Photoreceptor Layer Thinning Is an Early Biomarker for Age-Related Macular Degeneration: Epidemiologic and Genetic Evidence from UK Biobank OCT Data

A deep learning approach to explore the association of age-related macular degeneration polygenic risk score with retinal optical coherence tomography: A preliminary study

PURPOSE

Age-related macular degeneration (AMD) is a complex eye disorder affecting millions worldwide. This article uses deep learning techniques to investigate the relationship between AMD, genetics and optical coherence tomography (OCT) scans.

METHODS

The cohort consisted of 332 patients, of which 235 were diagnosed with AMD and 97 were controls with no signs of AMD. The genome-wide association studies summary statistics utilized to establish the polygenic risk score (PRS) in relation to AMD were derived from the GERA European study. A PRS estimation based on OCT volumes for both eyes was performed using a proprietary convolutional neural network (CNN) model supported by machine learning models. The method's performance was assessed using numerical evaluation metrics, and the Grad-CAM technique was used to evaluate the results by visualizing the features learned by the model.

RESULTS

The best results were obtained with the CNN and the Extra Tree regressor (MAE = 0.55, MSE = 0.49, RMSE = 0.70, R2 = 0.34). Extending the feature vector with additional information on AMD diagnosis, age and smoking history improved the results slightly, with mainly AMD diagnosis used by the model (MAE = 0.54, MSE = 0.44, RMSE = 0.66, R2 = 0.42). Grad-CAM heatmap evaluation showed that the model decisions rely on retinal morphology factors relevant to AMD diagnosis.

CONCLUSION

The developed method allows an efficient PRS estimation from OCT images. A new technique for analysing the association of OCT images with PRS of AMD, using a deep learning approach, may provide an opportunity to discover new associations between genotype-based AMD risk and retinal morphology.

Serum metabolite biomarkers for the early diagnosis and monitoring of age-related macular degeneration

INTRODUCTION

Age-related macular degeneration (AMD) is a leading cause of irreversible blindness worldwide, with significant challenges for early diagnosis and treatment.

OBJECTIVES

To identify new biomarkers that are important for the early diagnosis and monitoring of the severity/progression of AMD.

METHODS

We investigated the diagnostic and monitoring potential of blood metabolites in a cohort of 547 individuals (167 healthy controls, 240 individuals with other eye diseases as eye disease controls, and 140 individuals with AMD) from 2 centers over three phases: discovery phase 1, discovery phase 2, and an external validation phase. The samples were analyzed via a mass spectrometry-based, widely targeted metabolomic workflow. In discovery phases 1 and 2, we built a machine learning algorithm to predict the probability of AMD. In the external validation phase, we further confirmed the performance of the biomarker panel identified by the algorithm. We subsequently evaluated the performance of the identified biomarker panel in monitoring the progression and severity of AMD.

RESULTS

We developed a clinically specific three-metabolite panel (hypoxanthine, 2-furoylglycine, and 1-hexadecyl-2-azelaoyl-sn-glycero-3-phosphocholine) via five machine learning models. The random forest model effectively discriminated patients with AMD from patents in the other two groups and showed acceptable calibration (area under the curve (AUC) = 1.0; accuracy = 1.0) in both discovery phases 1 and 2. An independent validation phase confirmed the diagnostic model's efficacy (AUC = 0.962; accuracy = 0.88). The three-biomarker panel model demonstrated an AUC of 1.0 in differentiating the severity of AMD via RF machine learning, which was consistent across both the discovery and external validation phases. Additionally, the biomarker concentrations remained stable under repeated freeze-thaw cycles (P > 0.05).

CONCLUSIONS

This study reveals distinct metabolite variations in the serum of AMD patients, paving the way for the development of the first routine laboratory test for AMD.

Fundus Image Deep Learning Study to Explore the Association of Retinal Morphology with Age-Related Macular Degeneration Polygenic Risk Score

BACKGROUND

Age-related macular degeneration (AMD) is a complex eye disorder with an environmental and genetic origin, affecting millions worldwide. The study aims to explore the association between retinal morphology and the polygenic risk score (PRS) for AMD using fundus images and deep learning techniques.

METHODS

The study used and pre-processed 23,654 fundus images from 332 subjects (235 patients with AMD and 97 controls), ultimately selecting 558 high-quality images for analysis. The fine-tuned DenseNet121 deep learning model was employed to estimate PRS from single fundus images. After training, deep features were extracted, fused, and used in machine learning regression models to estimate PRS for each subject. The Grad-CAM technique was applied to examine the relationship between areas of increased model activity and the retina's morphological features specific to AMD.

RESULTS

Using the hybrid approach improved the results obtained by DenseNet121 in 5-fold cross-validation. The final evaluation metrics for all predictions from the best model from each fold are MAE = 0.74, MSE = 0.85, RMSE = 0.92, R2 = 0.18, MAPE = 2.41. Grad-CAM heatmap evaluation showed that the model decisions rely on lesion area, focusing mostly on the presence of drusen. The proposed approach was also shown to be sensitive to artifacts present in the image.

CONCLUSIONS

The findings indicate an association between fundus images and AMD PRS, suggesting that deep learning models may effectively estimate genetic risk for AMD from retinal images, potentially aiding in early detection and personalized treatment strategies.

