Dyslipidemia in age-related macular degeneration

Application of mendelian randomization in ocular diseases: a review

Ocular disorders can significantly lower patients' quality of life and impose an economic burden on families and society. However, for the majority of these diseases, their prevalence and mechanisms are yet unknown, making prevention, management, and therapy challenging. Although connections between exposure factors and diseases can be drawn through observational research, it is challenging to rule out the interference of confounding variables and reverse causation. Mendelian Randomization (MR), a method of research that combines genetics and epidemiology, has its advantage to solve this problem and thus has been extensively utilized in the etiological study of ophthalmic diseases. This paper reviews the implementation of MR in the research of ocular diseases and provides approaches for the investigation of related mechanisms as well as the intervention strategies.

Identify risk factors affecting participation of Turkish women in mammography screening for breast cancer prevention

PURPOSE

Cancer screening is a public health intervention aiming to reduce cancer-caused deaths. This study aims to determine the factors affecting the mammography screening time among women aged 40-69.

METHODS

The micro dataset obtained from the Türkiye Health Survey conducted by the Turkish Statistical Institute (TurkStat) in 2019 and 2022 was used in the present study. Stereotype logistic regression was used to determine the variables affecting mammography screening and period for breast cancer prevention in women in Türkiye.

RESULTS

Given the results achieved from the analysis, it was found that factors such as age, marital status, general health condition, comorbidity, receiving psychosocial support, high blood lipid levels, and performing breast self-examinations affected women's adherence to cancer screening programs.

CONCLUSION

Since adherence to mammography increases with age, it is recommended to pay importance to education for women approaching the age of mammography screening. Educated individuals are expected to have access to multiple sources of information as to cancer and to access this information more easily. In order to gain more insight into the recommended preventive measures and outcomes related to cancer, it is suggested to review policies, which will increase the educational level of women, and provide privileges in the field of education.

Risk Factors of Age-Related Macular Degeneration in a Population-Based Study: Results from SHIP-TREND-1 (Study of Health in Pomerania-TREND-1)

BACKGROUND Age-related macular degeneration (AMD) is the most common cause of visual impairment in the elderly population in industrialized countries. The Study of Health in Pomerania (SHIP) with its cohort SHIP-TREND was designed to investigate risk factors and clinical disorders in the general population of northeast Germany. This work focused on the first follow-up of SHIP-TREND and determined associated modifiable risk factors of AMD. Modifying risk factors is important to slow the progression of early AMD as there is currently no treatment for the late stage of geographic atrophy. Understanding AMD-associated risk factors also plays an important role in the development of therapeutic concepts. MATERIAL AND METHODS Between 2016 and 2019, data were collected from a total of 2507 initially randomly selected subjects from the general population aged 28 to 89 years. Non-mydriatic fundus photography of the right eye was performed in 2489 subjects. Grading of AMD was performed using the Rotterdam classification system. RESULTS We included 1418 gradable fundus photographs in the analysis. The risk of AMD changes increased with age and was positively correlated with HDL cholesterol, fT3, and low educational level. In men, BMI and cigarette smoking were also positively associated with AMD changes. CONCLUSIONS This study emphasizes the consideration of various metabolic pathways for the development of therapeutic concepts.

Retinal microcirculation: A window into systemic circulation and metabolic disease

The retinal microcirculation system constitutes a unique terminal vessel bed of the systemic circulation, and its perfusion status is directly associated with the neural function of the retina. This vascular network, essential for nourishing various layers of the retina, comprises two primary microcirculation systems: the retinal microcirculation and the choroidal microcirculation, with each system supplying blood to distinct retinal layers and maintaining the associated neural function. The blood flow of those capillaries is regulated via different mechanisms. However, a range of internal and external factors can disrupt the normal architecture and blood flow within the retinal microcirculation, leading to several retinal pathologies, including diabetic retinopathy, macular edema, and vascular occlusions. Metabolic disturbances such as hyperglycemia, hypertension, and dyslipidemia are known to modify retinal microcirculation through various pathways. These alterations are observable in chronic metabolic conditions like diabetes, coronary artery disease, and cerebral microvascular disease due to advances in non-invasive or minimally invasive retinal imaging techniques. Thus, examination of the retinal microcirculation can provide insights into the progression of numerous chronic metabolic disorders. This review discusses the anatomy, physiology and pathophysiology of the retinal microvascular system, with a particular emphasis on the connections between retinal microcirculation and systemic circulation in both healthy states and in the context of prevalent chronic metabolic diseases.

