Risk factors for age-related macular degeneration: Pooled findings from three continents

Understanding AMD by analogy: systematic review of lipid-related common pathogenic mechanisms in AMD, AD, AS and GN

RATIONALE

Age-related macular degeneration (AMD) is one of the leading causes of blindness among the elderly. Due to its complex etiology, current treatments have been insufficient. Previous studies reveal three systems closely involved in AMD pathogenesis: lipid metabolism, oxidation and inflammation. These systems are also involved in Alzheimer's disease, atherosclerosis and glomerulonephritis. Understanding commonalities of these four diseases may provide insight into AMD etiology.

OBJECTIVES

To understand AMD pathogenesis by analogy and suggest ideas for future research, this study summarizes main commonalities in disease pathogenesis of AMD, Alzheimer's disease, atherosclerosis and glomerulonephritis.

METHODS

Articles were identified through PubMed, Ovid Medline and Google Scholar. We summarized the common findings and synthesized critical differences.

RESULTS

Oxidation, lipid deposition, complement activation, and macrophage recruitment are involved in all four diseases shown by genetic, molecular, animal and human studies. Shared genetic variations further strengthen their connection. Potential areas for future research are suggested throughout the review.

CONCLUSIONS

The four diseases share many steps of an overall framework of pathogenesis. Various oxidative sources cause oxidative stress. Oxidized lipids and related molecules accumulate and lead to complement activation, macrophage recruitment and pathology. Investigations that arise under this structure may aid us to better understand AMD pathology.

Review of the association between retinal microvascular characteristics and eye disease

Computerized retinal imaging technologies enable the static and dynamic measurement of a range of retinal microvascular parameters. Large population-based studies have reported associations between these microvascular indices and various ophthalmic diseases including diabetes, age-related macular degeneration, retinal artery embolism, retinal vein occlusion, glaucoma and non-glaucomatous optic neuropathies. Increasingly, sophisticated imaging and analysis techniques have the potential to provide relevant clinical information regarding disease risk and progression; however, further studies are required to verify associations and strengthen the predictive power of these techniques. We summarize the current state of knowledge regarding retinal microvascular characteristics and eye disease.

Serum starvation of ARPE-19 changes the cellular distribution of cholesterol and Fibulin3 in patterns reminiscent of age-related macular degeneration

Retinal pigment epithelium (RPE) has been implicated as key source of cholesterol-rich deposits at Bruch's membrane (BrM) and in drusen in aging human eye. We have shown that serum-deprivation of confluent RPE cells is associated with upregulation of cholesterol synthesis and accumulation of unesterified cholesterol (UC). Here we investigate the cellular processes involved in this response. We compared the distribution and localization of UC and esterified cholesterol (EC); the age-related macular degeneration (AMD) associated EFEMP1/Fibulin3 (Fib3); and levels of acyl-coenzyme A (CoA): cholesterol acyltransferases (ACAT) ACAT1, ACAT2 and Apolipoprotein B (ApoB) in ARPE-19 cells cultured in serum-supplemented and serum-free media. The results were compared with distributions of these lipids and proteins in human donor eyes with AMD. Serum deprivation of ARPE-19 was associated with increased formation of FM dye-positive membrane vesicles, many of which co-labeled for UC. Additionally, UC colocalized with Fib3 in distinct granules. By day 5, serum-deprived cells grown on transwells secreted Fib3 basally into the matrix. While mRNA and protein levels of ACTA1 were constant over several days of serum-deprivation, ACAT2 levels increased significantly after serum-deprivation, suggesting increased formation of EC. The lower levels of intracellular EC observed under serum-deprivation were associated with increased formation and secretion of ApoB. The responses to serum-deprivation in RPE-derived cells: accumulation and secretion of lipids, lipoproteins, and Fib3 are very similar to patterns seen in human donor eyes with AMD and suggest that this model mimics processes relevant to disease progression.

Investigation of time to first presentation and extrahospital factors in the treatment of neovascular age-related macular degeneration: a retrospective cross-sectional study

OBJECTIVES

To assess the time from symptom onset to treatment for neovascular age-related macular degeneration (nvAMD) and to measure the awareness of AMD in Southeast Scotland.

DESIGN

Retrospective cross-sectional study.

SETTING

Secondary care, Southeast of Scotland.

METHODS

Patients treated with intravitreal therapy (IVT) for nvAMD in Southeast Scotland between 2013 and 2015 were identified using a treatment register. Notes were retrospectively reviewed. We measured time from: (A) symptom onset to first presentation at primary care, (B) referral to ophthalmic clinic appointment and (C) ophthalmic clinic appointment to first IVT treatment. To investigate AMD awareness, we performed a cluster random sample survey of patients visiting non-AMD ophthalmic clinics using a previously validated 12-item questionnaire.

RESULTS

195 patients (mean age 78 years) were included in the study. The mean delays between the different stages-A, B and C-were 54.2 (95% CI ±13), 28.2 (95% CI ±4.0) and 31.5 (95% CI ±3.6) days, respectively. There was an additional mean delay of 7.5 (95% CI ±1.6) days when patients were indirectly referred by optometrists via general practitioners (P<0.05). 140 patients (mean age 78) participated in the awareness survey; 62.1% reported being 'aware' of AMD but only 37.3% described AMD symptoms correctly.

CONCLUSIONS

There was a significant delay at every step of the nvAMD care pathway. The causes for this were multifactorial and included delays in first presentation to a healthcare provider, referral from primary care and initiation of secondary care treatment. Our data are likely to underestimate prehospital delays as a large number of cases are likely to have undefined symptoms and onset. We also identified suboptimal awareness of AMD which could account for a substantial delay in presentation from symptom onset. These findings highlight the need to address AMD awareness and the need for urgent treatment to prevent avoidable vision loss resulting from nvAMD.

Association of Rare Predicted Loss-of-Function Variants in Cellular Pathways with Sub-Phenotypes in Age-Related Macular Degeneration

PURPOSE

To investigate the association of rare predicted loss-of-function (pLoF) variants within age-related macular degeneration (AMD) risk loci and AMD sub-phenotypes.

DESIGN

Case-control study.

PARTICIPANTS

Participants of AREDS, AREDS2, and Michigan Genomics Initiative.

METHODS

Whole genome sequencing data were analyzed for rare pLoF variants (frequency <0.1%) in the regions of previously identified 52 independent risk variants known to be associated with AMD. Frequency of the rare pLoF variants in cases with intermediate or advanced AMD was compared with controls. Variants were assigned to the complement, extracellular matrix (ECM), lipid, cell survival, immune system, metabolism, or unknown/other pathway. Associations of rare pLoF variant pathways with AMD sub-phenotypes were analyzed using logistic and linear regression, and Cox proportional hazards models.

MAIN OUTCOME MEASURES

Differences in rare pLoF variant pathway burden and association of rare pLoF variant pathways with sub-phenotypes within the population with AMD were evaluated.

RESULTS

Rare pLoF variants were found in 298 of 1689 cases (17.6%) and 237 of 1518 controls (15.6%) (odds ratio [OR], 1.11; 95% confidence interval [CI], 0.91-1.36; P = 0.310). An enrichment of rare pLoF variants in the complement pathway in cases versus controls (OR, 2.94; 95% CI, 1.49-5.79; P = 0.002) was observed. Within cases, associations between all rare pLoF variants and choroidal neovascularization (CNV) (OR, 1.34; 95% CI, 1.04-1.73; P = 0.023), calcified drusen (OR, 1.33; 95% CI, 1.04-1.72; P = 0.025), higher scores on the AREDS Extended AMD Severity Scale (Standardized Coefficient Beta (β)=0.346 [0.086-0.605], P = 0.009), and progression to advanced disease (hazard ratio, 1.25; 95% CI, 1.01-1.55; P = 0.042) were observed. At the pathway level, there were associations between the complement pathway and geographic atrophy (GA) (OR, 2.17; 95% CI, 1.12-4.24; P = 0.023), the complement pathway and calcified drusen (OR, 3.75; 95% CI, 1.79-7.86; P < 0.001), and the ECM pathway and more severe levels in the AREDS Extended AMD Severity Scale (β = 0.62; 95% CI, 0.04-1.20; P = 0.035).

CONCLUSIONS

Rare pLoF variants are associated with disease progression. Variants in the complement pathway modify the clinical course of AMD and increase the risk of developing specific sub-phenotypes.

Associations between fruit and vegetable, and antioxidant nutrient intake and age-related macular degeneration by smoking status in elderly Korean men

Background

Age-related macular degeneration (AMD) is one of the major causes of irreversible blindness. The objective of this study was to determine whether there is any relationship between dietary intake of fruits and vegetables (F&V) and antioxidant nutrients including carotenoids and AMD according to smoking status in elderly men.

