Retinal Diseases Research Articles

Nutraceuticals in veterinary ophthalmology: fact, fiction or both?

This review examines the use of nutraceuticals in canine and feline ocular diseases, highlighting their potential benefits and the dangers of misinformation. While certain products like curcumin, beta-glucans and resveratrol show promise against feline herpesvirus, false claims surrounding L-carnitine for cataracts are emphasised. While L-carnitine may slow cataract progression, it cannot reverse cataracts or replace surgery. Alpha-lipoic acid, an antioxidant, holds potential for diabetes-related cataracts, while lutein, zeaxanthin and other carotenoids might slow age-related changes. Despite limited evidence, neuroprotective substances like grape seed extract, omega-3 fatty acids, lutein, zeaxanthin and vitamins are used for degenerative retinal and optic nerve diseases, aiming to slow or prevent vision loss. Future research is crucial to solidify their efficacy and avoid misleading pet owners.

Characterization of the Retinal Circulation of the Mouse.

Mice are highly used in retinal research because, like humans, mice have vascularized retinas and choroidal circulation. Although the retinal circulation has been well-characterized in development, its stability during adulthood is less understood. To examine this network, we quantified several key metrics of the trilaminar vasculature. We used mice (n = 15) with transgenic fluorescent NG2-DsRed (JX: #00824), a vascular-associated label in the retina. One eye per mouse was imaged using confocal microscopy (Nikon A1 Ti2 Eclipse) and traced with ImageJ SNT tools. Using an adaptive optics scanning light ophthalmoscope, additional mice (n = 3) were imaged at single-cell resolution within the living eye to measure the same vasculature. Across mice, we found a stable retinal circulation that formed and maintained a trilaminar stratification throughout early adulthood at all eccentricities. Bridging these layers, microvessels had five distinct anatomical branching patterns. The superficial, intermediate, and deep plexuses increased in density with depth: 16.14 ± 3.61mm/mm2, 22.14 ± 6.86mm/mm2, and 31.01 ± 6.24mm/mm2, respectively. This patterning was not impacted by eccentricity or age (13-61 weeks). Similar metrics were achieved using adaptive optics scanning light ophthalmoscope in vivo with the same analysis pipeline. The mouse retinal vasculature was stable up to 50 weeks of age, providing a robust and extensive baseline dataset with which models of retinal vascular and neural disease may be compared. Vessels connecting the laminae were more complex than previously reported and represented a uniquely vulnerable population due to their relatively low density.

Platelet-Derived Growth Factor Subunit A Strengthens the Neurovascular Unit and Inhibits Retinal Vascular Regression Under Hyperoxic Conditions

Retinopathy of prematurity (ROP) is primarily caused by the exposure of preterm infants with underdeveloped blood vessels to high oxygen concentrations. This damages the astrocytes that promote normal vascular development, leading to avascularity, pathological neovascularization, and retinal detachment, and even blindness as the disease progresses. In this study, the aim was to investigate the differences in the characteristics of astrocytes and blood vessels between wild-type (WT) and genetically modified mice overexpressing platelet-derived growth factor subunit A (PDGF-A) in the retina immediately after high oxygen exposure, a protocol in the oxygen-induced retinopathy (OIR) model of ROP. Our results showed that PDGF-A mice exhibited an increased population of astrocytes and higher vascular density than WT mice and that PDGF-A strengthened the resistance to hyperoxic conditions. In the OIR model, PDGF-A mice had reduced avascular zone areas following hyperoxia exposure. Furthermore, immunostaining for NG2 and CD31 showed that pericytes tended to regress earlier than endothelial cells, particularly at the vessel edges in both WT and transgenic mice, indicating relatively higher susceptibility to hyperoxia-induced damage. These findings suggest that PDGF-A plays a crucial role in stabilizing retinal vessels and may serve as a novel therapeutic target for ROP, highlighting the potential significance of PDGF-A in the pathological mechanisms of retinal diseases.