Performance of Automated Machine Learning in Predicting Outcomes of Pneumatic Retinopexy

Purpose

Automated machine learning (AutoML) has emerged as a novel tool for medical professionals lacking coding experience, enabling them to develop predictive models for treatment outcomes. This study evaluated the performance of AutoML tools in developing models predicting the success of pneumatic retinopexy (PR) in treatment of rhegmatogenous retinal detachment (RRD). These models were then compared with custom models created by machine learning (ML) experts.

Design

Retrospective multicenter study.

Participants

Five hundred and thirty nine consecutive patients with primary RRD that underwent PR by a vitreoretinal fellow at 6 training hospitals between 2002 and 2022.

Methods

We used 2 AutoML platforms: MATLAB Classification Learner and Google Cloud AutoML. Additional models were developed by computer scientists. We included patient demographics and baseline characteristics, including lens and macula status, RRD size, number and location of breaks, presence of vitreous hemorrhage and lattice degeneration, and physicians' experience. The dataset was split into a training (n = 483) and test set (n = 56). The training set, with a 2:1 success-to-failure ratio, was used to train the MATLAB models. Because Google Cloud AutoML requires a minimum of 1000 samples, the training set was tripled to create a new set with 1449 datapoints. Additionally, balanced datasets with a 1:1 success-to-failure ratio were created using Python.

Main Outcome Measures

Single-procedure anatomic success rate, as predicted by the ML models. F2 scores and area under the receiver operating curve (AUROC) were used as primary metrics to compare models.

Results

The best performing AutoML model (F2 score: 0.85; AUROC: 0.90; MATLAB), showed comparable performance to the custom model (0.92, 0.86) when trained on the balanced datasets. However, training the AutoML model with imbalanced data yielded misleadingly high AUROC (0.81) despite low F2-score (0.2) and sensitivity (0.17).

Conclusions

We demonstrated the feasibility of using AutoML as an accessible tool for medical professionals to develop models from clinical data. Such models can ultimately aid in the clinical decision-making, contributing to better patient outcomes. However, outcomes can be misleading or unreliable if used naively. Limitations exist, particularly if datasets contain missing variables or are highly imbalanced. Proper model selection and data preprocessing can improve the reliability of AutoML tools.

Financial Disclosures

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

Altered Elastin Turnover, Immune Response, and Age-Related Retinal Thinning in a Transgenic Mouse Model With RPE-Specific HTRA1 Overexpression

Purpose

A single-nucleotide polymorphism in HTRA1 has been linked to age-related macular degeneration (AMD). Here we investigated the potential links between age-related retinal changes, elastin turnover, elastin autoantibody production, and complement C3 deposition in a mouse model with RPE-specific human HTRA1 overexpression.

Methods

HTRA1 transgenic mice and age-matched CD1 wild-type mice were analyzed at 6 weeks and 4, 6, and 12 to 14 months of age using in vivo retinal imaging by optical coherence tomography (OCT) and fundus photography, as well as molecular readouts, focusing on elastin and elastin-derived peptide quantification, antielastin autoantibody, and total Ig antibody measurements and immunohistochemistry to examine elastin, IgG, and C3 protein levels in retinal sections.

Results

OCT imaging indicated thinning of inner nuclear layer as an early phenotype in HTRA1 mice, followed by age and age/genotype-related thinning of the photoreceptor layer, RPE, and total retina. HTRA1 mice exhibited reduced elastin protein levels in the RPE/choroid and increased elastin breakdown products in the retina and serum. A corresponding age-dependent increase of serum antielastin IgG and IgM autoantibodies and total Ig antibody levels was observed. In the RPE/choroid, these changes were associated with an age-related increase of IgG and C3 deposition.

Conclusions

Our results confirm that RPE-specific overexpression of human HTRA1 induces certain AMD-like phenotypes in mice. This includes altered elastin turnover, immune response, and complement deposition in the RPE/choroid in addition to age-related outer retinal and photoreceptor layer thinning. The identification of elastin-derived peptides and corresponding antielastin autoantibodies, together with increased C3 deposition in the RPE/choroid, provides a rationale for an overactive complement system in AMD irrespective of the underlying genetic risk.

Periodontitis and Outer Retinal Thickness: a Cross-Sectional Analysis of the United Kingdom Biobank Cohort

Purpose

Periodontitis, a ubiquitous severe gum disease affecting the teeth and surrounding alveolar bone, can heighten systemic inflammation. We investigated the association between very severe periodontitis and early biomarkers of age-related macular degeneration (AMD), in individuals with no eye disease.

Design

Cross-sectional analysis of the prospective community-based cohort United Kingdom (UK) Biobank.

Participants

Sixty-seven thousand three hundred eleven UK residents aged 40 to 70 years recruited between 2006 and 2010 underwent retinal imaging.

Methods

Macular-centered OCT images acquired at the baseline visit were segmented for retinal sublayer thicknesses. Very severe periodontitis was ascertained through a touchscreen questionnaire. Linear mixed effects regression modeled the association between very severe periodontitis and retinal sublayer thicknesses, adjusting for age, sex, ethnicity, socioeconomic status, alcohol consumption, smoking status, diabetes mellitus, hypertension, refractive error, and previous cataract surgery.