Methods

We performed a cross-sectional analysis using nationally representative samples of elderly aged ≥ 65 years (n = 1414) from the Korea National Health and Nutrition Examination Survey (KNHANES, 2010–2012).

Results

The current smokers consumed less food in total, and, in particular, less cereals/potatoes/sugar products, fruits and vegetables than the nonsmokers and former smokers (p < 0.05). Intake of energy, thiamin, vitamin C, vitamin A, and β-carotene were significantly lower in the current smokers than in the nonsmokers and the former smokers. For current smokers, the ORs of the highest tertile compared with the lowest tertile were 0.36 (95% CI: 0.14–0.96, p for trend = 0.0576) for F&V, 0.32 (95% CI: 0.12–0.85, p for trend = 0.0561) for vitamin C, 0.23 (95% CI: 0.08–0.67, p for trend = 0.0038) for α-carotene, 0.13 (95% CI: 0.04–0.46, p for trend = 0.0003) for β-carotene after adjusting for confounding factors. In contrast, there was no association between antioxidant nutrient intake and AMD among the nonsmokers and former smokers.

Conclusions

These results suggest that increased consumption of fruits and vegetables containing antioxidant components such as vitamin C, α-carotene, and β-carotene may have a protective effect on AMD. These effects may be more evident among current smokers.

Oxidative stress and reactive oxygen species: a review of their role in ocular disease

For many years, oxidative stress arising from the ubiquitous production of reactive oxygen species (ROS) has been implicated in the pathogenesis of various eye diseases. While emerging research has provided some evidence of the important physiological role of ROS in normal cell function, disease may arise where the concentration of ROS exceeds and overwhelms the body’s natural defence against them. Additionally, ROS may induce genomic aberrations which affect cellular homoeostasis and may result in disease. This literature review examines the current evidence for the role of oxidative stress in important ocular diseases with a view to identifying potential therapeutic targets for future study. The need is particularly pressing in developing treatments for conditions which remain notoriously difficult to treat, including glaucoma, diabetic retinopathy and age-related macular degeneration.

MicroRNA signatures in vitreous humour and plasma of patients with exudative AMD

Age-related macular degeneration (AMD) is a leading cause of blindness worldwide affecting individuals over the age of 50. The neovascular form (NV AMD) is characterized by choroidal neovascularization (CNV) and responsible for the majority of central vision impairment. Using non-biased microRNA arrays and individual TaqMan qPCRs, we profiled miRNAs in the vitreous humour and plasma of patients with NV AMD. We identified a disease-associated increase in miR-146a and a decrease in miR-106b and miR-152 in the vitreous humour which was reproducible in plasma. Moreover, miR-146a/miR-106b ratios discriminated patients with NV AMD with an area under the Receiver Operating Characteristic curve (ROC AUC) of 0,977 in vitreous humour and 0,915 in plasma suggesting potential for a blood-based diagnostic. Furthermore, using the AMD Gene Consortium (AGC) we mapped a NV AMD-associated SNP (rs1063320) in a binding site for miR-152-3p in the HLA-G gene. The relationship between our detected miRNAs and NV AMD related genes was also investigated using gene sets derived from the Ingenuity Pathway Analysis (IPA). To our knowledge, our study is the first to correlate vitreal and plasma miRNA signatures with NV AMD, highlighting potential future worth as biomarkers and providing insight on NV AMD pathogenesis.

Prevalence of Age-Related Macular Degeneration in Australia: The Australian National Eye Health Survey

Importance

Age-related macular degeneration (AMD) is a leading cause of irreversible blindness among the elderly population globally. Currently, knowledge of the epidemiology of AMD in Australia remains scarce because of a paucity of recent population-based data.

Objective

To examine the prevalence of AMD in Australia.

Design, Setting, and Participants

In this population-based, cross-sectional survey performed from March 11, 2015, to April 18, 2016, a sample of 3098 nonindigenous Australians 50 years and older and 1738 indigenous Australians 40 years and older from 30 geographic areas across Australia were examined.

Main Outcomes and Measures

Any AMD, early AMD, intermediate AMD, and late AMD graded according to the Beckman clinical classification system.

Results

A total of 4836 individuals were examined, including 3098 nonindigenous Australian (64.1%; 58.9% female vs 41.1% male; age range, 40-92 years; mean [SD] age, 55.0 [10.0] years) and 1738 indigenous Australians (35.9%; 53.6% female vs 46.4% male; age range, 50-98 years; mean [SD] age, 66.6 [9.7] years). A total of 4589 (94.9%, 2946 nonindigenous and 1643 indigenous) participants had retinal photographs in at least 1 eye that were gradable for AMD. The weighted prevalence of early AMD was 14.8% (95% CI, 11.7%-18.6%) and of intermediate AMD was 10.5% (95% CI, 8.3%-13.1%) among nonindigenous Australians. In indigenous Australians, the weighted prevalence of early AMD was 13.8% (95% CI, 9.7%-19.3%) and of intermediate AMD was 5.7% (96% CI, 4.7%-7.0%). Late AMD was found in 0.96% (95% CI, 0.59%-1.55%) of nonindigenous participants (atrophic, 0.72%; neovascular, 0.24%). The prevalence of late AMD increased to 6.7% in participants 80 years or older and was higher in men (1.4% vs 0.61%, P = .02). Only 3 (0.17% [95% CI, 0.04%-0.63%]) indigenous participants had late (atrophic) AMD. Age-related macular degeneration was attributed as the main cause of vision loss (<6/12 in the better eye) in 23 of 208 nonindigenous Australians (11.1%) and 2 of 183 indigenous Australians (1.1%).

Conclusions and Relevance

In line with data from other white populations, AMD is a prominent cause of vision loss in the nonindigenous Australian population. An increased provision of low vision rehabilitation services may be required to cope with the projected increase in AMD in Australia.

Updates on the Epidemiology of Age-Related Macular Degeneration

This meta-analysis reports on current estimates of the prevalence of age-related macular degeneration (AMD) based on a review of recent meta-analyses and literature research. Within an age of 45-85 years, global prevalences of any AMD, early AMD, and late AMD were 8.7% [95% credible interval (CrI), 4.3‒17.4], 8.0% (95% CrI, 4.0‒15.5), and 0.4% (95% CrI, 0.2-0.8). Early AMD was more common in individuals of European ancestry (11.2%) than in Asians (6.8%), whereas prevalence of late AMD did not differ significantly. AMD of any type was less common in individuals of African ancestry. The number of individuals with AMD was estimated to be 196 million (95% CrI, 140‒261) in 2020 and 288 million (95% CrI, 205‒399) in 2040. The worldwide number of persons blind (presenting visual acuity < 3/60) or with moderate to severe vision impairment (MSVI; presenting visual acuity < 6/18 to 3/60 inclusive) due to macular disease in 2010 was 2.1 million [95% uncertainty interval (UI), 1.9‒2.7] individuals out of 32.4 million individuals blind and 6.0 million (95% UI, 5.2‒8.1) persons out of 191 million people with MSVI. Age-standardized prevalence of macular diseases as cause of blindness in adults aged 50+ years worldwide decreased from 0.2% (95% UI, 0.2‒0.2) in 1990 to 0.1% (95% UI, 0.1‒0.2) in 2010; as cause for MSVI, it remained mostly unchanged (1990: 0.4%; 95% UI, 0.3‒0.5; 2010: 0.4%; 95% UI, 0.4‒0.6), with no significant sex difference. In 2015, AMD was the fourth most common cause of blindness globally (in approximately 5.8% of blind individuals) and third most common cause for MSVI (3.9%). These data show the globally increasing importance of AMD.

Neovascular age-related macular degeneration is not associated with coronary heart disease in a Chinese Population: a population-based study

PURPOSE

This case-control study aimed to explore the association between prior coronary heart disease (CHD) and neovascular age-related macular degeneration (AMD) using a population-based data set in Taiwan.

METHODS

We analysed data sourced from the Taiwan Longitudinal Health Insurance Database 2005. The study consisted of 1970 patients with neovascular AMD as cases and 5910 age- and sex-matched controls. We performed a conditional logistic regression to examine the odds ratio (OR) and its corresponding 95% confidence interval (CI) for previously diagnosed CHD between cases and controls.