PREVALENCE AND RISK FACTORS OF AGE-RELATED MACULAR DEGENERATION FEATURES AMONG PILOTS

PURPOSE

To investigate the prevalence and risk factors of age-related macular degeneration features among pilots of Republic of Korea Air Force.

METHODS

This retrospective, cross-sectional study was performed with a total of 2781 Republic of Korea Air Force pilots who underwent regular medical examinations between 2020 and 2021. Age-related macular degeneration features were determined and graded by fundus photographs. Risk factors were identified with logistic regression analysis in odds ratio (OR) and 95% confidence interval (CI).

RESULTS

The prevalence was 12.9% in the Republic of Korea Air Force pilots and 35.2% in those older than 50 years. Pilots with age-related macular degeneration features were positively associated with age (OR: 1.082, CI: 1.067-1.096, P < 0.001), male sex (OR: 0.229, CI: 0.056-0.939, P = 0.041), smoking (OR: 1.027, CI: 1.008-1.047, P = 0.006), flight time (OR: 1.004, CI: 1.003-1.005, P < 0.001), total cholesterol (OR: 1.004, CI: 1.000-1.007, P = 0.033), and low-density lipoprotein (OR: 1.005, CI: 1.001-1.008, P = 0.011). Aircraft type was also identified as a risk factor (OR: 0.617, CI: 0.460-0.827 for carrier, OR: 0.572, CI: 0.348-0.940 for helicopter, P = 0.002), with fighter pilots having a higher risk than carrier and helicopter pilots. The results were similar for pilots older than 50 years.

CONCLUSION

The prevalence of age-related macular degeneration features in Republic of Korea Air Force pilots was higher than in other general populations studied. Identified risk factors such as flight time and aircraft type suggest potential occupational risk of age-related macular degeneration in aviators.

APOB100 transgenic mice exemplify how the systemic circulation content may affect the retina without altering retinal cholesterol input

Apolipoprotein B (APOB) is a constituent of unique lipoprotein particles (LPPs) produced in the retinal pigment epithelium (RPE), which separates the neural retina from Bruch's membrane (BrM) and choroidal circulation. These LPPs accumulate with age in BrM and contribute to the development of age-related macular degeneration, a major blinding disease. The APOB100 transgenic expression in mice, which unlike humans lack the full-length APOB100, leads to lipid deposits in BrM. Herein, we further characterized APOB100 transgenic mice. We imaged mouse retina in vivo and assessed chorioretinal lipid distribution, retinal sterol levels, retinal cholesterol input, and serum content as well as tracked indocyanine green-bound LPPs in mouse plasma and retina after an intraperitoneal injection. Retinal function and differentially expressed proteins were also investigated. APOB100 transgenic mice had increased serum LDL content and an additional higher density HDL subpopulation; their retinal cholesterol levels (initially decreased) became normal with age. The LPP cycling between the RPE and choroidal circulation was increased. Yet, LPP trafficking from the RPE to the neural retina was limited, and total retinal cholesterol input did not change. There were lipid deposits in the RPE and BrM, and retinal function was impaired. Retinal proteomics provided mechanistic insights. Collectively, our data suggested that the serum LDL/HDL ratio may not affect retinal pathways of cholesterol input as serum LPP load is mainly handled by the RPE, which offloads LPP excess to the choroidal circulation rather than neural retina. Different HDL subpopulations should be considered in studies linking serum LPPs and age-related macular degeneration.

Systemic Dyslipidemia in Age-related Macular Degeneration: An Updated Systematic Review and Meta-analysis

Topic

Though lipid and cholesterol dyshomeostasis is thought to contribute to the pathogenesis of age-related macular degeneration (AMD), there is no consensus regarding which elements of systemic lipid homeostasis are perturbed in AMD. In this systematic review and meta-analysis, an update to that performed by Wang et al in 2016, we characterized serum lipoprotein profiles in patients with AMD and its various stages.

