invasive implantation. Temporal Interference Stimulation (TIS) has achieved noninvasive and focused stimulation of deep brain regions by delivering high-frequency currents with small frequency differences on multiple electrodes. In this study, we conducted in silico investigations to evaluate extraocular TIS's potential as a novel visual restoration approach. Different from the previously published retinal TIS model, the new model of extraocular TIS incorporated a biophysically detailed retinal ganglion cell (RGC) population, enabling a more accurate simulation of retinal outputs under electrical stimulation. Using this improved model, we made the following major discoveries: (1) the maximum value of TIS envelope electric potential ([Formula: see text] showed a strong correlation with TIS-induced RGC activation; (2) the preferred stimulating/return electrode (SE/RE) locations to achieve focalized TIS were predicted; (3) the performance of extraocular TIS was better than same-frequency sinusoidal stimulation (SSS) in terms of lower RGC threshold and more focused RGC activation; (4) the optimal stimulation parameters to achieve lower threshold and focused activation were identified; and (5) spatial selectivity of TIS could be improved by integrating current steering strategy and reducing electrode size. This study provides insights into the feasibility and effectiveness of a low-invasive stimulation approach in enhancing vision restoration.