RESULTS

Of the 7880 sampled patients, 24.5% had a prior history of CHD; CHD was found in 25.7% of cases and in 22.7% of controls (p = 0.008). The conditional logistic regression analysis indicated that the OR for prior CHD for cases was 1.17 [95% confidence interval (CI): 1.04-1.32] compared to the controls. However, after adjusting for patient's monthly income, geographic location, urbanization level, age, hyperlipidaemia, diabetes and hypertension, we failed to observe an association between prior CHD and AMD (OR = 1.03, 95% CI = 0.91-1.17). Additionally, the medical comorbidities of hyperlipidaemia (adjusted OR = 1.29, 95% CI = 1.15-1.45), hypertension (adjusted OR = 1.20, 95% CI = 1.05-1.37) and diabetes (adjusted OR = 1.47, 95% CI = 1.32-1.65) were significantly associated with AMD.

CONCLUSIONS

This study presented no significant difference in the odds of prior CHD between patients with AMD and those without AMD after adjusting for comorbidities and sociodemographic characteristics in a Chinese population.

Spatiotemporal characteristics of retinal response to network-mediated photovoltaic stimulation

Subretinal prostheses aim at restoring sight to patients blinded by photoreceptor degeneration using electrical activation of the surviving inner retinal neurons. Today, such implants deliver visual information with low-frequency stimulation, resulting in discontinuous visual percepts. We measured retinal responses to complex visual stimuli delivered at video rate via a photovoltaic subretinal implant and by visible light. Using a multielectrode array to record from retinal ganglion cells (RGCs) in the healthy and degenerated rat retina ex vivo, we estimated their spatiotemporal properties from the spike-triggered average responses to photovoltaic binary white noise stimulus with 70-μm pixel size at 20-Hz frame rate. The average photovoltaic receptive field size was 194 ± 3 μm (mean ± SE), similar to that of visual responses (221 ± 4 μm), but response latency was significantly shorter with photovoltaic stimulation. Both visual and photovoltaic receptive fields had an opposing center-surround structure. In the healthy retina, ON RGCs had photovoltaic OFF responses, and vice versa. This reversal is consistent with depolarization of photoreceptors by electrical pulses, as opposed to their hyperpolarization under increasing light, although alternative mechanisms cannot be excluded. In degenerate retina, both ON and OFF photovoltaic responses were observed, but in the absence of visual responses, it is not clear what functional RGC types they correspond to. Degenerate retina maintained the antagonistic center-surround organization of receptive fields. These fast and spatially localized network-mediated ON and OFF responses to subretinal stimulation via photovoltaic pixels with local return electrodes raise confidence in the possibility of providing more functional prosthetic vision. NEW & NOTEWORTHY Retinal prostheses currently in clinical use have struggled to deliver visual information at naturalistic frequencies, resulting in discontinuous percepts. We demonstrate modulation of the retinal ganglion cells (RGC) activity using complex spatiotemporal stimuli delivered via subretinal photovoltaic implant at 20 Hz in healthy and in degenerate retina. RGCs exhibit fast and localized ON and OFF network-mediated responses, with antagonistic center-surround organization of their receptive fields.

ApoA-I Mimetic Peptide 4F Reduces Age-Related Lipid Deposition in Murine Bruch's Membrane and Causes Its Structural Remodeling

PURPOSE

Accumulation of lipoprotein-derived lipids including esterified and unesterified cholesterol in Bruch's membrane of human eyes is a major age-related change involved in initiating and sustaining soft drusen in age-related macular degeneration (AMD). The apolipoprotein (apo) A-I mimetic peptide 4F is a small anti-inflammatory and anti-atherogenic agent, and potent modifier of plasma membranes. We evaluated the effect of intravitreally-injected 4F on murine Bruch's membrane.

METHODS

We tested single intravitreal injections of 4F doses (0.6 µg, 1.2 µg, 2.4 µg, and placebo scrambled peptide) in ApoE^null mice ≥10 months of age. After 30 days, mice were euthanized. Eyes were processed for either direct immunofluorescence detection of esterified cholesterol (EC) in Bruch's membrane whole mounts via a perfringolysin O-based marker linked to green fluorescent protein or by transmission electron microscopic visualization of Bruch's membrane integrity. Fluorescein isothiocyanate-conjugated 4F was traced after injection.

RESULTS

All injected eyes showed a dose-dependent reduction of Bruch's membrane EC with a concomitant ultrastructural improvement compared to placebo treated eyes. At a 2.4 µg dose of 4F, EC was reduced on average by ~60% and Bruch's membrane returned to a regular pentalaminar structure and thickness. Tracer studies confirmed that injected 4F reached intraocular targets.

CONCLUSION

We demonstrated a highly effective pharmacological reduction of EC and restoration of Bruch's membrane ultrastructure. The apoA-I mimetic peptide 4F is a novel way to treat a critical AMD disease process and thus represents a new candidate for treating the underlying cause of AMD.

Functional changes at the preferred retinal locus in subjects with bilateral central vision loss

PURPOSE

Subjects with bilateral central vision loss (CVL) use a retinal region called the preferred retinal locus (PRL) for performing various visual tasks. We probed the fixation PRL in individuals with bilateral macular disease, including age-related macular degeneration (AMD) and Stargardt disease (STGD), for localized sensitivity deficits.

METHODS

Three letter words at the critical print size were presented in the NIDEK MP-1 microperimeter to determine the fixation PRL and its radial retinal eccentricity from the residual fovea in 29 subjects with bilateral CVL. Fixation stability was defined as the median bivariate contour ellipse area (BCEA) from 3 fixation assessments. A standard 10-2 grid (68 locations, 2° apart) was used to determine central retinal sensitivity for Goldmann size II test spots. Baseline and follow-up supra-threshold screening of the fixation PRL for localized sensitivity deficits was performed using high density (0.2° or 0.3° apart) 0 dB Goldmann size II test spots. Custom MATLAB code and a dual bootstrapping algorithm were used to register test-spot locations from the baseline and follow-up tests. Locations where the 0 dB test spots were not seen on either test were labeled as micro-scotomas (MSs).

RESULTS

Median BCEA correlated poorly with the radial eccentricity of the fixation PRL. Mean (±SD) sensitivity around the PRL from 10-2 testing was 4.93 ± 4.73 dB. The average percentage of MSs was similar for patients with AMD (25.4%), STGD (20.3%), and other etiologies of CVL (27.1%).

CONCLUSIONS

The fixation PRL in subjects with bilateral CVL frequently includes local regions of sensitivity loss.

VEGF Polymorphisms Among Neovascular Age-Related Macular Degenerative Subjects in a Multiethnic Population

AIM

To determine the association of vascular endothelial growth factor (VEGF) polymorphisms with neovascular age-related macular degeneration (nAMD).

MATERIALS AND METHODS

One hundred thirty-five nAMD patients and 135 controls were recruited to determine the association of the -460 C/T, the -2549 I/D, and the +405 G/C polymorphisms with the VEGF gene. Genotyping was conducted using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach, and association analyses were conducted using chi-square analysis and logistic regression analysis.

RESULTS

A significant association was observed between nAMD and the VEGF +405 G/C genotypes (p = 0.002) and alleles (odds ratio = 1.36, 95% confidence interval = 1.12-1.62, p = < 0.001) compared with the controls. This association was confirmed by logistic regression analyses, using two different genetic models (additive and dominant) resulting in p-values of p = 0.001 and p < 0.001, respectively. In addition, the dominant model of VEGF +405 G/C was also found to be at risk of the CC genotype with nAMD among subjects that were aged ≥60 years, female, of Chinese ethnicity, hypertensive, diabetic, and smokers.

CONCLUSION

With the exception of several limitations, the present study showed evidence of an association between the VEGF +405 G/C polymorphism and nAMD in Malaysian subjects.

[Epidemiology of age-related macular degeneration]

Age-related macular degeneration (AMD) is the main cause of blindness in industrialized societies. Population-based epidemiological investigations generate important data on prevalence, incidence, risk factors, and future trends. This review summarizes the most important epidemiological studies on AMD with a focus on their transferability to Germany including existing evidence for the main risk factors for AMD development and progression. Future tasks, such as the standardization of grading systems and the use of recent retinal imaging technology in epidemiological studies are discussed. In Germany, epidemiological data on AMD are scarce. However, the need for epidemiological research in ophthalmology is currently being addressed by several recently started population-based studies.

Recent developments in age-related macular degeneration: a review

Background

Visual impairment in elderly people is a considerable health problem that significantly affects quality of life of millions worldwide. The magnitude of this issue is becoming more evident with an aging population and an increasing number of older individuals.

Objective

The objective of this article was to review the clinical and pathological aspects of age-related macular degeneration (AMD), diagnostic tools, and therapeutic modalities presently available or underway for both atrophic and wet forms of the disease.

Methods

An online review of the PubMed database was performed, searching for the key words. The search was limited to articles published since 1980 to date.