Clinical Relevance

These findings may identify novel therapeutic approaches for AMD, a leading cause of blindness among older adults in the industrialized world.

Methods

We used MEDLINE, Embase, and Web of Science to identify articles from database inception to May 2022 that reported blood/serum levels of lipid subspecies (triglycerides [TGs], total cholesterol [TC], low-density lipoprotein [LDL], and high-density lipoprotein [HDL]) in patients with AMD compared with controls. We meta-analyzed the data by generating multilevel random-effects models using restricted maximum likelihood estimation.

Results

Our updated meta-analysis included 56 studies, almost 3 times as many studies as the 2016 meta-analysis with a total of 308 188 participants. There were no significant differences in serum TG, TC, LDL, or HDL between patients with AMD and non-AMD controls. Given significant heterogeneity, we performed subanalyses specifically in patients with early to intermediate nonexudative AMD, advanced nonexudative AMD, and advanced exudative AMD. Compared with non-AMD controls, patients with early to intermediate nonexudative AMD had significantly lower serum TG (standardized mean difference [SMD]: -0.03; 95% confidence interval [95% CI]: -0.06 to -0.01) and higher serum HDL (SMD: 0.07; 95% CI: 0.04-0.11). Patients with advanced exudative AMD had significantly higher serum LDL (SMD: 0.33; 95% CI: 0.04-0.62) compared with non-AMD controls. There were no other significant differences identified.

Conclusion

We found that there is significant heterogeneity in systemic lipoproteins in patients with AMD compared with non-AMD controls. The specific pattern of lipid dyshomeostasis appeared to be distinct based on AMD stage. These findings highlight both the underlying heterogeneity of AMD as well as the presence of distinct pathophysiological mechanisms involved at different stages or subtypes of AMD and may inform the development of novel therapeutic approaches.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Association of lipid-lowering drugs and antidiabetic drugs with age-related macular degeneration: a meta-analysis in Europeans

BACKGROUND/AIMS

To investigate the association of commonly used systemic medications with prevalent age-related macular degeneration (AMD) in the general population.

METHODS

We included 38 694 adults from 14 population-based and hospital-based studies from the European Eye Epidemiology consortium. We examined associations between the use of systemic medications and any prevalent AMD as well as any late AMD using multivariable logistic regression modelling per study and pooled results using random effects meta-analysis.

RESULTS

Between studies, mean age ranged from 61.5±7.1 to 82.6±3.8 years and prevalence ranged from 12.1% to 64.5% and from 0.5% to 35.5% for any and late AMD, respectively. In the meta-analysis of fully adjusted multivariable models, lipid-lowering drugs (LLD) and antidiabetic drugs were associated with lower prevalent any AMD (OR 0.85, 95% CI=0.79 to 0.91 and OR 0.78, 95% CI=0.66 to 0.91). We found no association with late AMD or with any other medication.

CONCLUSION

Our study indicates a potential beneficial effect of LLD and antidiabetic drug use on prevalence of AMD across multiple European cohorts. Our findings support the importance of metabolic processes in the multifactorial aetiology of AMD.

High-Fat Diet Alters Acylcarnitine Metabolism of the Retina and Retinal Pigment Epithelium/Choroidal Tissues in Laser-Induced Choroidal Neovascularization Rat Models

SCOPE

Choroidal neovascularization (CNV) is age-related macular degeneration's (AMD) main pathological change. High-fat diet (HFD) is associated with a form of CNV; however, the specific mechanism is unclear. Mitochondrial dysfunction, characterized by abnormal acylcarnitine, occurs during metabolic screening of serum or other body tissues in AMD. This study investigates HFD's role in retinal and retinal pigment epithelium (RPE)/choroidal acylcarnitine metabolism in CNV formation.

