Search Results (86)

The retina is highly sensitive to oxygen and blood supply, and hypoxia plays a key role in retinal diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). Müller glial cells, which are essential for retinal homeostasis, respond to injury and hypoxia with reactive gliosis, characterized by the upregulation of the glial fibrillary acidic protein (GFAP) and vimentin, cellular hypertrophy, and extracellular matrix changes, which can impair retinal function and repair. The retinal pigment epithelium (RPE) supports photoreceptors, forms part of the blood–retinal barrier, and protects against oxidative stress; its dysfunction contributes to retinal degenerative diseases such as AMD, retinitis pigmentosa (RP), and Stargardt disease (SD). Extracellular vesicles (EVs) play a crucial role in intercellular communication, protein homeostasis, and immune modulation, and have emerged as promising diagnostic and therapeutic tools. Understanding the role of extracellular vesicles’ (EVs’) signaling machinery of glial cells and the retinal pigment epithelium (RPE) is critical for developing effective treatments for retinal degeneration. In this study, we investigated the bidirectional EV-mediated crosstalk between RPE and Müller cells under hypoxic conditions and its impact on cellular metabolism and retinal cell integrity. Our findings demonstrate that RPE-derived extracellular vesicles (RPE EVs) induce time-dependent metabolic reprogramming in Müller cells. Short-term exposure (24 h) promotes pathways supporting neurotransmitter cycling, calcium and mineral absorption, and glutamate metabolism, while prolonged exposure (72 h) shifts Müller cell metabolism toward enhanced mitochondrial function and ATP production. Conversely, Müller cell-derived EVs under hypoxia influenced RPE metabolic pathways, enhancing fatty acid metabolism, intracellular vesicular trafficking, and the biosynthesis of mitochondrial co-factors such as ubiquinone. Proteomic analysis revealed significant modulation of key regulatory proteins. In Müller cells, hypoxic RPE-EV exposure led to reduced expression of Dyskerin Pseudouridine Synthase 1 (DKc1), Eukaryotic Translation Termination Factor 1 (ETF1), and Protein Ser/Thr phosphatases (PPP2R1B), suggesting alterations in RNA processing, translational fidelity, and signaling. RPE cells exposed to hypoxic Müller cell EVs exhibited elevated Ribosome-binding protein 1 (RRBP1), RAC1/2, and Guanine Nucleotide-Binding Protein G(i) Subunit Alpha-1 (GNAI1), supporting enhanced endoplasmic reticulum (ER) function and cytoskeletal remodeling. Functional assays also revealed the compromised barrier integrity of the outer blood–retinal barrier (oBRB) under hypoxic co-culture conditions. These results underscore the adaptive but time-sensitive nature of retinal cell communication via EVs in response to hypoxia. Targeting this crosstalk may offer novel therapeutic strategies to preserve retinal structure and function in ischemic retinopathies. Full article

Stargardt’s disease (STGD1) is an autosomal recessive juvenile macular degeneration caused by mutations in the ABCA4 gene, impairing clearance of toxic retinoid byproducts in the retinal pigment epithelium (RPE). This leads to lipofuscin accumulation, oxidative stress, photoreceptor degeneration, and central vision loss. Over 1200 pathogenic/likely pathogenic ABCA4 variants highlight the genetic heterogeneity of STGD1, which manifests as progressive central vision loss, with phenotype influenced by deep intronic variants, modifier genes, and environmental factors like light exposure. ABCA4 variants also show variable penetrance and geographical prevalence. With no approved treatment, investigational therapies target different aspects of disease pathology. Small-molecule therapies target vitamin A dimerization (e.g., ALK-001), inhibit lipofuscin accumulation (e.g., soraprazan), or modulate the visual cycle (e.g., emixustat hydrochloride). Gene therapy trials explore ABCA4 supplementation including strategies like RNA exon editing (ACDN-01) and bioengineered ambient light-activated OPSIN. RORA gene therapy (Phase 2/3) addresses oxidative stress, inflammation, lipid metabolism, and complement system dysregulation. Trials like DRAGON (Phase 3, tinlarebant), STARLIGHT (phase 2, bioengineered OPSIN) show promise, but optimizing efficacy remains challenging. With the key problem of establishing genotype–phenotype correlations, the future of STGD1 therapy may rely on approaches targeting oxidative stress, lipid metabolism, inflammation, complement regulation, and genetic repair. Full article