Results

Several risk factors have been linked to AMD, such as age (>60 years), lifestyle (smoking and diet), and family history. Although the pathogenesis of AMD remains unclear, genetic factors have been implicated in the condition. Treatment for atrophic AMD is mainly close observation, coupled with nutritional supplements such as zinc and antioxidants, whereas treatment of wet AMD is based on targeting choroidal neovascular membranes.

Conclusion

Identification of modifiable risk factors would improve the possibilities of preventing the progression of AMD. The role of anti-vascular endothelial growth factor (anti-VEGF) agents has transformed the therapeutic approach of the potentially blinding disease “wet AMD” into a more favorable outcome.

Evaluation of coronary artery disease as a risk factor for reticular pseudodrusen

PURPOSE

Reticular pseudodrusen (RPD) are a risk factor for late age-related macular degeneration (AMD). Associations between RPD and coronary artery disease (CAD) have been reported from small case-control studies. This study investigated the association of RPD within a predominantly CAD cohort.

METHODS

A subgroup of subjects from a multicentre randomised controlled trial of CT coronary angiography (CTCA) underwent ultrawide field (UWF) retinal imaging CAD determined by CTCA and was categorised as normal, non-obstructive or obstructive. Specific AMD features in UWF images were graded. Standardised grids were used to record the spatial location of AMD features, including RPD. Multivariate confounder adjusted regression models assessed the association between RPD and CAD.

RESULTS

The 534 participants were aged 27-75 years (mean 58±9 years; 425 (80%) ≥50 years) with a male preponderance (56%). Within the study sample, 178 (33%) had no CAD, 351 (66%) had CAD. RPD was detected in 30 participants (5.6%) and bilaterally in 23. Most participants with bilateral RPD had intermediate AMD 17 (74%). After adjustment for potential confounders (age, sex, drusen >125 µm, smoking status), multivariate analysis found no significant association between CAD and RPD (OR 1.31; 95% CI (0.57 to 3.01); p=0.52). A significant association was identified between RPD and intermediate AMD (OR 3.18; 95% CI (1.61 to 6.27); p=0.001).

CONCLUSION

We found no evidence to support an association between CAD and RPD. RPD was strongly associated with intermediate AMD features.

TRIAL REGISTRATION NUMBER

NCT01149590, Post results.

An inducible form of Nrf2 confers enhanced protection against acute oxidative stresses in RPE cells

Increasing evidence suggests that overt oxidative stress within the retina plays an important role in the progression of age-related retinal decline, and in particular, in the disease age-related macular degeneration (AMD). Nuclear factor erythroid 2-like 2 (Nrf2) is a master transcription factor that upregulates numerous of antioxidant/detoxification genes. Nrf2^-/- mice develop progressive retinal degeneration that includes the formation of drusen-like deposits, lipofuscin, and sub-retinal pigment epithelium (RPE) deposition of inflammatory proteins. Furthermore, strategies that promote Nrf2 activation have shown promise for the treatment of cone/rod dystrophies and other forms of retinal degeneration. Herein we explored whether utilizing a small molecule-inducible version of Nrf2 confers additional protection against oxidative stresses when compared to a constitutively expressed version of Nrf2. Stable populations of human ARPE-19 cells were generated that express either constitutive FLAG-tagged (FT) Nrf2 (FT cNrf2) or doxycycline (dox)-inducible FT Nrf2 (FT iNrf2) at low levels (∼4.5 fold vs. endogenous). Expression of either FT cNRF2 or FT iNrf2 upregulated canonical antioxidant genes (e.g., NQO1, GCLC). Both FT cNrf2 and FT iNrf2 ARPE-19 cells were protected from cigarette smoke extract-induced nitric oxide generation to similar extents. However, only FT iNrf2 cells demonstrated enhanced resistance to doxorubicin and cumene hydroperoxide-mediated increases in mitochondrial superoxide and lipid peroxidation, respectively, and did so in a dox-dependent manner. These results suggest that therapeutic approaches which conditionally control Nrf2 activity may provide additional protection against acute oxidative stresses when compared to constitutively expressed Nrf2 strategies.

Physical Activity and Age-related Macular Degeneration: A Systematic Literature Review and Meta-analysis

PURPOSE

To better understand the association, in a white population, of physical activity and age-related macular degeneration (AMD)-the main cause of irreversible severe vision loss in developed countries-given the suggestion that a healthy lifestyle may assist in delaying the onset and progression of AMD.

DESIGN

Systematic review and meta-analysis.

METHODS

Medline, EMBASE, and Google Scholar were systematically searched for studies up to May 2015. Reference lists of published articles were hand searched and study authors were contacted to provide additional data. Those in the lowest category of activity in each study were compared with all other participants to assess the association between physical activity and both early and late AMD using random-effects meta-analysis.

RESULTS

Nine studies (subject age range 30-97 years) were included in the meta-analysis. Physical activity was found to have a protective association with both early AMD (8 studies, n = 38 112, odds ratio (OR) 0.92, 95% confidence interval [CI] 0.86-0.98) and late AMD (7 studies, n = 28 854, OR 0.59, 95% CI 0.49-0.72).

CONCLUSIONS

Physical activity is associated with lower odds of early and late AMD in white populations. These findings have important implications, reinforcing the public health message of staying active throughout life. However, further longitudinal studies are required to confirm and further characterize a protective effect of physical activity on the onset and/or progression of AMD.

Combined influence of poor health behaviours on the prevalence and 15-year incidence of age-related macular degeneration

We aimed to establish the collective influence of four lifestyle practices (physical activity, diet, smoking and alcohol consumption) on the prevalence and incidence of AMD. At baseline, 2428 participants aged 49+ with complete lifestyle and AMD data were examined, and of these, 1903 participants were re-examined 15 years later. AMD was assessed from retinal photographs. A health behaviour score was calculated, allocating 1 point for each poor behaviour: current smoking; fruits and vegetables consumed <4 serves daily; <3 episodes of physical activity per week; and >2 alcoholic drinks per day. Cross-sectional analysis showed that participants who engaged in all 4 poor health behaviours (n = 29) versus those who did not engage in unhealthy behaviours (reference group; n = 677) had greater odds of any and late AMD: multivariable-adjusted OR, 5.14 (95% CI, 1.04–25.45) and OR 29.53 (95% CI 2.72–321.16), respectively. A marginally non-significant association was observed between increasing number of poor health behaviours and 15-year incidence of early AMD (multivariable-adjusted P-trend = 0.08). Our data suggests that motivating patients with AMD to eat better, exercise more, limit alcohol intake and avoid smoking seems advisable to decelerate the development or worsening of existing AMD.

Deletion of Efemp1 Is Protective Against the Development of Sub-RPE Deposits in Mouse Eyes

Purpose

EFEMP1 (fibulin-3) is mutated in Malattia Leventinese/Doyne's honeycomb retinal dystrophy (ML/DHRD), an inherited macular dystrophy similar to AMD. Both ML/DHRD and AMD are characterized by the presence of sub-RPE deposits. Efemp1 knockout mice do not develop sub-RPE deposits. This study was to test whether sub-RPE deposits can be induced in Efemp1 knockout mice by experimentally applied stress conditions that cause wild-type mice to develop sub-RPE deposits.

Methods

Efemp1 knockout and control mice at 6, 18, or 24 months old were fed with a synthetic high-fat diet (HFD). Beginning 1 month after starting the HFD, one group of mice was exposed to cigarette smoke daily for 1 month, and another group of mice was subjected to photochemical injury every other day for 2 weeks from a 488-nm argon laser. After the treatments, histologic analysis was performed to assess whether sub-RPE deposits were induced.

Results

Basal laminar deposits (BLamDs), a form of sub-RPE deposits, were observed in the 18- and 24-month-old wild-type mice but not in Efemp1 knockout mice in any age groups after exposure to HFD and cigarette smoke or laser injury.

Conclusions

Mice lacking fibulin-3 do not develop sub-RPE deposits. Environmental oxidative stressors (HFD/cigarette smoke or HFD/laser) known to cause BLamD formation in wild-type mice failed to induce BLamD formation in Efemp1 knockout mice. These results suggest that fibulin-3 is a central player in the development of BLamD, and deletion of fibulin-3 is protective against the development of BLamD.

Natural History of Rod-Mediated Dark Adaptation over 2 Years in Intermediate Age-Related Macular Degeneration

Purpose

To characterize the natural history of rod-mediated dark adaptation (RMDA) over 2 years in eyes with intermediate age-related macular degeneration (AMD). This information will be useful in understanding the potential of RMDA to serve as a functional endpoint in proof-of-concept studies and clinical trials on intermediate AMD.