METHODS AND RESULTS

Chow diet and HFD-BN rats are laser-treated to induce CNV. Acylcarnitine species are quantitatively characterized by ultrahigh-performance liquid chromatography-tandem mass spectrometry. Optical coherence tomography and fundus fluorescein angiography evaluate CNV severity. HFD promotes weight gain, dyslipidemia, and CNV formation. In CNV rats, few medium-chain fatty acids (MCFAs) acylcarnitine in the RPE/choroid are initially affected. When an HFD is administered to these, even MCFA acylcarnitine in the RPE/choroid is found to decline. However, in the retina, odd acylcarnitines are increased, revealing "an opposite" change within the RPE/choroid, accompanied by influencing glycolytic key enzymes. The HFD+CNV group incorporated fewer long-chain acylcarnitines, like C18:2, into the retina than controls.

CONCLUSIONS

HFD hastens choroidal neovascularization. The study comprehensively documented acylcarnitine profiles in a CNV rat model. Acylcarnitine's odd-even and carbon-chain length properties may guide future therapeutics.

The Role of Inflammation in Age-Related Macular Degeneration-Therapeutic Landscapes in Geographic Atrophy

Age-related macular degeneration (AMD) is the leading cause of vision loss and visual impairment in people over 50 years of age. In the current therapeutic landscape, intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapies have been central to the management of neovascular AMD (also known as wet AMD), whereas treatments for geographic atrophy have lagged behind. Several therapeutic approaches are being developed for geographic atrophy with the goal of either slowing down disease progression or reversing sight loss. Such strategies target the inflammatory pathways, complement cascade, visual cycle or neuroprotective mechanisms to slow down the degeneration. In addition, retinal implants have been tried for vision restoration and stem cell therapies for potentially a dual purpose of slowing down the degeneration and restoring visual function. In particular, therapies focusing on the complement pathway have shown promising results with the FDA approved pegcetacoplan, a complement C3 inhibitor, and avacincaptad pegol, a complement C5 inhibitor. In this review, we discuss the mechanisms of inflammation in AMD and outline the therapeutic landscapes of atrophy AMD. Improved understanding of the various pathway components and their interplay in this complex neuroinflammatory degeneration will guide the development of current and future therapeutic options, such as optogenetic therapy.

Systemic Metabolomics in a Framework of Genetics and Lifestyle in Age-Related Macular Degeneration

Insights into the pathogenesis of age-related macular degeneration (AMD), a leading cause of blindness, point towards a complex interplay of genetic and lifestyle factors triggering various systemic pathways. This study aimed to characterize metabolomic profiles for AMD and to evaluate their position in the trias with genetics and lifestyle. This study included 5923 individuals from five European studies. Blood metabolomics were assessed using a nuclear magnetic resonance platform of 146 metabolites. Associations were studied using regression analyses. A genetic risk score (GRS) was calculated using β-values of 49 AMD variants, a lifestyle risk score (LRS) using smoking and diet data, and a metabolite risk score (MRS) using metabolite values. We identified 61 metabolites associated with early-intermediate AMD, of which 94% were lipid-related, with higher levels of HDL-subparticles and apolipoprotein-A1, and lower levels of VLDL-subparticles, triglycerides, and fatty acids (false discovery rate (FDR) p-value < 1.4 × 10^-2). Late AMD was associated with lower levels of the amino acids histidine, leucine, valine, tyrosine, and phenylalanine, and higher levels of the ketone bodies acetoacetate and 3-hydroxybutyrate (FDR p-value < 1.5 × 10^-3). A favorable lifestyle characterized by a healthy diet was associated with higher levels of amino acids and lower levels of ketone bodies, while an unfavorable lifestyle, including smoking, showed opposite effects (FDR p-value < 2.7 × 10^-2). The MRS mediated 5% of the effect of the GRS and 20% of that of the LRS on late AMD. Our findings show that metabolomic profiles differ between AMD stages and show that blood metabolites mostly reflect lifestyle. The severity-specific profiles spur further interest into the systemic effects related to disease conversion.