Gene therapy has emerged as a promising treatment for several eye diseases since it may restore vision and stop blindness. Many eye diseases, including retinitis pigmentosa and macular degeneration, have historically been rather difficult to treat and usually cause permanent vision loss. However, thanks to advances in gene therapy, many disorders can now be effectively targeted and genetically changed, providing a safer, more direct, maybe even curative approach. By introducing, altering, or repairing specific genes inside the eye, gene therapy seeks to fix the defective genes causing these disorders, thereby improving general eye health and visual ability. Voretigene neparvovec is one FDA- and EMA-approved treatment for RPE65 mutations. Retinitis pigmentosa, age-related macular degeneration, X-linked retinoschisis, choroideremia, and Stargardt disease are among the several eye disorders still under clinical trials, and experimental treatment is in progress. As research on gene therapy develops, it opens the path for groundbreaking treatments that could fundamentally change the ophthalmic care scene. Full article

Fundus autofluorescence (FAF) is a non-invasive retinal imaging technique that helps visualize naturally occurring fluorophores, such as lipofuscin, and provides valuable insight into retinal diseases—particularly inherited retinal diseases (IRDs). FAF is especially useful in detecting subclinical or early-stage IRDs and in monitoring disease progression over time. In Stargardt disease, areas of decreased autofluorescence correlate with disease progression and have been proposed as a biomarker for future clinical trials. FAF can also help differentiate Stargardt disease from other macular dystrophies. In retinitis pigmentosa, hyperautofluorescent rings are a common feature on FAF and serve as an important marker for disease monitoring, especially as changes align with those seen on other imaging modalities. FAF is valuable in tracking progression of choroideremia and may help identify disease carrier status. FAF has also improved the characterization of mitochondrial retinopathies such as maternally inherited diabetes and deafness. As a rapid and widely accessible imaging modality, FAF plays a critical role in both diagnosis and longitudinal care of patients with IRDs. Full article

Pupil cycle time (PCT) estimates the dynamics of a biofeedback loop established between pupil size and stimulus luminance, size or colour. The PCT is useful for probing the functional integrity of the retinopupillary circuits, and is therefore potentially applicable for assessing the effects of damage due to retinopathies or neuropathies. In previous studies, PCT was measured by manually counting the number of pupil oscillations during a fixed period to calculate the PCT. This method is scarce, requires a good expertise and cannot be used to estimate several PCT parameters, such as the oscillation amplitude or variability. We have developed a computerised setup based on eye-tracking that expands the possibilities of characterising PCT along several dimensions: oscillation frequency and regularity, amplitude and variability, which can be used with a large palette of stimuli (different colours, sizes, shapes or locations), and further allows measuring blinking frequency and eye movements. We used this method to characterise the PCT in young control participants as well as in patients with several pathologies, including age-related macular degeneration (AMD), diabetic retinopathy (DR), retinitis pigmentosa (RP), Stargardt disease (SD), and Leber hereditary optic neuropathy (LHON). We found that PCT is very regular and stable in young healthy participants, with little inter-individual variability. In contrast, several PCT features are altered in older healthy participants as well as in ocular diseases, including slower dynamics, irregular oscillations, and reduced oscillation amplitude. The distinction between patients and healthy participants based on the calculation of the area under the curve of the receiver operating characteristics (AUC of ROC) were dependent on the pathologies and stimuli (0.7 < AUC < 1). PCT nevertheless provides relevant complementary information to assess the physiopathology of ocular diseases and to probe the functioning of retino-pupillary circuits. Full article