Main Outcome Measures

Photoreceptor layer (PRL) and retinal pigment epithelium-Bruch's membrane (RPE-BM) thicknesses.

Results

Among 36 897 participants included in the analysis, 1571 (4.3%) reported very severe periodontitis. Affected individuals were older, lived in areas of greater socioeconomic deprivation, and were more likely to be hypertensive, diabetic, and current smokers (all P < 0.001). On average, those with very severe periodontitis were hyperopic (0.05 ± 2.27 diopters) while those unaffected were myopic (-0.29 ± 2.40 diopters, P < 0.001). Following adjusted analysis, very severe periodontitis was associated with thinner PRL (-0.55 μm, 95% confidence interval [CI], -0.97 to -0.12; P = 0.022) but there was no difference in RPE-BM thickness (0.00 μm, 95% CI, -0.12 to 0.13; P = 0.97). The association between PRL thickness and very severe periodontitis was modified by age (P < 0.001). Stratifying individuals by age, thinner PRL was seen among those aged 60 to 69 years with disease (-1.19 μm, 95% CI, -1.85 to -0.53; P < 0.001) but not among those aged < 60 years.

Conclusions

Among those with no known eye disease, very severe periodontitis is statistically associated with a thinner PRL, consistent with incipient AMD. Optimizing oral hygiene may hold additional relevance for people at risk of degenerative retinal disease.

Financial Disclosures

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

Inefficacy of anti-VEGF therapy reflected in VEGF-mediated photoreceptor degeneration

Retinal neovascularization (RNV) is primarily driven by vascular endothelial growth factor (VEGF). However, current anti-VEGF therapies are limited by short half-lives and repeated injections, which reduce patient quality of life and increase medical risks. Additionally, not all patients benefit from anti-VEGF monotherapy, and some problems, such as unsatisfactory vision recovery, persist after long-term treatment. In this study, we constructed a recombinant adeno-associated virus (AAV), AAV2-SPLTH, which encodes an anti-VEGF antibody similar to bevacizumab, and assessed its effects in a doxycycline-induced Tet-opsin-VEGFA mouse model of RNV. AAV2-SPLTH effectively inhibited retinal leakage, RNV progression, and photoreceptor apoptosis in a Tet-opsin-VEGF mouse model. However, proteomic sequencing showed that AAV2-SPLTH failed to rescue the expression of phototransduction-related genes, which corresponded to reduced photoreceptor cell numbers. This study suggests that anti-VEGF monotherapy can significantly inhibit RNV to some extent but may not be enough to save visual function in the long term.

Exploring the factors influencing nutritional literacy based on the socioecological model among patients with age-related macular degeneration: a qualitative study from China

OBJECTIVES

Although nutritional support is beneficial to the visual rehabilitation of patients with age-related macular degeneration (AMD), a large gap continues to exist between the relevant guidelines and the actual practices of AMD patients; this gap can be attributed to a lack of nutritional literacy. Therefore, this study explored the factors affecting nutritional literacy among AMD patients.

DESIGN

A qualitative study was carried out based on individual in-person interviews with 15 AMD patients; a semistructured interview guide was used for data collection. The socioecological model (SEM) was employed for data analysis.

SETTING

The Southwest Hospital in Chongqing Province, China.

PARTICIPANTS

A purposive sample of 15 AMD patients was recruited between May and June 2023.

RESULTS

The social ecosystem of patients with AMD has not been positive. At the intrapersonal level, the factors affecting the nutritional literacy of such patients are lack of knowledge, nutrition self-efficacy, economic burdens, dietary preferences and health status. At the interpersonal level, the factors that can influence patients' nutritional literacy are social support and social roles. At the institutional level, the relevant factors are doctor-patient trust and interdisciplinary-team consistency. Finally, at the policy level, a powerful factor is the large gap between policy and implementation.

DISCUSSION

Nutritional literacy focuses on the changes in an individual's knowledge and behaviour concerning nutrition. To inform the development of nutritional-literacy interventions for people with AMD, medical staff should consider multiple perspectives that can remove the barriers to the SEM at all levels.

Association of Genetic Risk for Age-Related Macular Degeneration with Morphological Features of the Retinal Microvascular Network

BACKGROUND

Age-related macular degeneration (AMD) is a multifactorial disease encompassing a complex interaction between aging, environmental risk factors, and genetic susceptibility. The study aimed to determine whether there is a relationship between the polygenic risk score (PRS) in patients with AMD and the characteristics of the retinal vascular network visualized by optical coherence tomography angiography (OCTA).

METHODS

235 patients with AMD and 97 healthy controls were included. We used data from a previous AMD PRS study with the same group. The vascular features from different retina layers were compared between the control group and the patients with AMD. The association between features and PRS was then analyzed using univariate and multivariate approaches.

RESULTS

Significant differences between the control group and AMD patients were found in the vessel diameter distribution (variance: p = 0.0193, skewness: p = 0.0457) and fractal dimension distribution (mean: p = 0.0024, variance: p = 0.0123). Both univariate and multivariate analyses showed no direct and significant association between the characteristics of the vascular network and AMD PRS.

CONCLUSIONS

The vascular features of the retina do not constitute a biomarker of the risk of AMD. We have not identified a genotype-phenotype relationship, and the expression of AMD-related genes is perhaps not associated with the characteristics of the retinal vascular network.

