Epidemiological association between systemic diseases and age-related macular degeneration: the Korea National Health and Nutrition Examination Survey 2008-2011

Serum 25-Hydroxyvitamin D Is Differentially Associated with Early and Late Age-Related Macular Degeneration in the United States Population

BACKGROUND

Age-related macular degeneration (AMD) has been the leading cause of irreversible blindness in industrialized countries. Emerging data suggest that serum vitamin D levels may be associated with AMD but show mixed results. National-level population data on the relationship between vitamin D and AMD severities are still lacking.

METHODS

We used data from the National Health and Nutrition Examination Survey (NHANES) 2005 to 2008. Retinal photographs were taken and graded for AMD stage. The odds ratio (OR) of AMD and its subtype was calculated after adjusting for confounding factors. Restricted cubic spline (RCS) analyses were used to explore potential non-linear relations.

RESULTS

A total of 5041 participants with a mean age of 59.6 years were included. After adjusting for covariates, participants with higher level of serum 25-hydroxyvitamin D [25(OH)D] had significantly greater odds of early AMD (OR, 1.65; 95% CI, 1.08-2.51) and decreased risk of late AMD (OR, 0.29; 95% CI, 0.09-0.88). When stratified by age, a positive association between the level of serum 25(OH)D and early AMD was present in the <60 years group (OR, 2.79; 95% CI, 1.08-7.29), whereas a negative relation between the level of serum 25(OH)D and late AMD was detected in the ≥60 years group (OR, 0.24; 95% CI, 0.08-0.76).

CONCLUSIONS

A higher level of serum 25(OH)D was related to increased risk of early AMD in those <60 years and decreased risk of late AMD in those ≥60 years.

Liver fibrosis and retinal features in an older Mediterranean population: Results from the Salus in Apulia study

Background

Age is a leading contributor to the liver fibrosis rate and a gradual deterioration of optical function, but this association in older populations is still under-explored. The present study aimed to explore the link between vascular and neural retinal characteristics and the risk of liver fibrosis in 731 older adults from the population-based Salus in Apulia study.

Methods

Retinal features were obtained using optical coherence tomography (OCT) and OCT-angiography (OCT-A). Liver fibrosis risk was taken as the fibrosis-4 (FIB-4) score. Generalized linear models (logistic regression) were used to estimate the association effect between each unit increase of OCT and OCT-A parameters as independent variables and a FIB-4 ≥ 2.67 score as an outcome. Generalized additive models were used to assess the non-linear association between OCT-A features and the linear FIB-4 score.

Results

Increased gangliar cell complex (GCC) thickness was inversely associated with a FIB-4 score above the cut-off in both the raw model (OR: 0.98; 95% CI: 0.96-0.99; SE: 0.01) and after adjustment for age, sex, education, hypertension, diabetes, total cholesterol, and triglycerides (OR: 0.98; 95% CI: 0.97-0.99; SE: 0.01).

Conclusion

Our findings add to the growing volume of scientific literature demonstrating that liver fibrosis is associated with retinal neurodegeneration. This study raises a number of new questions, including whether OCT-A may be used to track the progression of metabolic abnormalities and define exact thresholds for predicting and classifying liver disease.

Association between metformin use and the risk of age-related macular degeneration in patients with type 2 diabetes: a retrospective study

OBJECTIVES

To investigate the effect of metformin on the decreased risk of developing age-related macular degeneration (AMD) in patients with type 2 diabetes mellitus (T2DM) for ≥10 years.

DESIGN

A retrospective study.

PARTICIPANTS

Patients aged ≥50 with a diagnosis of T2DM no less than 10 years were included.

METHODS

Variables predisposing to AMD were reviewed; the potential confounders related to T2DM or AMD were selected from literature records; AMD and diabetic retinopathy (DR) were diagnosed by funduscopy, optical coherence tomography and/or fluorescein angiography. The subgroup analysis was performed in early and late AMD. The protective effect of metformin was evaluated in duration-response and dose-response patterns.

RESULTS

A total of 324 patients (115 metformin non-users and 209 users) were included in the final analysis. AMD was observed in 15.8% of metformin users and 45.2% of metformin non-users (p<0.0001). The ORs for any AMD, early AMD and late AMD present in patients with DR were 0.06 (0.02-0.20), 0.03 (0.00-0.20) and 0.17 (0.04-0.75). The serum high-density lipoprotein level was positively associated with the late AMD risk (p=0.0054). When analysed by the tertiles of cumulative duration, a similarly reduced risk was observed for the second (5-9 years) (OR: 0.24, 95% CI: 0.08 to 0.75) and third tertiles (≥10 years) (OR: 0.22, 95% CI: 0.09 to 0.52) compared with the first tertile (≤4 years).

CONCLUSION

Among patients with T2DM for ≥10 years, metformin users were less likely to develop any AMD and early AMD than non-users; however, the late AMD was not significantly associated with the use of metformin. Also, AMD was less prevalent in patients with DR. The prolonged metformin treatment with a high cumulative dose enhanced the protective effect against AMD. Metformin significantly reduces the AMD risk when the cumulative duration is >5 years.