Dark adaptometry is a non-invasive functional test that assesses the retina’s ability to recover sensitivity in low-light conditions following photobleaching. This review explores the physiological mechanisms underlying dark adaptation (DA), including photopigment regeneration and the critical role of the retinal pigment epithelium in the visual cycle. We detail clinical protocols for dark adaptometry using modern instruments such as the AdaptDx, highlighting methodological advances that improve testing efficiency and reproducibility. The clinical utility of dark adaptometry is examined across a range of inherited and acquired retinal disorders, including age-related macular degeneration (AMD), retinitis pigmentosa (RP), Stargardt disease, diabetic retinopathy (DR), cone–rod dystrophy (CRD), vitamin A deficiency, and congenital stationary night blindness (CSNB). Dark adaptometry has emerged as a sensitive biomarker capable of detecting functional deficits before structural changes are evident, making it a valuable tool for early diagnosis and monitoring disease progression. However, limitations such as age-related variability, patient compliance, and lack of standardization remain challenges to broader clinical adoption. Continued refinement of dark adaptometry protocols and instrumentation is essential to maximize its diagnostic potential in ophthalmic practice. Full article

Retinal degeneration, characterized by the progressive loss of photoreceptors, retinal pigment epithelium cells, and/or ganglion cells, is a leading cause of vision impairment. These diseases are generally classified as inherited (e.g., retinitis pigmentosa, Stargardt disease) or acquired (e.g., age-related macular degeneration, diabetic retinopathy, glaucoma) ocular disorders that can lead to blindness. Available treatment options focus on managing symptoms or slowing disease progression and do not address the underlying causes of these diseases. However, recent advancements in regenerative medicine offer alternative solutions for repairing or protecting degenerated retinal tissue. Stem and progenitor cell therapies have shown great potential to differentiate into various retinal cell types and can be combined with gene editing, extracellular vesicles and exosomes, and bioactive molecules to modulate degenerative cellular pathways. Additionally, gene therapy and neuroprotective molecules play a crucial role in enhancing the efficacy of regenerative approaches. These innovative strategies hold the potential to halt the progression of retinal degenerative disorders, repair or replace damaged cells, and improve visual function, ultimately leading to a better quality of life for those affected. Full article

Stem cell therapy has emerged as a promising approach for treating various retinal diseases, particularly degenerative retinal diseases such as geographic atrophy in age-related macular degeneration (AMD), retinitis pigmentosa (RP), and Stargardt disease. A wide variety of imaging techniques have been employed in both preclinical and clinical settings to assess the efficacy and safety of stem cell therapy for retinal diseases. These techniques can be classified into two categories: methods for imaging stem cells and those for the overall morphology and function of the retina. The techniques employed for stem cell imaging include optical imaging, magnetic resonance imaging (MRI), and radionuclide imaging. Additional imaging techniques include fundus photography, fluorescein angiography, and fundus autofluorescence. Each technique has its own advantages and disadvantages, and thus, the use of multimodal imaging can help to overcome the shortcomings and achieve a more comprehensive evaluation of stem cell therapy in retinal disease. This review discusses the characteristics of the main techniques and cell-labeling techniques applied in stem cell therapy, with a particular focus on the applications of multimodal imaging. Furthermore, this review discusses the challenges and prospects of multimodal imaging in stem cell therapy for retinal disease. Full article

Stargardt disease (STGD1), the most common retinal dystrophy caused by pathogenic variants of the biallelic ABCA4 gene, results in irreversible vision loss. This cross-sectional case series study analyzes 18 unrelated Stargardt disease (STGD1) patients from southeast China, examining clinical and genetic features. Ophthalmological assessments included BCVA, ophthalmoscopy, fundus photography, and autofluorescence, with ultra-widefield OCT angiography carried out on one patient. Genetic testing uses targeted exome sequencing for eye disease genes. The mean age of onset was 44.3 years for adult onset (6 patients) and 9.6 years for childhood/adolescent onset (12 patients). The mean logMAR visual acuity was 0.96 (right eye) and 0.91 (left eye). Eight novel ABCA4 variants were found, including two nonsense, two frameshift deletions, one copy number variant, one splice-site alternation, and two deep intronic variants. The genotypes are as follows: 77.8% (14/18) biallelic heterozygous, 16.7% (3/18) homozygous, and one patient with three variants. The study underscores STGD1’s phenotypic and genotypic diversity, expands the ABCA4 mutation spectrum, and offers insights into therapeutic strategies. Full article

