Eye and Brain最新文献

Introduction: Repetitive head impacts (RHIs) and visual system dysfunction are often associated. Interventions to prevent or limit visual deficits following RHIs are not well understood. This study examined visual structure and function following exposure to RHIs and the effectiveness of a supplemental intervention of macular pigment carotenoids (MPCs) and omega-3 fatty acids in attenuating visual changes from pre- to post-season in collegiate rugby players. Additionally, blood biomarkers associated with neurodegeneration were examined.

Methods: Optical coherence tomography measured visual structure through ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) thickness. Bioavailability of the supplement was assessed through skin carotenoid concentration (SC). Contrast sensitivity (CS) and critical flicker-fusion frequency (CFF) were used to measure visual function. NF-L, GFAP, Tau, and UCH-L1 concentrations in blood samples were analyzed.

Results: Thirty-one rugby players (15M/16F; 19±1.4 years) were randomly assigned to supplement (n = 15) or placebo (n = 16) groups. Left eye GCC inferior region was thinner at post-season in supplement (102.1±4.4 vs 102.9±4.7 μm; p = 0.002) and placebo groups (101.4±5.3 vs 102.6±5.0 μm, p < 0.001). The supplement group had a higher SC score at post-season versus the placebo group (409.2±76.3 vs 323.4±61.3; p = 0.04). With regards to visual function, CFF approached a significant increase in the supplemental group versus placebo (27.6±1.8 vs 25.7±2.2 Hz, p = 0.08), but there were no differences found between groups in MPOD or CS. NF-L was different at post-season in the placebo (10.05 vs 7.21 pg/mL; p = 0.003) but not the supplement group (7.07 vs 7.78 pg/mL; p = 0.40). Tau was different between groups at pre- (1.2 vs 0.87 pg/mL; p = 0.04) and post-season (1.33 vs 1.01 pg/mL; p = 0.02) with greater concentrations in the supplement group. GFAP and UCH-L1 were not different. One season of collegiate rugby resulted in retinal thinning and increased concentrations of NF-L and Tau. Supplementation with MPCs and omega-3s may be useful in limiting retinal thinning and preventing increases in biomarkers of neurodegeneration.

Dementia and cataract are two of the most prevalent conditions in older adults, together representing a substantial global health burden. Increasing evidence suggests a potential link between cataract and dementia, and this narrative review synthesizes current epidemiological and mechanistic evidence on their association. Recent cohort and case-control studies report a modestly increased risk of dementia in individuals with cataracts, though inconsistencies persist across populations. Mechanistic insights highlight roles for visual impairment and protein aggregation in this association. Importantly, cataract surgery shows a robust, protective effect against incident dementia, potentially via restoration of sensory input and enhanced cognitive engagement. Future studies may examine longitudinal, multi-ethnic cohorts that integrate genetic, imaging, and molecular data to investigate causality and the underlying biological mechanisms. In summary, our narrative review shows that cataract and dementia may be linked through multifactorial pathways, and maintaining visual health, particularly through timely cataract surgery, represents a potentially modifiable factor in dementia prevention strategies.

Purpose: Microgravity-induced headward fluid shifts are one of the mechanisms implicated in spaceflight-associated eye conditions, including intraocular pressure (IOP) and retinal nerve fiber layer (RNFL) thickness changes. In this longitudinal study, we investigated IOP and RNFL thickness changes over time in a mouse model of microgravity-induced headward fluid shifts.

Methods: The study involved 20 adult male B6(Cg)-Tyr ^{c -2J} /J mice, randomly assigned to two groups: the hindlimb unloading (HU) mice, unloaded for 21 days followed by 14 days of release, and control mice kept under the same conditions except HU for 35 days. IOP and RNFL thickness in peripapillary and peripheral rings of right and left eyes were measured before and once a week after HU. Our analysis utilized mixed linear models to compare the estimated marginal means of IOP and RNFL thickness on each day with baseline values for each eye. Post hoc splined mixed linear models with a knot at day 14 were employed to assess the rate of IOP change in each segment.

Results: IOP was significantly elevated in both eyes of the HU mice on day 14 compared to baseline. The splined analysis revealed a bilateral positive rate of IOP change up to day 14, followed by a negative rate of change thereafter. In contrast, control mice displayed no significant differences in IOP at any timepoint. RNFL thicknesses of right eye peripapillary and peripheral rings were reduced after 1 week and 2 weeks, respectively. In contrast, left eye RNFL thickness measurements did not show any significant change compared to baseline.

Conclusion: The HU mouse model displays a distinct ocular phenotype that may be useful for understanding IOP and RNFL changes in microgravity and their relevance to Spaceflight-Associated Neuro-ocular Syndrome.

