Eye and Brain最新文献

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.

Concussions are a mild form of traumatic brain injury (TBI) that is typically self-limited and transient with a high prevalence within our communities. Due to the vast visual network interconnectivity, visual symptoms secondary to a concussion occur about 90% of the time. A gold standard to confirm concussion acutely has not been well established. Visual function testing based on symptoms remains the standard of care in off-site evaluation for diagnosis of oculomotor dysfunction. This review covers the current diagnostic strategies for vision based disorders post-concussion for sideline testing, off-site testing, and research driven testing.

Purpose: This study investigated the relationships between structural and functional parameters in non-arteritic ischemic optic neuropathy (NAION).

Methods: This retrospective study enrolled 29 patients (58.2 ± 10.4 years old) with unilateral NAION. During the acute phase, we performed comprehensive evaluations including best-corrected visual acuity (BCVA), optical coherence tomography (OCT), optical coherence tomography angiography (OCTA), visual fields (VF), visual evoked potentials (VEP), electroretinography (ERG), and multifocal ERG (mf-ERG). At three months post-presentation, patients underwent follow-up assessments comprising visual acuity testing, perimetry, and advanced retinal imaging.

Results: During the acute phase, affected eyes demonstrated increased mean retinal nerve fiber layer (RNFL) thickness, while ganglion cell-inner plexiform layer (GCIPL) thickness decreased. Both visual fields mean deviation (MD) and VEP P100 amplitude were reduced, accompanied by prolonged peak latency. We also observed decreased P1 response density in mf-ERG. Analysis revealed significant direct correlations between GCIPL parameters and electrophysiological measurements, particularly VEP P100 amplitude and mf-ERG P1 response density. Mean GCIPL thickness, VF MD, and VEP P100 amplitude showed negative correlations with baseline logMAR VA. Baseline VF MD, VEP P100 amplitude, and minimum GCIPL thickness showed negative correlations with logMAR VA at 3-month follow-up.

Conclusion: Retinal ganglion cell layer thickness serves as a valuable indicator to objective evaluate optic nerve function in acute NAION patients. Decreases in both VEP amplitude and mf-ERG response density showed significant correlations with retinal ganglion cell layer thickness. Baseline visual field performance, VEP measurements, and minimum GCIPL thickness exhibited negative correlations visual acuity at 3-month follow-up.

Trial registration: Clinical Research Ethics Committee of Xi'an People's Hospital (NO. 20220018). Registered 27 September 2022-Retrospectively registered, https://www.medicalresearch.org.cn/. Informed consent was obtained from each participant.

Introduction: Visual Snow Syndrome (VSS) is characterized by the presence of dynamic, continuous, tiny dots in the entire visual field persisting for more than three months, with at least two associated symptoms- palinopsia, photopsia, photophobia, or nyctalopia. VSS was introduced as perpetual visual disturbance representing TV static, based on early case reports from 1995. Despite its recognition, VSS management remains vague as many cases are refractory to treatment. This literature review aims to provide a summary of all attempted treatments and efficacies to help physicians manage VSS.

Methods: The authors performed a search of articles, literature reviews, and case reports using PubMed and Google Scholar with the key words "visual snow" and "treatment". Forty-one publications were identified; however, 14 were excluded as they did not discuss treatment options or focused on medical conditions associated with visual snow, such as migraine with aura. 27 articles were found to be relevant (from 1999-2024) with treatments in patients officially diagnosed with VSS. Treatments included pharmacotherapy, tinted lenses, neuromodulation, and behavioral therapy.

Results: Based on this review of 27 publications, benzodiazepines and lamotrigine had the best effect (71.4% and 61.5% of patients had an improvement of VS symptoms on each medication, respectively). Antidepressants and AV nodal blocking agents were frequently prescribed but were less effective. VS symptoms improved with filtered lenses combined with cognitive behavioral therapy. Most treatments only partially alleviate VSS or manage associated symptoms like headache and palinopsia, rather than the visual snow itself.