Methods

RMDA was measured in eyes with intermediate AMD at baseline and follow-up visits over 2 years at 6, 12, 18, and 24 months. A computerized dark adaptometer measured sensitivity for targets centered at 11° on the superior vertical meridian of the retina. Rod intercept time (RIT) characterized the speed of dark adaptation and was defined as the duration (in minutes) required for sensitivity to reach a criterion level of 3.0 log units of attenuation of the stimulus.

Results

Mean change in RIT over 24 months for 30 eyes was 10.5 minutes (standard deviation 19.4), p < 0.0001; 73.3% of eyes had a RIT increase >1 minute, 56.7% had an increase >3 minutes, and 36.7% had an increase >6 minutes; for 26.7% RIT was unchanged (0- to 1-minute increase) or decreased. Greater increase in RIT over 24 months was associated with smoking.

Conclusions

RMDA slows in intermediate AMD over 2 years in most eyes. There was wide variability in RIT at both baseline and in the extent to which it increased over 24 months. A major risk factor for AMD, smoking, exacerbated RMDA slowing.

Translational Relevance

RMDA as assessed by RIT may be useful as a functional endpoint in proof-of-concept studies and clinical trials on intermediate AMD with 2-year designs.

Homocysteine & its metabolite homocysteine-thiolactone & deficiency of copper in patients with age related macular degeneration - A pilot study

Background & objectives:

Age related macular degeneration (ARMD) is a leading cause of blindness, particularly in persons above 60 yr of age. Homocysteine is implicated in many ocular diseases including ARMD. This study was undertaken to assess the status and relationship between plasma homocysteine, homocysteine - thiolactone, homocysteinylated protein and copper levels in patients with ARMD.

Methods:

A total of 16 patients with ARMD and 16 age-matched controls were recruited for the study. Plasma glutathione, homocysteine, homocysteine - thiolactone and extent of homocysteine conjugation with proteins, copper and thiobarbituric acid reactive substances were measured.

Results:

Homocysteine levels were elevated with increase in homocysteine-thiolactone, thiobarbituric acid reactive substances and a decrease of glutathione. The levels of homocysteinylated protein were elevated in ARMD. The elevated homocysteine, homocysteine-thiolactone correlated with the decrease in copper level.

Interpretation & conclusions:

Elevated homocysteine and its metabolite homocysteine-thiolactone and decreased levels of copper may play an important role in the pathogenesis of ARMD.

Full-thickness macular hole formation following anti-VEGF injections for neovascular age-related macular degeneration

PURPOSE

Macular hole (MH) is part of a group of age-related degenerative diseases characterized by pathology of vitreomacular interface. Similarly, neovascular age-related macular degeneration (nAMD) affects older patients and is a leading cause of irreversible visual loss. The purpose of this case series is to describe the development of full-thickness MH in patients with nAMD, following antivascular endothelial growth factor (anti-VEGF) treatment.

METHODS

Participants in this case series were four patients with nAMD, who received anti-VEGF injections with variable therapeutic response to treatment. Patients were examined at baseline (when AMD was diagnosed) and monthly thereafter. The examination included visual acuity measurement, slit-lamp biomicroscopy, and optical coherence tomography.

RESULTS

All patients were found to develop full-thickness MH within 1-4 months after the last anti-VEGF injection, even in the absence of pre-existing vitreomacular interface abnormalities in some cases. The median number of injections before the MH formation was 3.

CONCLUSION

MH formation may represent an adverse effect of anti-VEGF treatment in patients with nAMD and could be also coexisting pathology with nAMD in older individuals.

Aflibercept in age-related macular degeneration: evaluating its role as a primary therapeutic option

The recent VIEW studies have demonstrated the non-inferiority of monthly and bi-monthly aflibercept in the management of wet age related macular degeneration (AMD) compared with ranibizumab. However, the current data are limited mainly to fixed dosing regimens with few studies looking at flexible dosing regimens of aflibercept in wet AMD. In addition, recent data from the VIEW 96 week extension has shown that patients being shifted from fixed dosing regimens to PRN have shown a drop in visual acuity and increase in central macular thickness. This is an indication that fixed dosing, a non-sustainable option, is only effective as long as it is continued. Regimens such as treat and extend (TAE) and pro-re nata (PRN) have been studied extensively in ranibizumab and bevacizumab and have shown to be effective options. With the presence of effective, established and less costly drugs such as ranibizumab and bevacizumab, the role of aflibercept as a primary treatment modality has yet to be clearly defined. The current review provides an analysis of the VIEW studies, as well as the extension phases. It also looks at post hoc analysis of predictors of response and outcomes. We have also conducted a search on studies comparing between PRN regimens using aflibercept and other anti-VEGF agents. This review also explores cheaper off label aflibercept; ziv-aflibercept in the treatment of wet AMD. The main purpose of the review is to delineate the role of aflibercept as a primary therapeutic option and if there are any significant advantages that would advocate its use over alternative anti-VEGF drugs. Finally, we propose a treatment algorithm for patients being started on aflibercept during the first year and thereafter.

Extracellular matrix nitration alters growth factor release and activates bioactive complement in human retinal pigment epithelial cells

Purpose

We have shown previously that non-enzymatic nitration (NEN) of the extracellular matrix (ECM), which serves as a model of Bruch’s membrane (BM) aging, has a profound effect on the behavior of the overlying retinal pigment epithelial (RPE) cells, including altered phagocytic ability, reduced cell adhesion, and inhibition of proliferation. We know that transplanted RPE monolayers will encounter a hostile sub-RPE environment, including age-related alterations in BM that may compromise cell function and survival. Here we use our previous NEN model of BM aging to determine the effects of NEN of the ECM on growth factor release and complement activation in RPE cells.

Methods

Human induced-pluripotent stem cells (iPSCs) were differentiated into RPE cells, and confirmed by immunohistochemistry, confocal microscopy, and polymerase chain reaction. IPSC-derived RPE cells were plated onto RPE-derived ECM under untreated or nitrite-modified conditions. Cells were cultured for 7 days and barrier function measured by transepithelial resistance (TER). Vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF), and complement component C3a were measured using enzyme-linked immunosorbent assay (ELISA).

Results

On average nitrite-modified ECM increased VEGF release both apically and basally by 0.15 ± 0.014 ng/mL (p <0.0001) and 0.21 ± 0.022 ng/mL (p <0.0001), respectively, in iPSC-derived RPE cells. Nitrite-modified ECM increased PEDF release in iPSC-derived RPE cells apically by 0.16 ± 0.031 ng/mL (p <0.0001), but not basally (0.27 ± 0.015 vs. 0.32 ± 0.029 ng/mL, (p >0.05)). Nitrite-modified ECM increased production of C3a in iPSC-derived RPE cells by 0.52 ± 0.123 ng/mL (p <0.05).

Conclusion

Nitrite-modified ECM increased VEGF, PEDF release, and C3a production in human iPSC-derived RPE cells. This model demonstrates changes seen in the basement membrane can lead to alterations in the cell biology of the RPE cells that may be related to the development of age-related macular degeneration.

Pluripotent stem cells and their utility in treating photoreceptor degenerations

Age-related macular degeneration and inherited retinal degenerations represent the leading causes of blindness in industrialized countries. Despite different initiating causes, they share a common final pathophysiology, the loss of the light sensitive photoreceptors. Replacement by transplantation may offer a potential treatment strategy for both patient populations. The last decade has seen remarkable progress in our ability to generate retinal cell types, including photoreceptors, from a variety of murine and human pluripotent stem cell sources. Driven in large part by the requirement for renewable cell sources, stem cells have emerged not only as a promising source of replacement photoreceptors but also to provide in vitro systems with which to study retinal development and disease processes and to test therapeutic agents.

Effect of topical isopropyl unoprostone on macular atrophy progression in eyes with exudative age-related macular degeneration

BACKGROUND

To evaluate the efficacy and safety of topical isopropyl unoprostone (IU) in treating macular atrophy in age-related macular degeneration (AMD) patients.

METHODS

Fifty-two AMD patients with macular atrophy were included and randomly assigned (1:1) to the treatment (topical 0.15% IU) or placebo group. Subjects used study eye drops 3 times a day for 54 weeks. The macular atrophy was documented on fundus autofluorescence photographs and measured using RegionFinder. The enlargement rate of macular atrophy and the changes in visual acuity were examined statistically between baseline and 54 weeks.

RESULTS

Forty-eight subjects were included in the analyses because 4 subjects withdrew from the study. The differences between the IU and placebo groups in mean and median area of macular atrophy were not statistically significant at baseline. The baseline median lesion size of macular atrophy was 2.33 mm in the IU group and 1.63 mm in the placebo group (P = 0.51). The intergroup difference in the enlargement ratio of macular atrophy (21 ± 15% in the IU group and 111 ± 96% in the placebo group) was statistically significant (P < 0.001). Additionally, visual acuity tended to improve over baseline in the IU group. No serious adverse events were observed.