Non-Neovascular Age-Related Macular Degeneration Assessment: Focus on Optical Coherence Tomography Biomarkers

The imagistic evaluation of non-neovascular age-related macular degeneration (AMD) is crucial for diagnosis, monitoring progression, and guiding management of the disease. Dry AMD, characterized primarily by the presence of drusen and retinal pigment epithelium atrophy, requires detailed visualization of the retinal structure to assess its severity and progression. Several imaging modalities are pivotal in the evaluation of non-neovascular AMD, including optical coherence tomography, fundus autofluorescence, or color fundus photography. In the context of emerging therapies for geographic atrophy, like pegcetacoplan, it is critical to establish the baseline status of the disease, monitor the development and expansion of geographic atrophy, and to evaluate the retina's response to potential treatments in clinical trials. The present review, while initially providing a comprehensive description of the pathophysiology involved in AMD, aims to offer an overview of the imaging modalities employed in the evaluation of non-neovascular AMD. Special emphasis is placed on the assessment of progression biomarkers as discerned through optical coherence tomography. As the landscape of AMD treatment continues to evolve, advanced imaging techniques will remain at the forefront, enabling clinicians to offer the most effective and tailored treatments to their patients.

Inactivation of adenosine receptor 2A suppresses endothelial-to-mesenchymal transition and inhibits subretinal fibrosis in mice

Anti-vascular endothelial growth factor therapy has had a substantial impact on the treatment of choroidal neovascularization (CNV) in patients with neovascular age-related macular degeneration (nAMD), the leading cause of vision loss in older adults. Despite treatment, many patients with nAMD still develop severe and irreversible visual impairment because of the development of subretinal fibrosis. We recently reported the anti-inflammatory and antiangiogenic effects of inhibiting the gene encoding adenosine receptor 2A (Adora2a), which has been implicated in cardiovascular disease. Here, using two mouse models of subretinal fibrosis (mice with laser injury-induced CNV or mice with a deficiency in the very low-density lipoprotein receptor), we found that deletion of Adora2a either globally or specifically in endothelial cells reduced subretinal fibrosis independently of angiogenesis. We showed that Adora2a-dependent endothelial-to-mesenchymal transition contributed to the development of subretinal fibrosis in mice with laser injury-induced CNV. Deficiency of Adora2a in cultured mouse and human choroidal endothelial cells suppressed induction of the endothelial-to-mesenchymal transition. A metabolomics analysis of cultured human choroidal endothelial cells showed that ADORA2A knockdown with an siRNA reversed the increase in succinate because of decreased succinate dehydrogenase B expression under fibrotic conditions. Pharmacological inhibition of ADORA2A with a small-molecule KW6002 in both mouse models recapitulated the reduction in subretinal fibrosis observed in mice with genetic deletion of Adora2a. ADORA2A inhibition may be a therapeutic approach to treat subretinal fibrosis associated with nAMD.

Topical Ophthalmic Liposomes Dual-Modified with Penetratin and Hyaluronic Acid for the Noninvasive Treatment of Neovascular Age-Related Macular Degeneration

Introduction

Since intrinsic ocular barrier limits the intraocular penetration of therapeutic protein through eye drops, repeated intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents are the standard therapy for neovascular age-related macular degeneration (nAMD), which are highly invasive and may cause particular ocular complications, leading to poor patient compliance.

Methods

Using Penetratin (Pen) as the ocular penetration enhancer and hyaluronic acid (HA) as the retina-targeting ligand, a dual-modified ophthalmic liposome (Penetratin hyaluronic acid-liposome/Conbercept, PenHA-Lip/Conb) eye drop was designed to non-invasively penetrate the ocular barrier and deliver anti-VEGF therapeutic agents to the targeted intraocular tissue.

Results

PenHA-Lip effectively penetrates the ocular barrier and targets the retinal pigment epithelium via corneal and non-corneal pathways. After a single topical administration of conbercept-loaded PenHA-Lip (PenHA-Lip/Conb), the intraocular concentration of conbercept peaked at 18.74 ± 1.09 ng/mL at 4 h, which is 11.55-fold higher than unmodified conbercept. In a laser-induced choroidal neovascularization (CNV) mouse model, PenHA-Lip/Conb eye drops three times daily for seven days inhibited CNV formation and progression without any significant tissue toxicity and achieved an equivalent effect to a single intravitreal conbercept injection.

Conclusion

PenHA-Lip efficiently and safely delivered conbercept to the posterior eye segment and may be a promising noninvasive therapeutic option for nAMD.

