Geographic atrophy: pathophysiology and current therapeutic strategies

Structural en face optical coherence tomography in neovascular and nonneovascularage-related macular degeneration: Use and utility in clinical practice

Age-related macular degeneration (AMD) is a leading cause of blindness and visual impairment worldwide. Structural en face optical coherence tomography (OCT) is an innovative imaging technology that has recently attracted interest because of its potential for assessing AMD features. We conducted a comprehensive review of its application in AMD. In neovascular AMD, structural en face OCT can detect exudative activity, monitor the neovascularization area, study the choroid in polypoidal choroidal vasculopathy, and visualize neovascular membranes in pigment epithelial detachments. Moreover, in nonneovascular AMD, this study provides details on geographic atrophy and drusen, the identification of intraretinal retinal pigment epithelium migration, and the detection of different patterns of outer retinal tubulations. Our study revealed that structural en face OCT can provide relevant information on patients with AMD.

Multi-class classification of central and non-central geographic atrophy using Optical Coherence Tomography

Purpose

To develop and validate deep learning (DL)-based models for classifying geographic atrophy (GA) subtypes using Optical Coherence Tomography (OCT) scans across four clinical classification tasks.

Design

Retrospective comparative study evaluating three DL architectures on OCT data with two experimental approaches.

Subjects

455 OCT volumes (258 Central GA [CGA], 74 Non-Central GA [NCGA], 123 no GA [NGA]) from 104 patients at Atrium Health Wake Forest Baptist. For GA versus age-related macular degeneration (AMD) classification, we supplemented our dataset with AMD cases from four public repositories.

Methods

We implemented ResNet50, MobileNetV2, and Vision Transformer (ViT-B/16) architectures using two approaches: (1) utilizing all B-scans within each OCT volume and (2) selectively using B-scans containing foveal regions. Models were trained using transfer learning, standardized data augmentation, and patient-level data splitting (70:15:15 ratio) for training, validation, and testing.

Main Outcome Measures

Area under the receiver operating characteristic curve (AUC-ROC), F1 score, and accuracy for each classification task (CGA vs. NCGA, CGA vs. NCGA vs. NGA, GA vs. NGA, and GA vs. other forms of AMD).

Results

ViT-B/16 consistently outperformed other architectures across all classification tasks. For CGA versus NCGA classification, ViT-B/16 achieved an AUC-ROC of 0.728±0.083 and accuracy of 0.831±0.006 using selective B-scans. In GA versus NGA classification, ViT-B/16 attained an AUC-ROC of 0.950±0.002 and accuracy of 0.873±0.012 with selective B-scans. All models demonstrated exceptional performance in distinguishing GA from other AMD forms (AUC-ROC>0.998). For multi-class classification, ViT-B/16 achieved an AUC-ROC of 0.873±0.003 and accuracy of 0.751±0.002 using selective B-scans.

Conclusions

Our DL approach successfully classifies GA subtypes with clinically relevant accuracy. ViT-B/16 demonstrates superior performance due to its ability to capture spatial relationships between atrophic regions and the foveal center. Focusing on B-scans containing foveal regions improved diagnostic accuracy while reducing computational requirements, better aligning with clinical practice workflows.

Diet, Mitochondrial Dysfunction, Vascular Endothelial Damage, and the Microbiome: Drivers of Ocular Degenerative and Inflammatory Diseases

There is abundant evidence in medical literature that Western diet and lifestyle drive the cellular and metabolic processes which underlie chronic non-communicable diseases. However, non-pharmaceutical interventions, which focus on nutrition, the microbiome and lifestyle, to prevent non-communicable diseases are not part of mainstream treatment, for a variety of reasons. Lack of progress in stemming the rise in chronic non-communicable diseases can be attributed to the current 'downstream' medical paradigm which is focused on treating disease and symptoms, rather than preventing disease via an 'upstream' approach, which looks at cause and process. Metabolic abnormalities and obesity have previously been noted as correlated with common chronic ophthalmic conditions such as age related macular degeneration (AMD), glaucoma, ocular inflammation, diabetic retinopathy and retinal vascular occlusive disease. These are ocular manifestations of an underlying common cause. The aim of this paper, using an ophthalmic context, is to provide an overview of the cellular pathophysiological mechanisms that underlie chronic non-communicable diseases, including ophthalmic diseases, and to draw the links between diet and lifestyle, the microbiome and chronic non-communicable diseases.

Features that distinguish age-related macular degeneration from aging

Age-related macular degeneration (AMD) is a complex, multifactorial retinal degenerative disease that is influenced by both genetic and environmental factors. However, the strongest risk factor for AMD is advanced age. Several physiological processes are observed in aging tissues including a low level of chronic inflammation (inflammaging), changed lipid and energy metabolism, and senescence. Nevertheless, whereas everyone ages, only a subset of the population develops AMD. The purpose of this review is to delineate the differences on a cellular and molecular level between natural aging changes and those observed in AMD. We provide a unique perspective on how genetic and environmental components modulate aging in the eye, as well as the specific role of the aging RPE and retina in the pathogenesis of AMD. Topics discussed include the mechanism of aging and its relation to the mechanism of AMD, current animal models that can be used to recapitulate some aspects of the pathology, and potential interventions that shift the balance towards healthy aging and therefore attenuate, prevent or delay the initiation of the disease.