Idiopathic Intracranial Hypertension (IIH) is characterized by elevated intracranial pressure in the absence of secondary causes. The treatment of IIH entails a combination of lifestyle modifications, medical therapy, and surgical intervention. This article aims to evaluate the role of acetazolamide in the treatment of IIH and identify its mechanism of action, efficacy, and side effect profile. This article also aims to discuss acetazolamide's role in conjunction with other treatment modalities.

Purpose: To investigate the impact of mild visual acuity loss on the Müller-Lyer illusion in adults and evaluate its potential as a clinical indicator for visual-cognitive integration mechanisms.

Methods: Three experiments were conducted. Experiment 1 measured illusion intensity in 49 young adults (25.08 ± 3.38 years) before and after inducing transient visual acuity loss (0.40 logMAR) via Bangerter occlusion foils. Experiment 2 compared 26 cataract patients (65.19 ± 3.87 years) with 59 age-matched controls (63.98 ± 5.57 years). Experiment 3 tracked 14 cataract patients (69.50 ± 6.14 years) pre- and post-surgery. Illusion intensity was quantified using a two-alternative forced-choice task.

Results: Illusion intensity remained stable across conditions: no differences were observed before /after wearing occlusion glasses (4.33% vs 3.75%, p = 0.141), between cataract patients and controls (8.79% vs 8.20%, p = 0.301), or pre-/post-surgery (9.46% vs 9.87%, p = 0.357). However, normally-sighted elderly participants exhibited stronger illusions than young adults (8.20% vs 4.33%, p < 0.001). Multivariate regression confirmed age as the sole predictor of illusion intensity (β = 0.088, p = 0.001), independent of visual acuity.

Conclusion: The intensity of Müller-Lyer illusion in adults is modulated by age but resistant to mild visual acuity loss, implicating its utility in studying visual-cognitive integration.

Background: Over the past few decades, technological advancements have transformed invasive visual prostheses from theoretical concepts into real-world applications. However, functional outcomes remain limited, especially in visual acuity. This review aims to summarize current developments in retinal and cortical prostheses (RCPs) and critically assess the role of artificial intelligence (AI) in advancing these systems.

Purpose: To describe current RCPs and provide a systematic review on image and signal processing algorithms designed for improved clinical outcomes.

Patients and methods: We performed a systematic review of the literature related to AI subserving prosthetic vision, using mainly PubMed, but also, Elicit, a dedicated AI-based reference research assistant. A total of 455 studies were screened on PubMed, of which 23 were retained for inclusion. An additional 5 studies were identified and included through Elicit.

Results: The analysis of current RCPs highlights various limitations affecting the quality of the visual flow provided by current artificial vision. Indeed, the 28 reviewed studies on AI covered two applications for RCPs including extraction of saliency in camera captured images, and consistency between electrical stimulation and perceived phosphenes. A total of 14 out of 28 studies involved the use of artificial neural networks, of which 12 included model training. Evaluation with data from a visual prosthesis was conducted in 7 studies, including 1 that was prospectively assessed with a human RCP. Validation with empirical data from human or animal data was performed in 22 out of 28 studies. Out of these, 15 were validated using simulated prosthetic vision. Finally, out of 22 studies leveraging a mathematical model for phosphenes perception, 14 used a symmetrical oversimplified modeling.

Conclusion: AI algorithms show promise in optimizing prosthetic vision, particularly through enhanced image saliency extraction and stimulation strategies. However, most current studies are based on simulations. Further development and validation in real-world settings, especially through clinical testing with blind patients, are essential to assess their true effectiveness.

Purpose: Evaluate whether optic disc edema results in changes in retinal microcirculation.

Patients and methods: The study group consisted of 11 patients with unilateral optic disc edema (papilledema). The control group consisted of the healthy eyes of the same 11 patients. Patients underwent non-invasive photo-spectrometric retinal oximetry using Oxymap T1 retinal oximeter (Oxymap, Reykjavik, Iceland). In the eyes of these 11 patients, we examined the diameter of the retinal arteries and veins, arterial and venous blood oxygen saturation, and the difference in oxygen saturation between arterioles and venules (A-V difference).

Results: In the papilledema group, the decrease in the retinal arterial diameter was statistically significant (p=0.001). The median diameter of the retinal artery was 11.70 px (IQR 1.47) or after conversion 109.00 µm (IQR 14.00) in the papilledema group and 13.75 px (IQR 1.61) or 128.00 µm (IQR 15.00) in the control group. The increase in the diameter of the retinal veins in the papilledema group was statistically significant (p=0.012), where the median diameter in the papilledema group was 20.88 px (IQR 3.72) or 194.00 µm (IQR 35.00), and in the control group was 18.18 px (IQR 3.60) or 169 µm (IQR 33.00). There was a statistically significant decrease (p<0.001) in the venous saturation in the papilledema group with a median value of 53.16% (IQR 17.38) and 60.02% (IQR 11.98) in the control group. The median of the A-V difference was 51.92 (IQR 15.96) in the papilledema group, resp. 38.49 (IQR 9.75) in the control group and a significant increase in the papilledema group (p<0.001) was reported.