Phenome- and genome-wide analyses of retinal optical coherence tomography images identify links between ocular and systemic health

The human retina is a multilayered tissue that offers a unique window into systemic health. Optical coherence tomography (OCT) is widely used in eye care and allows the noninvasive, rapid capture of retinal anatomy in exquisite detail. We conducted genotypic and phenotypic analyses of retinal layer thicknesses using macular OCT images from 44,823 UK Biobank participants. We performed OCT layer cross-phenotype association analyses (OCT-XWAS), associating retinal thicknesses with 1866 incident conditions (median 10-year follow-up) and 88 quantitative traits and blood biomarkers. We performed genome-wide association studies (GWASs), identifying inherited genetic markers that influence retinal layer thicknesses and replicated our associations among the LIFE-Adult Study (N = 6313). Last, we performed a comparative analysis of phenome- and genome-wide associations to identify putative causal links between retinal layer thicknesses and both ocular and systemic conditions. Independent associations with incident mortality were detected for thinner photoreceptor segments (PSs) and, separately, ganglion cell complex layers. Phenotypic associations were detected between thinner retinal layers and ocular, neuropsychiatric, cardiometabolic, and pulmonary conditions. A GWAS of retinal layer thicknesses yielded 259 unique loci. Consistency between epidemiologic and genetic associations suggested links between a thinner retinal nerve fiber layer with glaucoma, thinner PS with age-related macular degeneration, and poor cardiometabolic and pulmonary function with a thinner PS. In conclusion, we identified multiple inherited genetic loci and acquired systemic cardio-metabolic-pulmonary conditions associated with thinner retinal layers and identify retinal layers wherein thinning is predictive of future ocular and systemic conditions.

Relationship Between Retinal Layer Thickness and Genetic Susceptibility to Age-Related Macular Degeneration in Asian Populations

Purpose

For OCT retinal thickness measurements to be used as a prodromal age-related macular degeneration (AMD) risk marker, the 3-dimensional (3D) topographic variation of the relationship between genetic susceptibility to AMD and retinal thickness needs to be assessed. We aimed to evaluate individual retinal layer thickness changes and topography at the macula that are associated with AMD genetic susceptibility.

Design

Genetic association study.

Participants

A total of 1579 healthy participants (782 Chinese, 353 Malays, and 444 Indians) from the multiethnic Singapore Epidemiology of Eye Diseases study were included.

Methods

Spectral-domain OCT and automatic segmentation of individual retinal layers were performed to produce 10 retinal layer thickness measurements at each ETDRS subfield, producing 3D topographic information. Age-related macular degeneration genetic susceptibility was represented via single nucleotide polymorphisms (SNPs) and aggregated via whole genome (overall) and pathway-specific age-related macular degeneration polygenic risk score (PRSAMD).

Main Outcome Measures

Associations of individual SNPs, overall PRSAMD, and pathway-specific PRSAMD with retinal thickness were analyzed by individual retinal layer and ETDRS subfield.

Results

CFH rs10922109, ARMS2-HTRA1 rs3750846, and LIPC rs2043085 were the top AMD susceptibility SNPs associated with retinal thickness of individual layers (P < 1.67 × 10-3), all at the central subfield. The overall PRSAMD was most associated with thinner L9 (outer segment photoreceptor/retinal pigment epithelium complex) thickness at the central subfield (β = -0.63 μm; P = 5.45 × 10-9). Pathway-specific PRSAMD for the complement cascade (β = -0.53 μm; P = 9.42 × 10-7) and lipoprotein metabolism (β = -0.05 μm; P = 0.0061) were associated with thinner photoreceptor layers (L9 and L7 [photoreceptor inner/outer segments], respectively) at the central subfield. The mean PRSAMD score was larger among Indians compared with that of the Chinese and had the thinnest thickness at the L9 central subfield (β = -1.00 μm; P = 2.91 × 10-7; R2 = 5.5%). Associations at other retinal layers and ETDRS regions were more heterogeneous.

Conclusions

Overall genetic susceptibility to AMD and the aggregate effects of the complement cascade and lipoprotein metabolism pathway are associated most significantly with L7 and L9 photoreceptor thinning at the central macula in healthy individuals. Photoreceptor thinning has potential to be a prodromal AMD risk marker, and topographic variation should be considered.

Financial Disclosures

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

Discernibility of the Interdigitation Zone (IZ), a Potential Optical Coherence Tomography (OCT) Biomarker for Visual Dysfunction in Aging

PURPOSE

Photoreceptor (PR) outer segments, retinal pigment epithelium apical processes, and inter-PR matrix contribute to the interdigitation zone (IZ) of optical coherence tomography (OCT). We hypothesize that this interface degrades over adulthood, in concert with a delay of rod mediated dark adaptation (RMDA). To explore this idea, we determined IZ discernibility and RMDA in younger and older adults.

METHODS

For this cross-sectional study, eyes of 20 young (20-30 years) and 40 older (≥60 years) participants with normal maculas according to the AREDS 9-step grading system underwent OCT imaging and RMDA testing at 5° superior to the fovea. Custom FIJI plugins enabled analysis for IZ discernibility at 9 eccentricities in 0.5 mm steps on one single horizontal B-scan through the fovea. Locations with discernible IZ met two criteria: visibility on B-scans and a distinct peak on a longitudinal reflectivity profile. The frequency of sites meeting both criteria was compared between both age groups and correlated with rod intercept time (RIT).

RESULTS

The median number of locations with discernible IZ was significantly higher (foveal, 4 vs. 0, p = 0.0099; extra-foveal 6 vs. 0, p < 0.001) in eyes of young (26 ± 3 years) compared to older (73 ± 5 years) participants. For the combined young and older sample, the higher frequency of discernible IZ was correlated with shorter RIT (faster dark adaptation) (rs = -0.56, p < 0.0001). This association was significant within young eyes (rs = -0.54; p = 0.0134) and not within older eyes (rs = -0.29, p = 0.706).