Integration and Differentiation of Transplanted Human iPSC-Derived Retinal Ganglion Cell Precursors in Murine Retinas

Optic neuropathy such as glaucoma, stemming from retinal ganglion cell (RGC) degeneration, is a leading cause of visual impairment. Given the substantial loss of RGCs preceding clinical detection of visual impairment, cell replacement therapy emerges as a compelling treatment strategy. Human-induced pluripotent stem cells (hiPSCs) serve as invaluable tools for exploring the developmental processes and pathological mechanisms associated with human RGCs. Utilizing a 3D stepwise differentiation protocol for retinal organoids, we successfully differentiated RGC precursors from hiPSCs harboring a BRN3B-GFP RGC reporter, verified by GFP expression. Intravitreal transplantation of enriched RGC precursors into healthy or N-methyl-D-aspartate (NMDA)-injured mice demonstrated their survival, migration, and integration into the proper retinal layer, the ganglion cell layer, after 3 weeks. Notably, these transplanted cells differentiated into marker-positive RGCs and extended neurites. Moreover, enhanced cell survival was observed with immunosuppressive and anti-inflammatory treatments of the host prior to transplantation. These data underscore the potential of transplanted RGC precursors as a promising therapeutic avenue for treating degenerative retinal diseases resulting from RGC dysfunction.

Molecular characterization and sub-retinal transplantation of hypoimmunogenic human retinal sheets in a minipig model of severe photoreceptor degeneration.

Retinal degenerative diseases affect millions of people worldwide, and legal blindness is generally associated with the loss of cone photoreceptors located in the central region of the retina called the macula. Currently, there is no treatment to replace the macula. Addressing this unmet need, we employed control isogenic and hypoimmunogenic induced pluripotent stem cell lines to generate spontaneously polarized retinal sheets (RSs). RSs were enriched in retinal progenitor and cone precursor cells, which could differentiate into mature S- and M/L-cones in long-term cultures. Single-cell RNA-seq analysis showed that RSs recapitulate the ontogeny of the developing human retina. Isolation of neural rosettes for sub-retinal transplantation effectively eliminated unwanted cells such as RPE cells. In a porcine model of chemically induced retinal degeneration, grafts integrated the host retina and formed a new, yet immature, photoreceptor layer. In one transplanted animal, functional and immunohistochemical assays suggest that grafts exhibited responsiveness to light stimuli and established putative synaptic connections with host bipolar neurons. This study underscores the potential and challenges of RSs for clinical applications.

Using deep learning to diagnose retinal diseases through medical image analysis

Using deep learning to diagnose retinal diseases through medical image analysis

Three-Dimensional Bioprinting for Retinal Tissue Engineering

Three-dimensional bioprinting (3DP) is transforming the field of regenerative medicine by enabling the precise fabrication of complex tissues, including the retina, a highly specialized and anatomically complex tissue. This review provides an overview of 3DP’s principles, its multi-step process, and various bioprinting techniques, such as extrusion-, droplet-, and laser-based methods. Within the scope of biomimicry and biomimetics, emphasis is placed on how 3DP potentially enables the recreation of the retina’s natural cellular environment, structural complexity, and biomechanical properties. Focusing on retinal tissue engineering, we discuss the unique challenges posed by the retina’s layered structure, vascularization needs, and the complex interplay between its numerous cell types. Emphasis is placed on recent advancements in bioink formulations, designed to emulate retinal characteristics and improve cell viability, printability, and mechanical stability. In-depth analyses of bioinks, scaffold materials, and emerging technologies, such as microfluidics and organ-on-a-chip, highlight the potential of bioprinted models to replicate retinal disease states, facilitating drug development and testing. While challenges remain in achieving clinical translation—particularly in immune compatibility and long-term integration—continued innovations in bioinks and scaffolding are paving the way toward functional retinal constructs. We conclude with insights into future research directions, aiming to refine 3DP for personalized therapies and transformative applications in vision restoration.