Pediatric macular disorders are a diverse group of inherited retinal diseases characterized by central vision loss due to dysfunction and degeneration of the macula, the region of the retina responsible for high-acuity vision. Common disorders in this category include Stargardt disease, Best vitelliform macular dystrophy, and X-linked retinoschisis. These conditions often manifest during childhood or adolescence, with symptoms such as progressive central vision loss, photophobia, and difficulty with fine visual tasks. Underlying mechanisms involve genetic mutations that disrupt photoreceptor and retinal pigment epithelium function, accumulating toxic byproducts, impaired ion channel activity, or structural degeneration. Advances in imaging modalities like optical coherence tomography and fundus autofluorescence have improved diagnostic accuracy and disease monitoring. Emerging therapies are transforming the treatment landscape. Gene therapy and genome editing hold promise for addressing the genetic basis of these disorders, while stem cell-based approaches and pharmacological interventions aim to restore retinal function and mitigate damage. Personalized medicine, driven by genomic sequencing, offers the potential for tailored interventions. Despite current challenges, ongoing research into molecular mechanisms, advanced imaging, and innovative therapies provides hope for improving outcomes and quality of life in children with macular disorders. Full article

All-trans-retinal (atRAL)-induced photoreceptor atrophy and retinal degeneration are hallmark features of dry age-related macular degeneration (AMD) and Stargardt disease type 1 (STGD1). The toxicity of atRAL is closely related to the generation of reactive oxygen species (ROS). Quercetin, a natural product, is known for its potent antioxidant properties; however, its effects in mitigating atRAL-mediated retinal damage remains unclear. This study investigated the protective effects of quercetin against atRAL-induced photoreceptor damage. Using atRAL-loaded 661W photoreceptor cells, we evaluated cell viability, ROS generation, and endoplasmic reticulum (ER) stress under quercetin treatment. Quercetin significantly restored the cell viability (to 70%) and reduced ROS generation in atRAL-treated 661W cells. Additionally, Western blot analysis demonstrated that quercetin mitigated protein kinase RNA-like ER kinase (PERK) signaling, preventing ER stress-induced apoptosis. Importantly, in Abca4^−/−Rdh8^−/− mice, an animal model of light-induced atRAL accumulation in the retina, quercetin treatment effectively alleviated light-exposed photoreceptor atrophy and retinal degeneration by attenuating PERK signaling. Thus, quercetin protected photoreceptor cells from atRAL-induced damage by inhibiting ROS generation and PERK signaling, which suggests its potential as a therapeutic agent for atRAL-related retinal degeneration. Full article

Background/Objectives: Stargardt disease (STGD1) is an autosomal recessive disorder caused by pathogenic variants in ABCA4 that affects the retina and is characterised by progressive central vision loss. The onset of disease manifestations varies from childhood to early adulthood. Methods: Whole exome (WES), whole gene, and whole genome sequencing (WGS) were performed for a patient with STGD1. Results: WES revealed a heterozygous pathogenic missense variant in ABCA4, but no second pathogenic variant was found. ABCA4 whole-gene sequencing, subsequent WGS, and segregation analysis identified a complex deep-intronic allele (NM_000350.2(ABCA4):c.[1555-5882C>A;1555-5784C>G]) in trans to the missense variant. Minigene assays combined with nanopore sequencing were performed to characterise this deep-intronic complex allele in more detail. Surprisingly, the reference minigene revealed the existence of two pseudoexons in intron 11 of the ABCA4 gene that are included in low-abundance (<1%) transcripts. Both pseudoexons could be confirmed in cDNA derived from wildtype retinal organoids. Despite mild splicing predictions, the variant minigene revealed that the complex deep-intronic allele substantially increased the abundance of transcripts that included the pseudoexon overlapping with the variants. Two antisense oligonucleotides (AONs) were designed to rescue the aberrant splicing events. Both AONs increased the proportion of correctly spliced transcripts, and one of them rescued correct splicing to reference levels. Conclusions: Minigene assays combined with nanopore sequencing proved instrumental in identifying low-abundance transcripts including pseudoexons from wildtype ABCA4 intron 11, one of which was substantially increased by the complex allele. Full article