Association between Antihyperlipidemic Agent Use and Age-Related Macular Degeneration in Patients with Hyperlipidemia: A Population-Based Retrospective Cohort Study

Several studies have indicated that lipoproteins might contribute to the pathogenesis of age-related macular degeneration (AMD). In this population-based retrospective cohort study, patients with hyperlipidemia were divided into two groups (study groups I and II) based on whether or not they were receiving antihyperlipidemic agents. The comparison group included patients without hyperlipidemia who were randomly selected and matched with study group II patients. A Cox proportional hazard model was used to evaluate the risk of AMD among the groups. Patients with hyperlipidemia receiving antihyperlipidemic agents (study group I, n = 15,482) had a significantly increased AMD risk (adjusted hazard ratio (HR) = 1.23, 95% confidence interval (CI) = 1.04-1.45) compared to those not receiving antihyperlipidemic agents (study group II, n = 15,482). However, with an increase in cumulative exposure, a reduced risk of AMD was observed in patients using a defined daily dose of more than 721, with an adjusted HR of 0.34 (95% CI = 0.22-0.53, p < 0.001). Additionally, the adjusted HR of AMD for study group II was 1.40 (95% CI = 1.20-1.63, p < 0.001) relative to the comparison group (n = 61,928). In conclusion, the study results indicated that patients with hyperlipidemia have a higher AMD risk than patients without hyperlipidemia. Furthermore, patients with hyperlipidemia who received antihyperlipidemic agents had a significantly increased AMD risk. However, a dose-dependent reduction in the risk of AMD was observed in patients with hyperlipidemia using statins or/and fibrates.

The Essential Role of Light-Induced Autophagy in the Inner Choroid/Outer Retinal Neurovascular Unit in Baseline Conditions and Degeneration

The present article discusses the role of light in altering autophagy, both within the outer retina (retinal pigment epithelium, RPE, and the outer segment of photoreceptors) and the inner choroid (Bruch's membrane, BM, endothelial cells and the pericytes of choriocapillaris, CC). Here autophagy is needed to maintain the high metabolic requirements and to provide the specific physiological activity sub-serving the process of vision. Activation or inhibition of autophagy within RPE strongly depends on light exposure and it is concomitant with activation or inhibition of the outer segment of the photoreceptors. This also recruits CC, which provides blood flow and metabolic substrates. Thus, the inner choroid and outer retina are mutually dependent and their activity is orchestrated by light exposure in order to cope with metabolic demand. This is tuned by the autophagy status, which works as a sort of pivot in the cross-talk within the inner choroid/outer retina neurovascular unit. In degenerative conditions, and mostly during age-related macular degeneration (AMD), autophagy dysfunction occurs in this area to induce cell loss and extracellular aggregates. Therefore, a detailed analysis of the autophagy status encompassing CC, RPE and interposed BM is key to understanding the fine anatomy and altered biochemistry which underlie the onset and progression of AMD.

Self-rated eyesight among healthy older Australians: Baseline results of the ASPREE Longitudinal Study of Older Persons

BACKGROUND

We aimed to describe the self-reported level of eyesight amongst a cohort of relatively healthy older Australian adults, and to investigate associations between poorer self-rated eyesight and demographic, health, and functional characteristics METHODS: The ASPirin in Reducing Events in the Elderly (ASPREE) Longitudinal Study of Older Persons (ALSOP) study was embedded in a multisite trial which recruited independently living Australians from general practices (2010-2014). Self-rated eyesight was recorded on a paper-based questionnaire as Excellent, Good, Fair, Poor, Very poor, or Completely blind at the baseline study wave RESULTS: Data from 14 592 participants (aged 70-95 years, 54.61% female) were included in this cross-sectional analysis. Eighty percent of participants reported excellent or good eyesight (n = 11 677). People with complete blindness were precluded from enrolling but 299 participants (2.0%) reported poor or very poor eyesight, and 2616 rated their eyesight as fair (17.9%). Lower levels of eyesight were associated with being older, female, fewer years of formal education, a primary language other than English, smoking, and self-reported macular degeneration, glaucoma, retinopathy, cataracts, and hearing problems (each p ≤ 0.021). People with lower levels of eyesight had a higher number of falls, frailty characteristics, and depressive symptoms, and lower mental and physical health functioning scores (each p < 0.001) CONCLUSIONS: Whilst most of these healthy older Australians reported good or excellent eyesight, a notable minority reported poor or very poor eyesight, and this was associated with a range of poorer health measures. These findings support the need for additional resources to prevent vision loss and associated sequelae.