CONCLUSIONS

Results suggest that the interface between outer segments and apical processes degrades in normal aging, potentially contributing to delayed rod-mediated dark adaptation. More research is needed to verify an age-related association between IZ discernibility and rod-mediated dark adaptation. If confirmed in a large sample, IZ discernibility might prove to be a valuable biomarker and predictor for visual function in aging.

MMP9-Responsive Graphene Oxide Quantum Dot-Based Nano-in-Micro Drug Delivery System for Combinatorial Therapy of Choroidal Neovascularization

Age-related macular degeneration (AMD), especially wet AMD with choroidal neovascularization (CNV), commonly causes blindness in older patients and disruption of the choroid followed by second-wave injuries, including chronic inflammation, oxidative stress, and excessive matrix metalloproteinase 9 (MMP9) expression. Increased macrophage infiltrate in parallel with microglial activation and MMP9 overexpression on CNV lesions is shown to contribute to the inflammatory process and then enhance pathological ocular angiogenesis. Graphene oxide quantum dots (GOQDs), as natural antioxidants, exert anti-inflammatory effects and minocycline is a specific macrophage/microglial inhibitor that can suppress both macrophage/microglial activation and MMP9 activity. Herein, an MMP9-responsive GOQD-based minocycline-loaded nano-in-micro drug delivery system (C18PGM) is developed by chemically bonding GOQDs to an octadecyl-modified peptide sequence (C18-GVFHQTVS, C18P) that can be specifically cleaved by MMP9. Using a laser-induced CNV mouse model, the prepared C18PGM shows significant MMP9 inhibitory activity and anti-inflammatory action followed by antiangiogenic effects. Moreover, C18PGM combined with antivascular endothelial growth factor antibody bevacizumab markedly increases the antiangiogenesis effect by interfering with the "inflammation-MMP9-angiogenesis" cascade. The prepared C18PGM shows a good safety profile and no obvious ophthalmic or systemic side effects. The results taken together suggest that C18PGM is an effective and novel strategy for combinatorial therapy of CNV.

Ideal vitamin D and handgrip strength counteracts the risk effect of APOE genotype on dementia: a population-based longitudinal study

BACKGROUND

Higher vitamin D concentrations and grip strength contribute to lower individual-level risk of dementia, while apolipoprotein 4 (APOE e4) genotype carries increases dementia risk, but whether combination of ideal vitamin D and grip strength counteracts the risk effect of dementia related to APOE e4 genotype remains unclear. We aimed to investigate the interactions between vitamin D/grip strength and APOE e4 genotype and their association with dementia.

METHODS

The UK Biobank cohort comprised 165,688 dementia-free participants (aged at least 60 years) for the dementia analysis. Dementia was ascertained using hospital inpatient, mortality, and self-reported data until 2021. Vitamin D and grip strength were collected at baseline and divided into tertiles. APOE genotype was coded as APOE e4 non-carries and APOE e4 carries. Data were analyzed using Cox proportional hazard models and restricted cubic regression splines, with adjusted for known confounders.

RESULTS

Over the follow-up (median: 12.0 years), 3917 participants developed dementia. In women and men, respectively, compared with to the lowest tertile of vitamin D, the HRs (95% CIs) of dementia were lower in the middle [0.86 (0.76-0.97)/0.80 (0.72-0.90)] and the highest tertile [0.81 (0.72-0.90)/0.73 (0.66-0.81)]. Tertiles of grip strength showed similar patterns. In women and men, respectively, participants who had both highest tertile of vitamin D and grip strength was associated with a lower risk of dementia compared to those with both lowest tertile of these two exposures among APOE e4 genotype carries (HR = 0.56, 95% CI 0.42-0.76, and HR = 0.48, 95% CI 0.36-0.64) and APOE e4 genotype non-carries (HR = 0.56, 95% CI 0.38-0.81, and HR = 0.34, 95% CI 0.24-0.47). There were significant additive interactions between lower vitamin D/grip strength and APOE e4 genotype on dementia among women and men.

CONCLUSIONS

Higher vitamin D and grip strength were associated with a lower risk of dementia, and seemed to halve the adverse effects of APOE e4 genotype on dementia. Our findings suggested that vitamin D and grip strength may be imperative for estimating the risks of dementia, especially among APOE e4 genotype carries.

Insights into human health from phenome- and genome-wide analyses of UK Biobank retinal optical coherence tomography phenotypes

The human retina is a complex multi-layered tissue which offers a unique window into systemic health and disease. Optical coherence tomography (OCT) is widely used in eye care and allows the non-invasive, rapid capture of retinal measurements in exquisite detail. We conducted genome- and phenome-wide analyses of retinal layer thicknesses using macular OCT images from 44,823 UK Biobank participants. We performed phenome-wide association analyses, associating retinal thicknesses with 1,866 incident ICD-based conditions (median 10-year follow-up) and 88 quantitative traits and blood biomarkers. We performed genome-wide association analyses, identifying inherited genetic markers which influence the retina, and replicated our associations among 6,313 individuals from the LIFE-Adult Study. And lastly, we performed comparative association of phenome- and genome- wide associations to identify putative causal links between systemic conditions, retinal layer thicknesses, and ocular disease. Independent associations with incident mortality were detected for photoreceptor thinning and ganglion cell complex thinning. Significant phenotypic associations were detected between retinal layer thinning and ocular, neuropsychiatric, cardiometabolic and pulmonary conditions. Genome-wide association of retinal layer thicknesses yielded 259 loci. Consistency between epidemiologic and genetic associations suggested putative causal links between thinning of the retinal nerve fiber layer with glaucoma, photoreceptor segment with AMD, as well as poor cardiometabolic and pulmonary function with PS thinning, among other findings. In conclusion, retinal layer thinning predicts risk of future ocular and systemic disease. Furthermore, systemic cardio-metabolic-pulmonary conditions promote retinal thinning. Retinal imaging biomarkers, integrated into electronic health records, may inform risk prediction and potential therapeutic strategies.