Conclusion: The subjective nature of VSS has posed challenges. Among pharmacological treatments, benzodiazepines and lamotrigine have the most favorable therapeutic ratio in managing VSS. FL-41 tinted lenses consistently provide symptom relief, with cognitive behavioral therapy showing promise as an emerging intervention. Due to the small sample size, further research is recommended to enhance the applicability of findings.

Purpose: Animal studies have suggested that visual degradation impacts eye growth due to the attenuation of high spatial frequencies. However, the influence of perceptual visibility remains unclear in humans. The aim of this study was to investigate the impact of visibility on visual attenuation-related eye changes during reading.

Methods: Axial length (AxL) and choroidal thickness (ChT) changes associated with reading tasks were measured in two separate experiments. In the first experiment, the reading task was conducted under different forms of visual attenuation (contrast, resolution, defocus, noise, and crowding). For each form of visual attenuation, the text was set at a sub-threshold level of visibility, evaluated via prior measurement of reading performance, and kept constant via adaptive control of the intensity of the stimulation. Each sub-threshold reading condition was compared with a supra-threshold reading text, serving as control. In the second experiment, the effect of visibility on lens-induced defocus was further examined by comparing the effect of text stimulation with an equivalent dioptric of 5.5 D under sub- and supra-threshold levels of resolution.

Results: Near distance reading with supra-threshold texts caused eye elongation (AxL: +12.942 µm ± 2.147 µm; ChT: -3.192 µm ± 1.158 µm). Additional defocusing failed to exacerbate axial elongation under sub-threshold text visibility (mean difference: -0.135 µm ± 2.783 µm), revealing a clear inhibitory effect of lowering visibility on eye changes. Other forms of visual degradation, including crowding (mean difference: 6.153 µm ± 2.127 µm) and noise (mean difference: 5.02 µm ± 2.812 µm) also showed an inhibitory effect on eye elongation. The significant effect of crowding indicated that post-retinal mechanisms, involving attentional processes related to crowded characters, may play a role in the influence of visibility.

Conclusion: Although the featural composition of visual stimulation can drastically influence eye changes, this study revealed an important mediating role of visibility, previously underscored in chick studies, which warrants further explorations of the impact of post-retinal processes in eye growth.

Purpose: Visual System Homeobox 2 (Vsx2) is a transcription factor expressed in the developing retina that regulates tissue identity, growth, and fate determination. Several mutations in the Vsx2 gene exist in mice, including a spontaneous nonsense mutation and two targeted missense mutations originally identified in humans. Here, we expand the genetic repertoire to include a LacZ reporter allele (Vsx2^LacZ ) designed to express beta-Galactosidase (bGal) and simultaneously disrupt Vsx2 function (knock-in/knock-out).

Methods: We generated a Vsx2^LacZ reporter allele with an in-frame fusion to the Vsx2 coding sequence immediately following exon 2. Germline transmission was assessed with genomic DNA PCR and Western blot analysis was used to describe VSX2 expression from the mutant allele (LacZ). Eye size quantification and immunohistology were used to describe the embryonic and postnatal retinal phenotypes of LacZ homozygous and heterozygous mice. The contribution of Mitf to LacZ mutant microphthalmia was probed with the semi-dominant negative Mitf^mi allele.

Results: The retinal expression pattern of bGal is concordant with VSX2, and the mutant allele is recessive. Vsx2^LacZ homozygous mice have congenital bilateral microphthalmia accompanied by defects in retinal development including ectopic expression of non-retinal genes, reduced proliferation, delayed neurogenesis, aberrant tissue morphology, and an absence of bipolar interneurons - all hallmarks of Vsx2 loss-of-function. The Mitf^mi allele reduced the severity of microphthalmia caused by the Vsx2^LacZ allele. Unexpectedly, the mutant VSX2 protein is stably expressed, and there are subtle differences in eye size and early retinal neurogenesis when compared to the null mutant, ocular retardation J.

Conclusion: The perdurance of the mutant VSX2 protein combined with subtle deviations from the null phenotype leaves open the possibility that Vsx2^LacZ allele is not a complete knock-out. The Vsx2^LacZ allele exhibits loss-of-function characteristics and adds to the genetic toolkit for understanding Vsx2 function.