CONCLUSIONS

Topical IU therapy is safe and effective for treating macular atrophy in AMD patients.

Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances

PURPOSES

To evaluate the optical performance of blue-light filtering spectacle lenses and investigate whether a reduction in blue light transmission affects visual performance and sleep quality.

METHODS

Experiment 1: The relative changes in phototoxicity, scotopic sensitivity, and melatonin suppression of five blue-light filtering plano spectacle lenses were calculated based on their spectral transmittances measured by a spectrophotometer. Experiment 2: A pseudo-randomized controlled study was conducted to evaluate the clinical performance of two blue-light filtering spectacle lenses (BF: blue-filtering anti-reflection coating; BT: brown-tinted) with a regular clear lens (AR) serving as a control. A total of eighty computer users were recruited from two age cohorts (young adults: 18-30 yrs, middle-aged adults: 40-55 yrs). Contrast sensitivity under standard and glare conditions, and colour discrimination were measured using standard clinical tests. After one month of lens wear, subjective ratings of lens performance were collected by questionnaire.

RESULTS

All tested blue-light filtering spectacle lenses theoretically reduced the calculated phototoxicity by 10.6% to 23.6%. Although use of the blue-light filters also decreased scotopic sensitivity by 2.4% to 9.6%, and melatonin suppression by 5.8% to 15.0%, over 70% of the participants could not detect these optical changes. Our clinical tests revealed no significant decrease in contrast sensitivity either with (95% confidence intervals [CI]: AR-BT [-0.05, 0.05]; AR-BF [-0.05, 0.06]; BT-BF [-0.06, 0.06]) or without glare (95% CI: AR-BT [-0.01, 0.03]; AR-BF [-0.01, 0.03]; BT-BF [-0.02, 0.02]) and colour discrimination (95% CI: AR-BT [-9.07, 1.02]; AR-BF [-7.06, 4.46]; BT-BF [-3.12, 8.57]).

CONCLUSION

Blue-light filtering spectacle lenses can partially filter high-energy short-wavelength light without substantially degrading visual performance and sleep quality. These lenses may serve as a supplementary option for protecting the retina from potential blue-light hazard.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02821403.

The Age-Related Eye Disease 2 Study: Micronutrients in the Treatment of Macular Degeneration

Age-related macular degeneration (AMD) is one of the leading causes of vision loss in the elderly. With an increasingly aged population worldwide, the need for the prevention of AMD is rising. Multiple studies investigating AMD with the use of animal models and cell culture have identified oxidative stress-related retinal damage as an important contributing factor. In general, diet is an excellent source of the antioxidants, vitamins, and minerals necessary for healthy living; moreover, the general public is often receptive to recommendations made by physicians and health care workers regarding diet and supplements as a means of empowering themselves to avoid common and worrisome ailments such as AMD, which has made epidemiologists and clinicians enthusiastic about dietary intervention studies. A wide variety of nutrients, such as minerals, vitamins, ω-3 (n-3) fatty acids, and various carotenoids, have been associated with reducing the risk of AMD. Initial results from the Age-Related Eye Disease Study (AREDS) indicated that supplementation with antioxidants (β-carotene and vitamins C and E) and zinc was associated with a reduced risk of AMD progression. The AREDS2 follow-up study, designed to improve upon the earlier formulation, tested the addition of lutein, zeaxanthin, and ω-3 fatty acids. In this review, we examine the science behind the nutritional factors included in these interventional studies and the reasons for considering their inclusion to lower the rate of AMD progression.

Epidemiology of age-related macular degeneration (AMD): associations with cardiovascular disease phenotypes and lipid factors

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in adults over 50 years old. Genetic, epidemiological, and molecular studies are beginning to unravel the intricate mechanisms underlying this complex disease, which implicate the lipid-cholesterol pathway in the pathophysiology of disease development and progression. Many of the genetic and environmental risk factors associated with AMD are also associated with other complex degenerative diseases of advanced age, including cardiovascular disease (CVD). In this review, we present epidemiological findings associating AMD with a variety of lipid pathway genes, cardiovascular phenotypes, and relevant environmental exposures. Despite a number of studies showing significant associations between AMD and these lipid/cardiovascular factors, results have been mixed and as such the relationships among these factors and AMD remain controversial. It is imperative that researchers not only tease out the various contributions of such factors to AMD development but also the connections between AMD and CVD to develop optimal precision medical care for aging adults.

Financial burden and quality of life of informal caregivers of patients with wet age-related macular degeneration

PURPOSE

The purpose of this research is to quantify the cost burden, care times and the impact on the quality of life (QoL) of informal caring relatives caring for patients with wet age-related macular degeneration (wet AMD). Moreover we investigated the impact of care times on the QoL.

METHODS

Through a specifically designed questionnaire, 150 caring relatives were interviewed retrospectively on all accrued financial costs, caring times incurred and the current QoL, assessed by a Visual Analogue Scale for happiness (VAS).

RESULTS

The caring time incurred was on average 6.4 ± 8.5 (mean +/- SD) hours per week. The QoL was on average rated at 6.7 ± 1.9 on a ten point scale. Financial strain was incurred by the direct non-medical costs of on average € 405 ± 1104 and the direct medical costs of on average € 134 ± 340 per year. Indirect costs were stated by two caregivers as amounting to € 2400 and € 6000 net income loss per year respectively. Caregivers of privately insured patients with wet AMD carried a financial cost burden which was up to six times higher than caregivers of patients who were on state insurance while showing the same visual acuity.

CONCLUSION

The evaluation shows that caregivers of privately insured patients with wet AMD have higher costs than caregivers of patients with state insurance coverage. This burden seems to be a factor to be considered independently since it does not appear to have any relation to patients AMD acuity.

Features of Age-Related Macular Degeneration in the General Adults and Their Dependency on Age, Sex, and Smoking: Results from the German KORA Study

Age-related macular degeneration (AMD) is a vision impairing disease of the central retina characterized by early and late forms in individuals older than 50 years of age. However, there is little knowledge to what extent also younger adults are affected. We have thus set out to estimate the prevalence of early AMD features and late AMD in a general adult population by acquiring color fundus images in 2,840 individuals aged 25 to 74 years of the Cooperative Health Research in the Region of Augsburg project (KORA) in South Germany. Among the 2,546 participants with gradable images for each eye, 10.9% (n = 277) had early AMD features (applying the 9-step Age-Related Eye Disease Study Severity Scale), 0.2% (n = 6) had late AMD. Prevalence increased with age, reaching 26.3% for early AMD features and 1.9% for late AMD at the age 70+. However, signs of early AMD were found in subjects as young as 25 years, with the risk for early AMD features increasing linearly by years of age in men, and, less consistent with a linear increase, in women. Risk for early AMD features increased linearly by pack years of smoking in men, not in women, nor was there any association with other lifestyle or metabolic factors. By providing much sought-after prevalence estimates for AMD from Central Europe, our data underscores a substantial proportion of the adult population with signs of early AMD, including individuals younger than 50 years. This supports the notion that early AMD features in the young might be under-acknowledged.

Mediterranean Diet Score and Its Association with Age-Related Macular Degeneration: The European Eye Study

PURPOSE

To examine associations between adherence to a Mediterranean diet and prevalence of age-related macular degeneration (AMD) in countries ranging from Southern to Northern Europe.

DESIGN

Cross-sectional, population-based epidemiologic study.

PARTICIPANTS

Of 5060 randomly sampled people aged 65 years or older from 7 study centers across Europe (Norway, Estonia, United Kingdom, France, Italy, Greece, and Spain), full dietary data were available in 4753. The mean age of participants was 73.2 years (standard deviation, 5.6), and 55% were women.

METHODS

Participants underwent an eye examination and digital retinal color photography. The images were graded at a single center. Dietary intake during the previous 12 months was assessed by using a semiquantitative food-frequency questionnaire (FFQ). A previously published Mediterranean Diet Score (MDS) was used to classify participants according to their responses on the FFQ. Multivariable logistic regression was used to investigate the association of the MDS score and AMD, taking account of potential confounders and the multicenter study design.

MAIN OUTCOME MEASURES

Images were graded according to the International Classification System for age-related maculopathy and stratified using the Rotterdam staging system into 5 exclusive stages (AMD 0-4) and a separate category of large drusen (≥125 μm). Age-related macular degeneration 4 included neovascular AMD (nvAMD) and geographic atrophy (GA).