Oxygen-dependent alternative mRNA splicing and a cone-specific motor protein revealed by single-cell RNA sequencing in hypoxic retinas

Restricted oxygen supply in the aging eye may lead to hypoxic conditions in the outer retina and contribute not only to physiological aging but also to nonhereditary degenerative retinal diseases. To understand the hypoxic response of specific retinal cell types, we performed single-cell RNA sequencing of retinas isolated from mice exposed to hypoxia. Significantly upregulated expression of marker genes in hypoxic clusters confirmed a general transcriptional response to hypoxia. By focusing on the hypoxic response in photoreceptors, we identified and confirmed a kinesin motor protein (Kif4) that was specifically and strongly induced in hypoxic cones. In contrast, RNA-binding proteins Rbm3 and Cirbp were differentially expressed across clusters but demonstrated isoform switching in hypoxia. The resulting short variants of these gene transcripts are connected to epitranscriptomic regulation, a notion supported by the differential expression of writers, readers and erasers of m6A RNA methylations in the hypoxic retina. Our data indicate that retinal cells adapt to hypoxic conditions by adjusting their transcriptome at various levels including gene expression, alternative splicing and the epitranscriptome. Adaptational processes may be cell-type specific as exemplified by the cone-specific upregulation of Kif4 or general like alternative splicing of RNA binding proteins.

Reactive retinal vasodilation may mask capillary loss in eyes without diabetic retinopathy and isolated neurodegeneration

Reactive retinal vasodilation occurs in healthy individuals when the demand for oxygen surpasses the supply that the vascular bed can provide. This phenomenon may also occur in individuals with diabetes who do not have diabetic retinopathy, potentially masking circulation deficiencies caused by early capillary closure. As a result, eyes with reactive retinal vasodilation may show a seemingly normal circulation area, while also displaying other diabetes-related changes such as neurodegeneration. Our hypothesis suggests that in eyes without overt ischemia, which is one of the phenotypes of diabetic retinal disease, neurodegeneration could be the result of undetected ischemia in the presence of reactive retinal vasodilation. We propose methodologies to investigate this hypothesis, including the assessment of retinal capillaries using optical coherence tomography angiography, as well as the measurement of neurodegeneration markers such as retinal sensitivity, electroretinogram amplitude reductions, and retinal layer thinning. Additionally, we outline an approach for estimating the contribution of large retinal vessels to the percentage of circulation within a measured retinal area, using variables such as vessel length density and vessel area density. If our hypothesis is confirmed, it could lead to the early identification of ischemia before the onset of diabetic retinopathy and offer an opportunity to assess interventions when endothelial and neural damage can still be mitigated.

Prevalence and diversity of retinal disease in adults with Down syndrome.

While epidemiologic data exists for some ophthalmic diseases in people with Down Syndrome (DS), like strabismus and amblyopia, no studies explore the prevalence of retinal disease in people with DS on a large scale. This study utilized a literature review and exploratory epidemiology analysis to examine patterns of retinal disease in people with DS. To evaluate previous studies on physiology and/or anatomy in retinal models representing DS or in the retinas of people with DS, all relevant terms related to Down Syndrome, retina, and retinal diseases were searched in PubMed and Scopus. Data from the health platform TriNetX was then utilized to determine the prevalence and prevalence odds ratio (POR) of retinal disorders, including diabetic retinopathy and age-related macular degeneration (AMD), within the U.S. adult population with DS. The final literature review included 28 of 535 screened studies and found that a DS diagnosis was associated with atypical retinal vascularization, retinal thickening, and abnormal neuronal development. Of 55,198,979 individuals included in the population study, 97,795 (0.18%) had a recorded DS diagnosis. Compared to the population without DS, the population with DS had significantly increased PORs for any retinal diagnosis (3.78, 95% CI 3.63-3.93), for 16 of 18 recorded individual retinal diagnoses, and for 4 of 5 major diagnostic categories, including diabetic retinopathy (2.56, 95% CI 2.33-2.82) and macular degeneration (4.01, 95% CI 3.42-4.71). The conclusion is that retinal anomalies common to people with DS likely contribute to higher rates of recorded retinal disease. However, future studies should evaluate this relationship.

Conditional Immortalization Using SV40 Large T Antigen and Its Effects on Induced Pluripotent Stem Cell Differentiation Toward Retinal Progenitor Cells.