Conclusion: Automatic retinal oximetry demonstrated changes in the retinal microcirculation in patients with optic disc edema.

Purpose: Like motor neurons, retinal ganglion cells (RGCs) have long axons and high metabolic demands, making them vulnerable to disruption of axonal transport. Unlike motor neurons, the RGC axons are accessible to high-resolution non-invasive optical imaging in their intraocular portion. A non-invasive in vivo retinal imaging biomarker can be valuable for amyotrophic lateral sclerosis (ALS) diagnosis and monitoring. We aim to assess the presence of inner retinal pathology in a mouse model of ALS and its possible progression with age.

Methods: Transgenic SOD1G93A mice (n=8, 4M/4F) and age-matched controls (n=8, 4M/4F) underwent in vivo retinal imaging with confocal scanning laser ophthalmoscopy (cSLO) coupled with optical coherence tomography (OCT) at 20 weeks of age. Another group of SOD1G93A mice (n=20, 6M/14F) and age-matched controls (n=20, 6M/14F) underwent longitudinal in vivo retinal imaging with the same device. Each retinal imaging session included infrared reflectance (IR) and blue reflectance (BR) cSLO coupled with OCT. Hyperreflective puncta located in the retinal nerve fiber layer (RNFL) were counted in a blinded fashion in ALS and control mice. The number of puncta at 20 weeks of age in ALS mice was compared with controls using Wilcoxon test. The rates of increase of puncta number were analyzed using a Generalized Linear Mixed-Effect Model (GLMM) for genotype, time, and sex.

Results: IR-cSLO coupled with OCT revealed hyperreflective puncta located in the RNFL of ALS mice. IR-cSLO fundus imaging at the age of 20 weeks showed ALS mice had significantly higher number of puncta compared to controls (2.1±2.3 vs 0.5±0.8; (mean±SD), respectively, p=0.036). GLMM analysis showed both ALS mutation and age were significantly associated with the rate of increase of puncta number (p=0.000232 and p=0.000366, respectively). In addition, female ALS mice had a steeper increase of puncta compared to male ALS mice (0.21±0.04 log number puncta/week vs 0.16±0.04, respectively; p=0.037).

Conclusion: Our findings demonstrate distinct inner retinal nerve fiber layer pathology, detected using cSLO coupled with OCT, which worsens over time. These findings support the potential of retinal imaging as a translationally relevant, non-invasive biomarker for ALS diagnosis or disease monitoring in humans.

The visual system is an integral part of the central nervous system, and visual symptoms often serve as an early manifestation of underlying neurological pathologies. This review synthesizes recent findings on visual dysfunction in various neurodevelopmental and neurodegenerative diseases. These reports emphasize that ophthalmological symptoms are increasingly recognized as part of a broader spectrum of neurological conditions, enhancing their clinical relevance for differential diagnosis and symptom management. Non-invasive, high-resolution ocular imaging techniques can identify retinal pathologies at the subcellular level. Additionally, the non-invasive visual functional assay, electroretinography, can further corroborate findings of retinal pathology. Distinct retinal changes are detectable in the early stages of progressive neurodegenerative diseases, such as Parkinson's disease, and are strongly correlated with cognitive decline in conditions like Huntington's disease, Alzheimer's disease, and Joubert syndrome. These findings highlight the clinical potential of retinal imaging for risk assessment, diagnosis, and monitoring the progression of diseases with insidious onset. Furthermore, this review emphasizes the retina's accessibility as a key component in investigating the underlying pathophysiology of neurological conditions. Additional clinical and basic science research is needed to better understand the distinct and potentially interconnected contributions of the brain and retina to specific visual symptoms. Investigating suitable preclinical mouse models will be vital for developing and refining novel ocular diagnostic markers, which are important for symptom management and the advancement of therapeutic strategies.

Ocular dominance plasticity, the ability of the brain to change sensory eye balance, has traditionally been believed to be extremely limited in adult visual cortex. However, recent studies on short-term monocular deprivation (MD) demonstrate that its presence is prevalent in adult humans, as short-term MD is capable of significantly shifting ocular dominance in favor of the previously deprived eye. Thus, findings over the last 15 years highlight that short-term MD can be a promising alternative treatment for amblyopia, a neurodevelopmental disorder characterized by binocular imbalance. Conventionally, amblyopia has been treated with patching therapy, which shows limited effectiveness in restoring binocularity of adults and is associated with poor compliance rate and high psychosocial distress. Thus, it is an opportune time to explore how short-term MD can be utilized as an alternative treatment option for restoring amblyopic vision, especially individuals who do not respond robustly to standard treatment. This review provides an overview of foundational studies on ocular dominance plasticity in both visually intact and impaired observers. It also evaluates the potential of short-term MD as a treatment for amblyopia and suggests its future research directions, including the integration of multimodal therapeutic strategies that include short-term MD.