RESULTS

Increasing MDS was associated with reduced odds of nvAMD in unadjusted and confounder-adjusted analysis. Compared with the lowest MDS adherence (≤4 score), those in the highest category MDS adherence (>6 score) showed lower odds of nvAMD (odds ratio, 0.53; 0.27-1.04; P trend = 0.01). The association with MDS did not differ by Y204H risk allele (P = 0.89). For all early AMD (grade 1-3), there was no relationship with MDS (P trend = 0.9). There was a weak trend (P = 0.1) between MDS and large drusen; those in the highest category of MDS had 20% reduced odds compared with those in the lowest (P = 0.05).

CONCLUSIONS

This study adds to the limited evidence of the protective effect of adherence to a Mediterranean dietary pattern in those with late AMD, although it does not support previous reports of a relationship with genetic susceptibility. Interventions to encourage the adoption of the Mediterranean diet should be developed, and methods by which such behavior change can be achieved and maintained investigated.

Precursors of age-related macular degeneration: associations with vitamin A and interaction with CFHY402H in the Inter99 Eye Study

PURPOSE

To investigate associations of very early age-related macular degeneration (AMD) with daily intake of vitamin A, beta-carotene, vitamin E, vitamin C, zinc and copper and interactions with AMD-associated polymorphisms in complement factor H (CFHY402H) and ARMS2/LOC387715.

METHODS

Cross-sectional study of 848 subjects aged 30-60 years from the Inter99 Eye Study. Daily intake of vitamins and minerals was estimated from a 198-item food frequency questionnaire. Digital fundus photographs were recorded in red-free illumination and graded for macular drusen >63 μm and numerous (>20) small hard macular drusen as a mean of both eyes.

RESULTS

Higher intake of vitamin A increased the risk of having macular drusen >63 μm with odds ratio = 1.82 (CI₉₅ 1.02-3.24, p = 0.042) comparing participants in the highest quartile of vitamin A intake with participants in the lowest quartile, adjusted for recruitment group, age and sex. There was a significant interaction with CFHY402H (p = 0.038). Among 504 participants with CFHY402H, the relative risk of having macular drusen >63 μm was increased in participants in the highest quartile of vitamin A intake (odds ratio = 2.58; CI₉₅ 1.16-5.73, p = 0.020) and in the second highest quartile (odds ratio = 3.27; CI₉₅ 1.50-7.13, p = 0.0029) compared with the lowest quartile. Further adjusting for total fat intake, energy intake, plasma cholesterol, body mass index (BMI), smoking, alcohol intake, education and physical activity strengthened the association.

CONCLUSIONS

In this cross-sectional study, a higher intake of vitamin A increased the risk of macular drusen >63 μm in subjects with CFHY402H. The study supports that vitamin A may be a risk factor for early AMD.

The Association between the Lipids Levels in Blood and Risk of Age-Related Macular Degeneration

Lipid metabolism may be involved in the pathogenic mechanism of age-related macular degeneration (AMD). However, conflicting results have been reported in the associations of AMD with blood lipids. We performed a meta-analysis including a total of 19 studies to evaluate associations between blood lipids and this disease. The result reported that the high level of high-density lipoprotein cholesterol (HDL-C) obtained with an increment of 1 mmol/L could result in a significantly increase in the AMD risk of approximately 18% (relative risk (RR), 1.18; 95% confidence interval (CI), 1.01 to 1.35; I² = 53.8%; p = 0.007). High levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG) were significantly associated with a decreased risk of AMD (RRs ranging from 0.92 to 0.95; all p < 0.05). The stratified analysis based on AMD subtypes showed that these blood lipids were only significantly associated with the risk of early AMD (all p < 0.05). The association between the blood lipids and AMD risk did not differ substantially based on the other characteristics of the participants. A high HDL-C level was associated with an increased AMD risk, whereas participants with high TC, LDL-C, and TG concentrations may show a decreased risk for this disease. Further well-designed large studies are warranted to confirm the conclusions.

Ex Vivo Confocal Spectroscopy of Autofluorescence in Age-Related Macular Degeneration

Purpose

We investigated the autofluorescence (AF) signature of the microscopic features of retina with age-related macular degeneration (AMD) using 488 nm excitation.

Methods

The globes of four donors with AMD and four age-matched controls were embedded in paraffin and sectioned through the macula. Sections were excited using a 488 nm argon laser, and the AF emission was captured using a laser scanning confocal microscope (496–610 nm, 6 nm resolution). The data cubes were then analyzed to compare peak emission spectra between the AMD and the controls. Microscopic features, including individual lipofuscin and melanolipofuscin granules, Bruch’s Membrane, as well macroscopic features, were considered.

Results

Overall, the AMD eyes showed a trend of blue-shifted emission peaks compared with the controls. These differences were statistically significant when considering the emission of the combined RPE/Bruch’s Membrane across all the tissue cross-sections (p = 0.02).

Conclusions

The AF signatures of ex vivo AMD RPE/BrM show blue-shifted emission spectra (488 nm excitation) compared with the control tissue. The magnitude of these differences is small (~4 nm) and highlights the potential challenges of detecting these subtle spectral differences in vivo.

Age-related macular degeneration in Portugal: prevalence and risk factors in a coastal and an inland town. The Coimbra Eye Study - Report 2

PURPOSE

To determine the age- and sex-specific prevalence of early and late age-related macular degeneration (AMD) in two Portuguese population-based samples and to identify its risk factors.

POPULATION

A population of 6023 adults aged ≥55 years was recruited from two Portuguese primary healthcare units in the central region of Portugal - one from a coastal (n = 3000) and another from an inland town (n = 3023).

METHODS

Cross-sectional population-based study. Participants were enrolled in the two locations between August 2009 and October 2013. Responders underwent standardized interviews and ophthalmologic examination, including digital fundus imaging. All fundus photographs were graded according to an International Classification and Grading System. The main outcome measures consisted of age- and sex-adjusted prevalence of early and late AMD. Potential epidemiologic risk factors were also evaluated using logistic regression analysis.

RESULTS

Of the 6023 subjects enrolled, 5996 had gradable fundus images and were included in the analysis. The crude prevalence of early and late AMD was 6.99 and 0.67%, respectively, for the coastal town and 15.39 and 1.29% for the inland town. Age- and sex-adjusted prevalence of any AMD for the Portuguese population was 12.48% (95% CI: 11.61-13.33) with late AMD accounting for 1.16% (95% CI: 0.85-1.46). Neovascular AMD (NV-AMD) and geographic atrophy (GA) accounted for 0.55% (95% CI: 0.36-0.75) and 0.61% (95% CI: 0.37-0.84) of individuals, respectively. After adjusting for possible confounding factors, prevalence of early and late AMD increased with increasing age (OR = 1.35; 95% CI: 1.23-1.49 for early and OR = 3.01; 95% CI: 2.22-4.08 for late AMD, per each decade of age increase, p < 0.001). After adjustment for age, sex, family history, smoking history, hypertension, diabetes and BMI, subjects from the inland town presented a significantly higher OR of early and late AMD than subjects from the coastal town (OR = 2.57, 95% CI: 2.12-3.12, p < 0.001 for early and OR = 2.06, 95% CI: 1.07-3.95, p = 0.029 for late AMD).

CONCLUSIONS

The prevalence of early and late AMD in this Portuguese population was similar to other large-scale population-based cohorts. After controlling for confounders, age and study site of inclusion were significant independent predictors for both early and late forms of the disease. Further analysis will be needed to completely unravel the underlying reasons for this difference regarding geographic location.

Electronic approaches to restoration of sight

Retinal prostheses are a promising means for restoring sight to patients blinded by the gradual atrophy of photoreceptors due to retinal degeneration. They are designed to reintroduce information into the visual system by electrically stimulating surviving neurons in the retina. This review outlines the concepts and technologies behind two major approaches to retinal prosthetics: epiretinal and subretinal. We describe how the visual system responds to electrical stimulation. We highlight major differences between direct encoding of the retinal output with epiretinal stimulation, and network-mediated response with subretinal stimulation. We summarize results of pre-clinical evaluation of prosthetic visual functions in- and ex vivo, as well as the outcomes of current clinical trials of various retinal implants. We also briefly review alternative, non-electronic, approaches to restoration of sight to the blind, and conclude by suggesting some perspectives for future advancement in the field.