Current treatments for retinal degenerative diseases are limited and cell replacement therapies, in tandem with a supportive biomaterial scaffold, serve as a promising emerging option. However, the development and in vitro testing of these therapies require large quantities of human retinal progenitor cells (RPCs) to thoroughly assess the impact of material properties, culture conditions, and surgical parameters on cell survival and fate to refine and optimize this approach. Although induced pluripotent stem cells (iPSCs) are an ideal cell source for human RPC derivation, large-scale production is resource-intensive and requires specialized expertise. In this study, our objective was to address this barrier by creating conditional, Tet-On SV40-T immortalized RPCs derived from human iPSCs. In our approach, we employ the Tet-On system to conditionally immortalize RPCs by inducing a SV40 large T (SV40-T) antigen, a gene known to influence cell cycle regulation and differentiation. We transduced human iPSCs with the Tet-On SV40-T system and analyzed their proliferation and RPC differentiation capabilities in the presence and absence of doxycycline (a tetracycline class of antibiotics). Our results revealed that while SV40-T immortalization increased cell proliferation, it adversely impacted the expression of crucial RPC markers (PAX6, SOX2, CHX10), leading to a significant loss of RPC identity and multipotency. This de-differentiation was irreversible, even after removing doxycycline, indicating permanent alterations in differentiation potential. Overall, this study highlights the challenges associated with generating and maintaining an immortal human RPC cell line, particularly with respect to balancing proliferation and differentiation. Our findings prompt further research into optimizing conditional immortalization techniques, culture conditions, and proliferation timing to maintain the integrity and functional characteristics of RPCs. Such advancements are crucial for reducing labor and costs associated with in vitro testing of therapeutics as we work toward the development of improved stem cell-based interventions for retinal disease.

Abca4, mutated in Stargardt Disease, is required for cone outer segment structural integrity.

Stargardt Disease (STGD), the leading cause of inherited childhood blindness, is primarily caused by mutations in the ABCA4 gene, yet the underlying mechanisms of photoreceptor degeneration remain elusive, partly due to limitations in existing animal disease models. To expand our understanding, we mutated the ABCA4 paralogues, abca4a and abca4b, in zebrafish, which has a cone-rich retina. Our study unveiled striking dysmorphology and elongation of cone outer segments in abca4a;abca4b double mutants, alongside reduced phagocytosis by the retinal pigmented epithelium. We report that Abca4 protein forms a distinctive stripe along the length of cone outer segments, suggesting a potential structural role. We further show that wild-type cone outer segments constitutively present externalized phosphatidylserine, an 'eat-me' signal, and this pattern is disrupted in abca4a;abca4b double mutants, potentially contributing to reduced RPE phagocytic activity. More broadly, constitutive presentation of the "eat-me" signal by cone outer segments, if conserved in humans, has important implications for other retinal degenerative diseases, including age-related macular degeneration. This zebrafish model provides novel insights into cone dysfunction and presents a promising platform for unraveling the mechanisms of STGD pathogenesis and advancing therapeutic interventions.

Optideneffnet: Deep Learning Framework For Retinal Diseases Prediction

The eye is the primary sensory organ involved in vision. Since some eye conditions might result in blindness, it is important to diagnose and treat them as soon as possible. In ophthalmic diagnostics, it is essential to identify various ocular illnesses from fundus images. On the other hand, subjectivity and mistake arise when ophthalmologists manually detect images. As a result, several automation techniques are developed, however they need to improve in terms of classification accuracy. This work proposes a novel multi-label automated Deep Learning (DL) prediction system called OptiDenEffNet, which can identify various retinal illnesses, as a solution for such challenges. The study begins with an extensive pre-processing step includes label encoding, data cleaning and normalization. The proposed OptiDenEffNet model, which combines many DL blocks, and the Attention Block, which act as feature descriptors, are then used to extract discriminative deep feature representations. Finally, a Discriminative Gated Recurrent Unit (DGRU), a highly developed prediction model is used. This DGRU can provide a probability distribution that precisely predict eye disorders on particular age by incorporating a Softmax layer to its architecture. Extensive tests are conducted on the challenging Ocular Disease Recognition Dataset using Python platform. The proposed model achieves the maximum accuracy of 98.269% and 99.691% in the 70:30 and 80:20 data splits respectively. The results specify that the proposed OptiDenEffNet model works better than state-of-the-art for predict retinal diseases.