Macular outer nuclear layer, ellipsoid zone and outer photoreceptor segment band thickness, axial length and other determinants

The study aims to assess the thickness of the retinal outer nuclear layer (ONL), ellipsoid zone (EZ) and photoreceptor outer segment (POS) band in various macular regions and its associations with axial length and other parameters. Participants of the Beijing Eye Study 2011 underwent a series of examinations including spectral-domain optical coherence tomography of the macula. The current study included 2213 participants without retinal or optic nerve diseases (age: 61.7 ± 8.4 years; range 50-93 years); axial length: 23.15 ± 0.95 mm; range 18.96-29.15 mm). The ONL (fovea: 98.9 ± 8.8 µm), EZ (fovea: 24.1 ± 0.5 µm) and POS band (fovea: 24.3 ± 3.5 µm) were the thickest (P < 0.001) in the fovea (defined as the thinnest central point), followed by the temporal inner, nasal inner, inferior inner, superior inner, inferior outer, temporal outer, nasal outer, and superior outer region. In multivariable analysis, a thicker retinal ONL was associated (correlation coefficient r: 0.40) with shorter axial length (beta: - 0.14; P < 0.001) and shorter disc-fovea distance (beta: - 0.10; P = 0.001), after adjusting for younger age (beta: - 0.26; P < 0.001), male sex (beta: 0.24; P < 0.001), lower serum cholesterol concentration (beta: - 0.05; P = 0.04), and thicker subfoveal choroidal thickness (beta: 0.08; P < 0.001). The POS thickness increased with shorter axial length (beta: - 0.06; P < 0.001) and shorter optic disc-fovea distance (beta: - 0.05; P = 0.03), after adjusting for younger age (beta: - 0.34; P < 0.001), male sex (beta: 0.15; P < 0.001), and thicker subfoveal choroidal thickness (beta: 0.24; P < 0.001). As a conclusion, the photoreceptor ONL, EZ and POS band vary in thickness between different macular regions and differ in their correlations with axial length, disc-fovea distance, age, sex, and subfoveal choroidal thickness. The ONL thickness decrease with longer axial length and longer disc-fovea distance may point to an axial elongation-associated retinal stretching in the macula.

hPSC-derived RPE transplantation for the treatment of macular degeneration

Macular degeneration (MD) is a group of diseases characterized by irreversible and progressive vision loss. Patients with MD suffer from severely impaired central vision, especially elderly people. Currently, only one type of MD, wet age-related macular degeneration (AMD), can be treated with anti-vascular endothelium growth factor (VEGF) drugs. Other types of MD remain difficult to treat. With the advent of human pluripotent stem cells (hPSCs) and their differentiation into retinal pigmented epithelium (RPE), it is promising to treat patients with MD by transplantation of hPSC-derived RPE into the subretinal space. In this review, the current progress in hPSC-derived RPE transplantation for the treatment of patients with MD is described from bench to bedside, including hPSC differentiation into RPE and the characterization and usage of hPSC-derived RPE for transplantation into patients with MD.

Retinal Pigment Epithelial Abnormality and Choroidal Large Vascular Flow Imbalance Are Associated with Choriocapillaris Flow Deficits in Age-Related Macular Degeneration in Fellow Eyes

Choriocapillaris flow deficits detected on optical coherence tomography angiographs were retrospectively analyzed. In 38 age-related macular degeneration (AMD) fellow eyes, without fundus findings (26 men, 71.7 ± 1.9 years old), and 22 control eyes (11 men, 69.4 ± 1.8), the choriocapillaris flow area (CCFA) ratio and coefficient of variation (CV) of the CCFA ratio (which represented the heterogeneity of the ratio), negatively and positively correlated with age (all p < 0.01), respectively. Moreover, the respective mean values were lower (p = 0.0031) and greater (p = 0.002) in AMD fellow eyes than in the control eyes. The high-risk condition of AMD fellow eyes was defined by a CCFA ratio <58.5%, and the CV of the CCFA ratio ≥0.165 (odds ratio (OR), 5.408; 95% confidence interval (CI): 1.117-21.118, p = 0.035, after adjusting for age and sex) was related to the presence of fundus autofluorescence abnormality (OR, 16.440; 95% CI, 1.262-214.240; p = 0.033) and asymmetrically dilated choroidal large vasculature (OR, 4.176; 95% CI, 1.057-16.503; p = 0.042), after adjusting for age and sex. The presence of fundus autofluorescence abnormality indicated a retinal pigment epithelium (RPE) abnormality. The RPE volume was reduced in the latter eye group, particularly in the thinner choroidal vasculature. In addition to aging, RPE abnormality and choroidal large vascular flow imbalances were associated with exacerbated heterogeneous choriocapillaris flow deficits in AMD fellow eyes without macular neovascularization.