Vitreous Fatty Amides and Acyl Carnitines Are Altered in Intermediate Age-Related Macular Degeneration

Purpose

Age-related macular degeneration (AMD) is the leading cause of visual impairment worldwide. In this study, we aimed to investigate the vitreous humor metabolite profiles of patients with intermediate AMD using untargeted metabolomics.

Methods

We performed metabolomics using high-resolution liquid chromatography mass spectrometry on the vitreous humor of 31 patients with intermediate AMD and 30 controls who underwent vitrectomy for epiretinal membrane with or without cataract surgery. Univariate analyses after false discovery rate correction were performed to discriminate the metabolites and identify the significant metabolites of intermediate AMD. For biologic interpretation, enrichment and pathway analysis were conducted using MetaboAnalyst 5.0.

Results

Of the 858 metabolites analyzed in the vitreous humor, 258 metabolites that distinguished patients with AMD from controls were identified (P values < 0.05). Ascorbic acid and uric acid levels increased in the AMD group (all P values < 0.05). The acyl carnitines, such as acetyl L-carnitine (1.37-fold), and fatty amides, such as anandamide (0.9-fold) and docosanamide (0.67-fold), were higher in patients with intermediate AMD. In contrast, nicotinamide (-0.55-fold), and succinic acid (-1.69-fold) were lower in patients with intermediate AMD. The metabolic pathway related oxidation of branched chain fatty acids and carnitine synthesis showed enrichment.

Conclusions

Multiple metabolites related to fatty amides and acyl carnitine were found to be increased in the vitreous humor of patients with intermediate AMD, whereas succinic acid and nicotinamide were reduced, suggesting that altered metabolites related to fatty amides and acyl carnitines and energy metabolism may be implicated in the etiology of AMD.

New insight of metabolomics in ocular diseases in the context of 3P medicine

Metabolomics refers to the high-through untargeted or targeted screening of metabolites in biofluids, cells, and tissues. Metabolome reflects the functional states of cells and organs of an individual, influenced by genes, RNA, proteins, and environment. Metabolomic analyses help to understand the interaction between metabolism and phenotype and reveal biomarkers for diseases. Advanced ocular diseases can lead to vision loss and blindness, reducing patients' quality of life and aggravating socio-economic burden. Contextually, the transition from reactive medicine to the predictive, preventive, and personalized (PPPM / 3P) medicine is needed. Clinicians and researchers dedicate a lot of efforts to explore effective ways for disease prevention, biomarkers for disease prediction, and personalized treatments, by taking advantages of metabolomics. In this way, metabolomics has great clinical utility in the primary and secondary care. In this review, we summarized much progress achieved by applying metabolomics to ocular diseases and pointed out potential biomarkers and metabolic pathways involved to promote 3P medicine approach in healthcare.

Pharmacometabolomics for the Study of Lipid-Lowering Therapies: Opportunities and Challenges

Lipid-lowering therapies are widely used to prevent the development of atherosclerotic cardiovascular disease (ASCVD) and related mortality worldwide. "Omics" technologies have been successfully applied in recent decades to investigate the mechanisms of action of these drugs, their pleiotropic effects, and their side effects, aiming to identify novel targets for future personalized medicine with an improvement of the efficacy and safety associated with the treatment. Pharmacometabolomics is a branch of metabolomics that is focused on the study of drug effects on metabolic pathways that are implicated in the variation of response to the treatment considering also the influences from a specific disease, environment, and concomitant pharmacological therapies. In this review, we summarized the most significant metabolomic studies on the effects of lipid-lowering therapies, including the most commonly used statins and fibrates to novel drugs or nutraceutical approaches. The integration of pharmacometabolomics data with the information obtained from the other "omics" approaches could help in the comprehension of the biological mechanisms underlying the use of lipid-lowering drugs in view of defining a precision medicine to improve the efficacy and reduce the side effects associated with the treatment.