Bridging the gap of vision restoration

Retinitis pigmentosa (RP) and Age-Related Macular Degeneration (AMD) are similar in that both result in photoreceptor degeneration leading to permanent progressive vision loss. This affords the possibility of implementing vision restoration techniques, where light signaling is restored to spared retinal circuitry to recreate vision. There are far more AMD patients (Wong et al., 2014), yet more resources have been put towards researching and developing vision restoration strategies for RP despite it rarity, because of the tractability of RP disease models. The hope is that these therapies will extend to the AMD population, however, many questions remain about how the implementation of prosthetic or optogenetic vision restoration technologies will translate between RP and AMD patients. In this review, we discuss the difference and similarities of RP and AMD with a focus on aspects expected to impact vision restoration strategies, and we identify key gaps in knowledge needed to further improve vision restoration technologies for a broad patient population.

Gene Therapies in Clinical Development to Treat Retinal Disorders

Gene therapies have emerged as promising treatments in clinical development for various retinal disorders, offering hope to patients with inherited degenerative eye conditions. Several gene therapies have already shown remarkable success in clinical trials, with significant improvements observed in visual acuity and the preservation of retinal function. A multitude of gene therapies have now been delivered safely in human clinical trials for a wide range of inherited retinal disorders but there are some gaps in the reported trial data. Some of the most exciting treatment options are not under peer review and information is only available in press release form. Whilst many trials appear to have delivered good outcomes of safety, others have failed to meet primary endpoints and therefore not proceeded to phase III. Despite this, such trials have enabled researchers to learn how best to assess and monitor patient outcomes, which will guide future trials to greater success. In this review, we consider recent and ongoing clinical trials for a variety of potential retinal gene therapy treatments and discuss the positive and negative issues related to these trials. We discuss the treatment potential following clinical trials as well as the potential risks of some treatments under investigation. As these therapies continue to advance through rigorous testing and regulatory approval processes, they hold the potential to revolutionise the landscape of retinal disorder treatments, providing renewed vision and enhancing the quality of life for countless individuals worldwide.

Circulating Anti-Endothelial Cell Antibodies in Patients with Geographic Atrophy Related to Dry Age-Related Macular Degeneration

Background and Objectives: Age-related macular degeneration (AMD) is one of the leading causes of central vision loss among elderly patients, and its dry form accounts for the majority of cases. Although several causes and mechanisms for the development and progression of AMD have previously been identified, the pathogenesis of this complex disease is still not entirely understood. As inflammation and immune system involvement are strongly suggested to play a central role in promoting the degenerative process and stimulating the onset of complications, we aimed to analyze the frequency of serum anti-retinal (ARAs) and anti-endothelial cell antibodies (AECAs) in patients with dry AMD and to determine their relationship with the clinical features of the disease, notably the area of geographic atrophy (GA). Materials and Methods: This study included 41 patients with advanced-stage dry AMD and 50 healthy controls without AMD, matched for gender and age. ARAs were detected by indirect immunofluorescence using monkey retina as an antigen substrate, and the presence of AECAs was determined using cultivated human umbilical vein endothelial cells and primate skeletal muscle. Results: ARAs were detected in 36 (87.8%) AMD patients (titers ranged from 1:20 to 1:320) and in 16 (39.0%) (titers ranged from 1:10 to 1:40) controls (p = 0.0000). Twenty of the forty-one patients (48.8%) were positive for AECAs, while in the control group, AECAs were present only in five sera (10.0%). The titers of AECAs in AMD patients ranged from 1:100 to 1:1000, and in the control group, the AECA titers were 1:100 (p = 0.0001). There were no significant correlations between the presence of AECAs and disease activity. Conclusions: This study demonstrates a higher prevalence of circulating AECAs in patients with dry AMD; however, no correlation was found between the serum levels of these autoantibodies and the area of GA.

Epigenetic Switches in Retinal Homeostasis and Target for Drug Development

Retinal homeostasis, a tightly regulated process maintaining the functional integrity of the retina, is vital for visual function. Emerging research has unveiled the critical role of epigenetic regulation in controlling gene expression patterns during retinal development, maintenance, and response to mutational loads and injuries. Epigenetic switches, including DNA methylation, histone modifications, and non-coding RNAs, play pivotal roles in orchestrating retinal gene expression and cellular responses through various intracellular, extracellular, and environmental modulators. This review compiles the current knowledge on epigenetic switches in retinal homeostasis, providing a deeper understanding of their impact on retinal structural integrity and function and using them as potential targets for therapeutic interventions.