Physiology and pathology of the C3 amplification cycle: A retrospective

The C3 "Tickover" hypothesis, a mechanism whereby the host maintains constant surveillance of potential invading pathogens, targeting them for elimination through amplified C3b generation and C3-dependent effector mechanisms, was proposed by the late Professor Peter Lachmann in 1973. This unique insight came from a combined understanding of the complement system as it was then defined and the nature of the disease process in rare complement deficiencies and complement-driven diseases. In this review, I give a personal perspective of how understanding of "Tickover" has developed in the subsequent 50 years, culminating in the introduction into the clinic of therapeutic agents designed to combat amplification-driven disease.

Short-Term Hyperuricemia Leads to Structural Retinal Changes That Can be Reversed by Serum Uric Acid Lowering Agents in Mice

Purpose

Metabolic disorders have been implicated in ocular diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). Recently, hyperuricemia (HUA) has been proposed as another risk factor for AMD, although no cause-and-effect experimental data have been published. In this study, we investigated whether HUA would initiate AMD or related retinal damages in hyperuricemic mice.

Methods

HUA was induced in male ICR mice by dietary supplements of uric acid and oxonic acid potassium salt, with or without treatments by allopurinol or benzbromarone for various durations. Serum uric acid and angiotensin II concentrations were measured by enzyme-linked immunosorbent assay (ELISA) at regular intervals. The retinal damages were assessed by hematoxylin and eosin staining, immunostaining, and TUNEL assay. The cause-and-effect of HUA was compared among the study groups.

Results

The results showed that the total thickness of photoreceptor inner and outer segments, as well as the thickness of the photoreceptor outer segment alone, were reduced under HUA. Furthermore, HUA elevated serum angiotensin II, which indicated activation of the renin–angiotensin system (RAS), leading to higher matrix metalloproteinase-2 (MMP-2) expression, and glial activation in the ganglion cell layer. HUA also led to the reduction of retinal pigment epithelium gap junction protein connexin-43 and apoptosis. Uric acid lowering agents, allopurinol or benzbromarone, were effective in ameliorating the impairments.

Conclusions

HUA may pose as a causative factor of retinal injuries. The reduction of serum uric acid may reduce the detrimental effects caused by HUA.

A Clinical and Preclinical Assessment of Clinical Trials for Dry Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness for the elderly in high-income countries. Although multivitamin antioxidant nutrients can slow the progression of intermediate "dry" or nonneovascular AMD, no treatment can halt or reverse any stage of dry disease. Multiple biologic pathways have been implicated in AMD pathobiology, including the complement pathway. These pathways have been targeted by various approaches in clinical trials. To date, no treatment has reached their prespecified primary end point in 2 phase III trials, a requirement by the US Food and Drug Administration for a new drug approval. Here, we describe perspectives on the failures and possible successes of various clinical trials that will guide further investigation. These perspectives will also discuss clinical trial design issues to consider in future investigations, and how recent insights into AMD pathobiology might both provide additional explanation for trials not reaching the prespecified primary end points and offer direction for identifying prioritized treatment targets.

Automatic quantification of retinal photoreceptor integrity to predict persistent disease activity in neovascular age-related macular degeneration using deep learning

Purpose

Using deep learning (DL)-based technique, we identify risk factors and create a prediction model for refractory neovascular age-related macular degeneration (nAMD) characterized by persistent disease activity (PDA) in spectral domain optical coherence tomography (SD-OCT) images.

Materials and methods

A total of 671 typical B-scans were collected from 186 eyes of 186 patients with nAMD. Spectral domain optical coherence tomography images were analyzed using a classification convolutional neural network (CNN) and a fully convolutional network (FCN) algorithm to extract six features involved in nAMD, including ellipsoid zone (EZ), external limiting membrane (ELM), intraretinal fluid (IRF), subretinal fluid (SRF), pigment epithelium detachment (PED), and subretinal hyperreflective material (SHRM). Random forest models were probed to predict 1-year disease activity (stable, PDA, and cured) based on the quantitative features computed from automated segmentation and evaluated with cross-validation.

Results

The algorithm to segment six SD-OCT features achieved the mean accuracy of 0.930 (95% CI: 0.916–0.943), dice coefficients of 0.873 (95% CI: 0.847–0.899), a sensitivity of 0.873 (95% CI: 0.844–0.910), and a specificity of 0.922 (95% CI: 0.905–0.940). The six-metric model including EZ and ELM achieved the optimal performance to predict 1-year disease activity, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.980, the accuracy of 0.930, the sensitivity of 0.920, and the specificity of 0.962. The integrity of EZ and ELM significantly improved the performance of the six-metric model than that of the four-metric model.

Conclusion

The prediction model reveals the potential to predict PDA in nAMD eyes. The integrity of EZ and ELM constituted the strongest predictive factor for PDA in nAMD eyes in real-world clinical practice. The results of this study are a significant step toward image-guided prediction of long-term disease activity in the management of nAMD and highlight the importance of the automatic identification of photoreceptor layers.