Genome-wide association study and identification of systemic comorbidities in development of age-related macular degeneration in a hospital-based cohort of Han Chinese

Background: Age-related macular degeneration (AMD) is the main cause of severe vision loss in elderly populations of the developed world with limited therapeutic medications available. It is a multifactorial disease with a strong genetic susceptibility which exhibits the differential genetic landscapes among different ethnic groups. Methods: To investigate the Han Chinese-specific genetic variants for AMD development and progression, we have presented a genome-wide association study (GWAS) on 339 AMD cases and 3,390 controls of a Han Chinese population recruited from the Taiwan Precision Medicine Initiative (TPMI). Results: In this study, we have identified several single nucleotide polymorphisms (SNPs) significantly associated with AMD, including rs10490924, rs3750848, and rs3750846 in the ARMS2 gene, and rs3793917, rs11200638, and rs2284665 in the HTRA1 gene, in which rs10490924 was highly linked to the other variants based upon linkage disequilibrium analysis. Moreover, certain systemic comorbidities, including chronic respiratory diseases and cerebrovascular diseases, were also confirmed to be independently associated with AMD. Stratified analysis revealed that both non-exudative and exudative AMD were significantly correlated with these risk factors. We also found that homozygous alternate alleles of rs10490924 could lead to an increased risk of AMD incidence compared to homozygous references or heterozygous alleles in the cohorts of chronic respiratory disease, cerebrovascular disease, hypertension, and hyperlipidemia. Ultimately, we established the SNP models for AMD risk prediction and found that rs10490924 combined with the other AMD-associated SNPs identified from GWAS improved the prediction model performance. Conclusion: These results suggest that genetic variants combined with the comorbidities could effectively identify any potential individuals at a high risk of AMD, thus allowing for both early prevention and treatment.

Artificial Intelligence Analysis of Biofluid Markers in Age-Related Macular Degeneration: A Systematic Review

This systematic review explores the use of artificial intelligence (AI) in the analysis of biofluid markers in age-related macular degeneration (AMD). We detail the accuracy and validity of AI in diagnostic and prognostic models and biofluid markers that provide insight into AMD pathogenesis and progression. This review was conducted in accordance with the Preferred Reporting Items for a Systematic Review and Meta-analysis guidelines. A comprehensive search was conducted across 5 electronic databases including Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, EMBASE, Medline, and Web of Science from inception to July 14, 2021. Studies pertaining to biofluid marker analysis using AI or bioinformatics in AMD were included. Identified studies were assessed for risk of bias and critically appraised using the Joanna Briggs Institute Critical Appraisal tools. A total of 10,264 articles were retrieved from all databases and 37 studies met the inclusion criteria, including 15 cross-sectional studies, 15 prospective cohort studies, five retrospective cohort studies, one randomized controlled trial, and one case–control study. The majority of studies had a general focus on AMD (58%), while neovascular AMD (nAMD) was the focus in 11 studies (30%), and geographic atrophy (GA) was highlighted by three studies. Fifteen studies examined disease characteristics, 15 studied risk factors, and seven guided treatment decisions. Altered lipid metabolism (HDL-cholesterol, total serum triglycerides), inflammation (c-reactive protein), oxidative stress, and protein digestion were implicated in AMD development and progression. AI tools were able to both accurately differentiate controls and AMD patients with accuracies as high as 87% and predict responsiveness to anti-VEGF therapy in nAMD patients. Use of AI models such as discriminant analysis could inform prognostic and diagnostic decision-making in a clinical setting. The identified pathways provide opportunity for future studies of AMD development and could be valuable in the advancement of novel treatments.