Integrative analysis and knowledgebase construction of key candidate genes and pathways in age-related macular degeneration

Age-related macular degeneration is a retinal disease that severely impacts vision in the older population. Its gene-related heterogeneity has not been fully studied, increasing the burden of precise treatment, prevention and prognosis. Genetic variation and related information were collected, annotated and expanded from multiple related websites, and all the data were integrated into the online platform AMDGKB. Users can visit this database via the following link: http://amdgd.bioinf.org.cn/for their personalized applications knowledge-guided modeling and applications. This study also explored the heterogeneity of ethnicity and AMD subtypes via genetic variation, functional enrichment analysis and protein‒protein interactions.These results suggest that VEGFA, MT2A, CCL2 and SERPINF1 play different roles in the development of AMD in different ethnic groups. The enrichment analysis also revealed differences in the pathogenesis pathways of different ethnic groups and AMD subtypes. This study highlights that genetic heterogeneity needs to be considered in the process of diagnosis and treatment. AMDGKB provides information for investigating the transformation of genetic variation during AMD progression, as well as for future personalized applications in the diagnosis and prognosis of AMD.

Spontaneously Immortalised Nonhuman Primate Müller Glia Cell Lines as Source to Explore Retinal Reprogramming Mechanisms for Cell Therapies.

Cell replacement therapies for ocular diseases characterised by photoreceptors degeneration are challenging due to poor primary cell survival in culture. A stable retinal cell source to replace lost photoreceptors holds promise. Müller glia cells play a pivotal role in retinal homoeostasis by providing metabolic and structural support to retinal neurons, preventing aberrant photoreceptors migration, and facilitating safe glutamate uptake. In fish and amphibians, injured retinas regenerate due to Müller-like glial stem cells, a phenomenon absent in the mammalian retina for unknown reasons. Research on Müller cells has been complex due to difficulties in obtaining pure cell population and their rapid de-differentiation in culture. While various Müller glia cell lines from human and rats are described, no nonhuman primate Müller glia cell line is currently available. Here, we report spontaneously immortalised Müller glia cell lines derived from macaque neural retinas that respond to growth factors and expand indefinitely in culture. They exhibit Müller cells morphology, such as an elongated shape and cytoplasmic projections, express Müller glia markers (VIMENTIN, GLUTAMINE SYNTHASE, glutamate-aspartate transporter, and CD44), and express stem cell markers such as PAX6 and SOX2. In the presence of factors that induce photoreceptor differentiation, these cells show a shift in gene expression patterns suggesting a state of de-differentiation, a phenomenon known in reprogrammed mammalian Müller cells. The concept of self-renewing retina might seem unfeasible, but not unprecedented. While vertebrate Müller glia have a regeneration potential absent in mammals, understanding the mechanisms behind reprogramming of Müller glia in mammals could unlock their potential for treating retinal degenerative diseases.

Health Benefits of Epigallocatechin Gallate and Forskolin with a Special Emphasis on Glaucoma and Other Retinal Diseases

This review highlights the therapeutic potential of epigallocatechin gallate (EGCG) and forskolin in managing retinal diseases, with a focus on glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy. EGCG, a potent polyphenol from green tea, exhibits significant antioxidant, anti-inflammatory, and neuroprotective effects, making it a promising candidate for reducing oxidative stress and inflammation in ocular tissues. Forskolin, a diterpene from Coleus forskohlii, increases cyclic AMP (cAMP) levels, which helps lower intraocular pressure (IOP) and provides neuroprotection. Both compounds target critical pathways involved in retinal disease progression, including oxidative stress, mitochondrial dysfunction, and inflammation, offering complementary therapeutic benefits. This review consolidates preclinical and clinical studies, highlighting the potential of EGCG and forskolin as adjunctive or alternative treatments for retinal diseases. Future research should explore the synergistic effects of these compounds, particularly in combination therapies aimed at addressing multiple pathogenic mechanisms in retinal health.