AMD-like retinopathy associated with intravenous iron

Iron accumulation in the retina is associated with the development of age-related macular degeneration (AMD). IV iron is a common method to treat iron deficiency anemia in adults, and its retinal manifestations have not hitherto been identified. To assess whether IV iron formulations can be retina-toxic, we generated a mouse model for iron-induced retinal damage. Male C57BL/6J mice were randomized into groups receiving IV iron-sucrose (+Fe) or 30% sucrose (-Fe). Iron levels in neurosensory retina (NSR), retinal pigment epithelium (RPE), and choroid were assessed using immunofluorescence, quantitative PCR, and the Perls' iron stain. Iron levels were most increased in the RPE and choroid while levels in the NSR did not differ significantly in +Fe mice compared to controls. Eyes from +Fe mice shared histological features with AMD, including Bruch's membrane (BrM) thickening with complement C3 deposition, as well as RPE hypertrophy and vacuolization. This focal degeneration correlated with areas of high choroidal iron levels. Ultrastructural analysis provided further detail of the RPE/photoreceptor outer segment vacuolization and Bruch's membrane thickening. Findings were correlated with a clinical case of a 43-year-old patient who developed numerous retinal drusen, the hallmark of AMD, within 11 months of IV iron therapy. Our results suggest that IV iron therapy may have the potential to induce or exacerbate a form of retinal degeneration. This retinal degeneration shares features with AMD, indicating the need for further study of AMD risk in patients receiving IV iron treatment.

Injectable intraocular telescope: Pilot study

PURPOSE

To assess the feasibility of a new injectable telescopic intraocular lens (IOL).

SETTING

London Eye Hospital, London, United Kingdom.

DESIGN

Prospective interventional pilot study.

METHOD

Eyes with bilateral, intermediate, or advanced dry age-related macular degeneration (AMD); preoperative decimal corrected distance visual acuity (CDVA) of 0.25 or less; and improvement with extraocular simulation of the intervention had implantation of 2 IOLs designed for use together in a Galilean telescope configuration (iolAMD). Patients were followed for 4 months. Safety was assessed by monitoring visual acuity, intraocular pressure, specular microscopy, and anterior segment and macular optical coherence tomographies. Fixation stability and macular sensitivity were determined using microperimetry in some eyes.

RESULTS

There were no significant intraoperative or postoperative complications. In 1 eye, an anterior sulcus IOL was replaced; there were no sequelae. The mean endothelial cell density was reduced by 18%. The mean decimal CDVA improved from 0.12 preoperatively to 0.20 at 4 months, a 67% gain. The mean change in spherical equivalent after implantation was -1.5 diopters (D) with 0.5 D of induced astigmatism. Microperimetric testing indicated a magnification effect and a deviation of the retinal image by up to 5 degrees, with improved fixation stability.

CONCLUSIONS

This injectable intraocular miniature telescope appears safe in the short to medium term and capable of improving visual function. No significant issues were encountered regarding candidate eye selection or patient retention and cooperation. Further work is needed to evaluate the safety and efficacy of the device, particularly with respect to daily-living activities and the range of indications.

FINANCIAL DISCLOSURE

Dr. Qureshi has a financial interest in London Eye Hospital Pharma. No other author has a financial or proprietary interest in any material or method mentioned.

Update on Clinical Trials in Dry Age-related Macular Degeneration

This review article summarizes the most recent clinical trials for dry age-related macular degeneration (AMD), the most common cause of vision loss in the elderly in developed countries. A literature search through websites https://www.pubmed.org and https://www.clinicaltrials.gov/, both accessed no later than November 04, 2015, was performed. We identified three Phase III clinical trials that were completed over the recent 5 years Age-Related Eye Disease Study 2 (AREDS2), implantable miniature telescope and tandospirone, and several other trials targeting a variety of mechanisms including, oxidative stress, complement inhibition, visual cycle inhibition, retinal and choroidal blood flow, stem cells, gene therapy, and visual rehabilitation. To date, none of the biologically oriented therapies have resulted in improved vision. Vision improvement was reported with an implantable mini telescope. Stem cells therapy holds a potential for vision improvement. The AREDS2 formulas did not add any further reduced risk of progression to advanced AMD, compared to the original AREDS formula. Several recently discovered pathogenetic mechanisms in dry AMD have enabled development of new treatment strategies, and several of these have been tested in recent clinical trials and are currently being tested in ongoing trials. The rapid development and understanding of pathogenesis holds promise for the future.

Management of Neovascular Age-related Macular Degeneration: A Review on Landmark Randomized Controlled Trials

In the last decade, a number of prospective clinical trials with carefully designed study protocols have been conducted for the treatment of neovascular age-related macular degeneration (AMD). These landmark clinical trials such as ANCHOR and MARINA and, more recently, the Comparison of AMD Treatment Trials and VIEW studies have revolutionized the management of neovascular AMD. While AMD continues to remain a leading cause of severe visual loss worldwide, advances in pharmacotherapeutics have led to substantial improvements in the outcome of these patients. The introduction of anti-vascular endothelial growth factor agents has resulted in improvement of visual outcomes and has had a positive impact on the quality of life among elderly population. While the contemporary management of neovascular AMD has been successful in tremendously reducing the visual morbidity, the financial burden of therapy has increased exponentially. To overcome these challenges, newer pharmacologic agents are evaluated for their efficacy and safety in AMD. Ground-breaking advances in bench to bedside research have led to discovery of new pathways that appear to be viable targets for preventing visual loss in AMD. In this review, study designs and results of landmark clinical trials in AMD from the past decade have been summarized.

Association of Anti-VEGF Injections with Progression of Geographic Atrophy

Age-related macular degeneration (AMD) is one of the leading causes of blindness in developed countries in people over the age of 60 years. One of the forms of advanced AMD is wet AMD. Wet AMD is a result of leakage and bleeding from abnormal neovascularization. The principal treatment for wet AMD is intravitreal anti-VEGF injections. A second form of advanced AMD is geographic atrophy (GA). GA refers to large areas of retinal pigment epithelium loss. In the literature, there is some concern that anti-VEGF injections administered to treat wet AMD may be associated with progression of GA. This review discusses evidence suggesting the association of anti-VEGF injections with progression of GA.

Statins for age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a progressive, late-onset disorder of the macula affecting central vision. It is the leading cause of blindness in people over 65 years in industrialized countries. Recent epidemiologic, genetic, and pathological evidence has shown that AMD shares a number of risk factors with atherosclerosis, leading to the hypothesis that statins may exert protective effects in AMD.

OBJECTIVES

The objective of this review was to examine the effectiveness of statins compared with other treatments, no treatment, or placebo in delaying the onset and progression of AMD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 3), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to March 2016), EMBASE (January 1980 to March 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to March 2016), PubMed (January 1946 to March 2016), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) (last searched 5 June 2014), ClinicalTrials.gov (www.clinicaltrials.gov), and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 31 March 2016.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-randomized trials that compared statins with other treatments, no treatment, or placebo in people who were diagnosed as having the early stages of AMD.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently evaluated the search results against the selection criteria, abstracted data, and assessed risk of bias. We did not perform meta-analysis due to heterogeneity in the interventions and outcomes between the included studies.

MAIN RESULTS

Two RCTs with a total of 144 participants met the selection criteria. Both trials compared simvastatin versus placebo in older people (older than 50 or 60 years) with high risk of developing AMD (drusen present on examination). Overall, we judged the quality of the evidence to be low, as we downgraded all outcomes due to limitations in the designs of the trials and insufficient outcome reporting. The larger trial, with 114 participants, was conducted in Australia and used a higher dose (40 mg daily) of simvastatin for three years. Participants and study personnel in this trial were adequately masked, however data were missing for 30% of participants at three years' follow-up. The smaller trial, with 30 participants, was conducted in Italy and used a lower dose (20 mg) of simvastatin for three months. This trial reported insufficient details to assess the risk of bias.Neither trial reported data for change in visual acuity. Low-quality evidence from the smaller trial, with 30 participants, did not show a statistically significant difference between the simvastatin and placebo groups in visual acuity values at three months of treatment (decimal visual acuity 0.21 ± 0.56 in simvastatin group and 0.19 ± 0.40 in placebo group) or 45 days after the completion of treatment (decimal visual acuity 0.20 ± 0.50 in simvastatin group and 0.19 ± 0.48 in placebo group). The lack of a difference in visual acuity was not explained by lens or retina status, which remained unchanged during and after the treatment period for both groups.Preliminary analyses of 42 participants who had completed 12 months' follow-up in the larger trial did not show a statistically significant difference between simvastatin and the placebo groups for visual acuity, drusen score, or visual function (effect estimates and confidence intervals were not available). Complete data for these outcomes at three years' follow-up were not reported. At three years, low-quality evidence showed an effect of simvastatin in slowing progression of AMD compared with placebo to be uncertain (odds ratio 0.51, 95% confidence interval 0.23 to 1.09).One trial did not report adverse outcomes. The second trial reported no difference between groups in terms of adverse events such as death, muscle aches, and acute hepatitis.

AUTHORS' CONCLUSIONS

Evidence from currently available RCTs is insufficient to conclude that statins have a role in preventing or delaying the onset or progression of AMD.