Neuroprotection for Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness worldwide. Early to intermediate AMD is characterized by the accumulation of lipid- and protein-rich drusen. Late stages of the disease are characterized by the development of choroidal neovascularization, termed "exudative" or "neovascular AMD," or retinal pigment epithelium (RPE) cell and photoreceptor death, termed "geographic atrophy" (GA) in advanced nonexudative AMD. Although we have effective treatments for exudative AMD in the form of anti-VEGF agents, they have no role for patients with GA. Neuroprotection strategies have emerged as a possible way to slow photoreceptor degeneration and vision loss in patients with GA. These approaches include reduction of oxidative stress, modulation of the visual cycle, reduction of toxic molecules, inhibition of pathologic protein activity, prevention of cellular apoptosis or programmed necrosis (necroptosis), inhibition of inflammation, direct activation of neurotrophic factors, delivery of umbilical tissue-derived cells, and RPE replacement. Despite active investigation in this area and significant promise based on preclinical studies, many clinical studies have not yielded successful results. We discuss selected past and current neuroprotection trials for AMD, highlight the lessons learned from these past studies, and discuss our perspective regarding remaining questions that must be answered before neuroprotection can be successfully applied in the field of AMD research.

Novel Epigenetic Clock Biomarkers of Age-Related Macular Degeneration

Age-Related Macular Degeneration (AMD) is a bilateral ocular condition resulting in irreversible vision impairment caused by the progressive loss of photoreceptors in the macula, a region at the center of the retina. The progressive loss of photoreceptor is a key feature of dry AMD but not always wet AMD, though both forms of AMD can lead to loss of vision. Regression-based biological age clocks are one of the most promising biomarkers of aging but have not yet been used in AMD. Here we conducted analyses to identify regression-based biological age clocks for the retina and explored their use in AMD using transcriptomic data consisting of a total of 453 retina samples including 105 Minnesota Grading System (MGS) level 1 samples, 175 MGS level 2, 112 MGS level 3 and 61 MGS level 4 samples, as well as 167 fibroblast samples. The clocks yielded good separation among AMD samples with increasing severity score viz., MGS1-4, regardless of whether clocks were trained in retina tissue, dermal fibroblasts, or in combined datasets. Clock application to cultured fibroblasts, embryonic stem cells, and induced Pluripotent Stem Cells (iPSCs) were consistent with age reprograming in iPSCs. Moreover, clock application to in vitro neuronal differentiation suggests broader applications. Interesting, many of the age clock genes identified include known targets mechanistically linked to AMD and aging, such as GDF11, C16ORF72, and FBN2. This study provides new observations for retina age clocks and suggests new applications for monitoring in vitro neuronal differentiation. These clocks could provide useful markers for AMD monitoring and possible intervention, as well as potential targets for in vitro screens.

Pathophysiology of Age-Related Macular Degeneration: Implications for Treatment

Age-related macular degeneration (AMD) is a complex, multifactorial, progressive retinal disease that affects millions of people worldwide and has become the leading cause of visual impairment in developed countries. The disease etiopathogenesis is not understood fully, although many triggers and processes that lead to dysfunction and degeneration of the retinal pigment epithelium (RPE) have already been identified. Thus, the lack of cellular control of oxidative stress, altered proteostasis, dysfunction of lipid homeostasis, and mitochondrial dysfunction form an internal feedback loop that causes the RPE to fail and allows accumulation of abnormal misfolded proteins and abnormal lipids that will form drusen. An inadequate antioxidant response, deficits in autophagy mechanisms, and dysregulation of the extracellular matrix (ECM) help to increase the deposition of abnormal drusen material over time. The drusen then act as inflammatory centers that trigger chronic inflammation of the subretinal space in which microglia and recruited macrophages are also involved, and where the complement system is a key component. Choriocapillaris degeneration and nutritional influences are also classic elements recognized in the AMD pathophysiology. The genetic component of the disease is embodied in the recognition of the described risk or protective polymorphisms of some complement and ECM related genes (mainly CFH and ARMS2/HTRA1). Thus, carriers of the risk haplotype at ARMS2/HTRA1 have a higher risk of developing late AMD at a younger age. Finally, gut microbiota and epigenetics may play a role in modulating the progression to advanced AMD with the presence of local inflammatory conditions. Because of multiple implicated processes, different complex combinations of treatments will probably be the best option to obtain the best visual results; they in turn will differ depending on the type and spectrum of disease affecting individual patients or the disease stage in each patient at a specific moment. This will undoubtedly lead to personalized medicine for control and hopefully find a future cure. This necessitates the continued unraveling of all the processes involved in the pathogenesis of AMD that must be understood to devise the combinations of treatments for different concurrent or subsequent problems.