Retinal pigment epithelial cells reduce vascular leak and proliferation in retinal neovessels

In multiple neurodegenerative diseases, including age-related macular degeneration, retinitis pigmentosa, and macular telangiectasia type 2 (MacTel), retinal pigment epithelial (RPE)-cells proliferate and migrate into the neuroretina, forming intraretinal pigment plaques. Though these pigmentary changes are hallmarks of disease progression, it is unknown if their presence is protective or detrimental.Here, we first evaluated the impact of pigment plaques on vascular changes and disease progression in MacTel. In a retrospective, longitudinal study, we analyzed multimodal retinal images of patients with MacTel and showed that pigment plaques were associated with decreased vascular leakage and stabilized neovascular growth. We then modeled the underlying pathomechanisms of pigment plaque formation in aberrant neovascular growth using the very-low-density lipoprotein receptor mutant (Vldlr−/−) mouse. Our data indicated that during RPE-proliferation, migration and accumulation along neovessels RPE-cells underwent epithelial-mesenchymal transition (EMT). Pharmacologic inhibition of EMT in Vldlr−/− mice decreased pigment coverage, and exacerbated neovascular growth and vascular leakage.Our findings indicate that the proliferation, migration and perivascular accumulation of RPE-cells stabilize vascular proliferation and exudation, thereby exerting a protective effect on the diseased retina. We conclude that interfering with this “natural repair mechanism” may have detrimental effects on the course of the disease and should thus be avoided.

The subsequent risk of retinal vein occlusion disease after sinusitis diagnosis: a nationwide population-based study

Retinal vein occlusion (RVO) is a common retinal vascular disease that causes visual impairment. However, there is limited evidence regarding the relationship between sinusitis and risk of RVO. This study investigated the association between sinusitis and the subsequent risk of RVO disease. A retrospective cohort study was conducted and patients with sinusitis or RVO were selected from the National Health Insurance Research Database (NHIRD) of Taiwan. In this population-based study, we identified a total of 131,532 sinusitis patients, who were matched with 263,064 non-sinusitis individuals based on sex and age. The Cox proportional hazard regression was applied to demonstrate the adjusted hazard ratio (aHR) with 95% confidence interval (CI) of main outcomes. Our results showed that the crude hazard ratio (cHR) for the risk of RVO was 1.35 (95% CI: 1.20–1.52) in the sinusitis cohort compared with the non-sinusitis cohort. After adjustment for demographics and comorbidities in the multivariable cox regression, the adjusted hazard ratio (aHR) was 1.28 (95% CI: 1.13–1.44). Moreover, statistically significant differences were observed in the 14-year cumulative incidence of RVO (p < 0.0001), central RVO (p = 0.0002), and branch RVO (p = 0.0004) between the sinusitis and non-sinusitis cohorts. In conclusion, our study revealed that patients with sinusitis were at higher risk of being diagnosed with RVO.

A Comprehensive Study of Supervised Learning Models on the OCTID Dataset for Retinal Disease Detection with Future Directions

This paper presents a critical analysis of recent approaches to supervised learning techniques on the OCTID database that are important in the early diagnosis of retinal diseases such as AMD, CSR, DME, and MH. The review concentrates on methodologies, experimental configurations, and assessments of various machine learning and deep learning techniques. The limitations observed in the current work are in terms of computational complexity, possible limitation in labeling, and lack of extensive experimentation using videos with OCT. For future work, we suggest using semi-supervised learning as they are more accurate and less costly in medical applications.

Detection of Disease Features on Retinal OCT Scans Using RETFound

Eye diseases such as age-related macular degeneration (AMD) are major causes of irreversible vision loss. Early and accurate detection of these diseases is essential for effective management. Optical coherence tomography (OCT) imaging provides clinicians with in vivo, cross-sectional views of the retina, enabling the identification of key pathological features. However, manual interpretation of OCT scans is labor-intensive and prone to variability, often leading to diagnostic inconsistencies. To address this, we leveraged the RETFound model, a foundation model pretrained on 1.6 million unlabeled retinal OCT images, to automate the classification of key disease signatures on OCT. We finetuned RETFound and compared its performance with the widely used ResNet-50 model, using single-task and multitask modes. The dataset included 1770 labeled B-scans with various disease features, including subretinal fluid (SRF), intraretinal fluid (IRF), drusen, and pigment epithelial detachment (PED). The performance was evaluated using accuracy and AUC-ROC values, which ranged across models from 0.75 to 0.77 and 0.75 to 0.80, respectively. RETFound models display comparable specificity and sensitivity to ResNet-50 models overall, making it also a promising tool for retinal disease diagnosis. These findings suggest that RETFound may offer improved diagnostic accuracy and interpretability for specific tasks, potentially aiding clinicians in more efficient and reliable OCT image analysis.