Stargardt disease, one of the most common forms of inherited retinal diseases, affects individuals worldwide. The primary cause is mutations in the ABCA4 gene, leading to the accumulation of toxic byproducts in the retinal pigment epithelium (RPE) and subsequent photoreceptor cell degeneration. Over the past few years, research on Stargardt disease has advanced significantly, focusing on clinical and molecular genetics. Recent studies have explored various innovative therapeutic approaches, including gene therapy, stem cell therapy, and pharmacological interventions. Gene therapy has shown promise, particularly with adeno-associated viral (AAV) vectors capable of delivering the ABCA4 gene to retinal cells. However, challenges remain due to the gene’s large size. Stem cell therapy aims to replace degenerated RPE and photoreceptor cells, with several clinical trials demonstrating safety and preliminary efficacy. Pharmacological approaches focus on reducing toxic byproduct accumulation and modulating the visual cycle. Precision medicine, targeting specific genetic mutations and pathways, is becoming increasingly important. Novel techniques such as clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 offer potential for directly correcting genetic defects. This review aims to synthesize recent advancements in understanding and treating Stargardt disease. By highlighting breakthroughs in genetic therapies, stem cell treatments, and novel pharmacological strategies, it provides a comprehensive overview of emerging therapeutic options. Full article

Stargardt disease (STGD1), associated with biallelic variants in the ABCA4 gene, is the most common heritable macular dystrophy and is currently untreatable. To identify potential treatment targets, we characterized surviving STGD1 photoreceptors. We used clinical data to identify macular regions with surviving STGD1 photoreceptors. We compared the hyperreflective bands in the optical coherence tomographic (OCT) images that correspond to structures in the STGD1 photoreceptor inner segments to those in controls. We used adaptive optics scanning light ophthalmoscopy (AO-SLO) to study the distribution of cones and AO-OCT to evaluate the interface of photoreceptors and retinal pigment epithelium (RPE). We found that the profile of the hyperreflective bands differed dramatically between patients with STGD1 and controls. AO-SLOs showed patches in which cone densities were similar to those in healthy retinas and others in which the cone population was sparse. In regions replete with cones, there was no debris at the photoreceptor-RPE interface. In regions with sparse cones, there was abundant debris. Our results raise the possibility that pharmaceutical means may protect surviving photoreceptors and so mitigate vision loss in patients with STGD1. Full article

Inherited retinal diseases (IRDs) represent a frequent cause of blindness in children and adults. As a consequence of the phenotype and genotype heterogeneity of the disease, it is difficult to have a specific diagnosis without molecular testing. To date, over 340 genes and loci have been associated with IRDs. We present the molecular finding of 191 individuals with IRD, analyzed by targeted next-generation sequencing (NGS). For 67 of them, we performed a family segregation study, considering a total of 126 relatives. A total of 359 variants were identified, 44 of which were novel. Genetic diagnostic yield was 41%. However, after stratifying the patients according to their clinical suspicion, diagnostic yield was higher for well-characterized diseases such as Stargardt disease (STGD), at 65%, and for congenital stationary night blindness 2 (CSNB2), at 64%. Diagnostic yield was higher in the patient group where family segregation analysis was possible (68%) and it was higher in younger (55%) than in older patients (33%). The results of this analysis demonstrated that targeted NGS is an effective method for establishing a molecular genetic diagnosis of IRDs. Furthermore, this study underlines the importance of segregation studies to understand the role of genetic variants with unknow pathogenic role. Full article