The Common Antidiabetic Drug Metformin Reduces Odds of Developing Age-Related Macular Degeneration

Purpose

AMD is the leading cause of irreversible blindness in older individuals in the Western world, and there are currently no therapies to halt disease progression. Studies suggest that the commonly prescribed antidiabetic drug, metformin, is associated with decreased risk of several ocular diseases, but no work has investigated the effect of metformin use on development of AMD. Thus, we aim to investigate whether metformin use is associated with decreased risk of developing AMD.

Methods

In this retrospective case-control study, we used medical records from patients older than 55 who have visited a University of Florida health clinic. Three controls were matched for every AMD case, defined by International Classification of Diseases, Ninth Revision code, based on the Charlson Comorbidity Index to ensure comparable baseline overall health status. Univariate and conditional multivariable logistic regressions were used to determine the association between a variety of covariates, including metformin use, and AMD diagnosis.

Results

Metformin use was associated with decreased odds of developing AMD, independently of the other covariates investigated, with an odds ratio of 0.58 and a 95% confidence interval of 0.43 to 0.79. Other medications assessed were not associated with decreased odds of developing AMD.

Conclusions

Patients who had taken metformin had decreased odds of developing AMD, suggesting that metformin may have a therapeutic role in AMD development or progression in those who are at risk. Further work should include clinical trials to investigate prospectively whether metformin has a protective effect in those at risk for developing AMD.

Age-related macular degeneration among the elderly: The 5th National Health and Nutrition Examination Survey, 2010 through 2012

AIM

This study was conducted to identify the prevalence and factors associated with age-related macular degeneration (AMD) in Korean elderly.

METHODS

The study population of this cross-sectional survey was the Korean Health and Nutrition Examination Survey (KHANES) 2010 through 2012, the fifth population-based study.

RESULTS

Analysis of 2,767 elderly (above age 65) from 23,376 participants showed the prevalence of any AMD to be 17.6% in the Korean elderly. Factors that were significantly positively associated with AMD included age, sex, occupation, low socioeconomic status, liver cirrhosis and physical activity (p < .01). Significantly negatively associated with AMD were cardiovascular disease, obesity, and beta-carotene intake (p < .05).

CONCLUSIONS

This study estimated the prevalence rate and assessed factors associated with AMD in the elderly. This can be used to build a strategy for elderly eye health, and provides valuable information for screening for putative risks in the elderly.

INCREASED INCIDENCE OF CUTANEOUS KERATINOCYTIC AND MELANOCYTIC MALIGNANCIES IN PATIENTS WITH AGE-RELATED MACULAR DEGENERATION

PURPOSE

The relationship between age-related macular degeneration (AMD) and malignancy, especially cutaneous malignancies, is not well studied. We investigated a possible association between AMD and cutaneous malignancies.

METHODS

A retrospective, consecutive review of all patients who had received at least 1 intravitreal injection for wet AMD between January 1, 2004, and December 31, 2013, was conducted using the Rochester Epidemiology Project in Olmsted County, Minnesota. Age- and sex-matched control groups included 473 pre-anti-vascular endothelial growth factor era wet AMD patients, 504 concurrent time dry AMD patients, and 504 patients with no AMD. The rates of AMD and overall malignancy, cutaneous malignancies, and specific types of cutaneous malignancies were compared between groups of patients.

RESULTS

Patients with wet AMD incurred an increased rate of overall malignancies compared to patients with dry AMD {52.8% wet AMD (confidence interval [CI]: 48.3-57.2) vs. 43.7% dry AMD (CI: 39.3-48.1); P= 0.003} or those without AMD (52.8% wet AMD [CI: 48.3-57.2] vs. 35.3% no AMD [CI: 31.1-39.7]; P = <0.001). Patients with dry AMD also had higher rates of malignancy than those without AMD (43.7% dry AMD [CI: 39.3-48.1] vs. 35.3% no AMD [CI: 31.1-39.7]; P = 0.007). Rate of cutaneous malignancies was increased in patients with wet AMD compared to patients with dry AMD (24.4% wet AMD [CI: 20.7-28.4] vs. 14.6% dry AMD [CI: 11.5-17.9]; P = <0.001) and those with no AMD (24.4% wet AMD [CI: 20.7-28.4] vs. 9.7% no AMD [CI: 7.3-12.7]; P = <0.001).

CONCLUSION AND RELEVANCE

To the best of our knowledge, this is the first report to establish an association between AMD and cutaneous malignancies, supporting a possible discussion of the association when a patient presents with one of the two conditions.

Pleiotropic Effects of Risk Factors in Age-Related Macular Degeneration and Seemingly Unrelated Complex Diseases

Age-related macular degeneration (AMD) is a complex disease with both environmental and genetic factors influencing disease risk. Genome-wide case-control association studies, candidate gene analyses, and epidemiological studies reinforced the notion that AMD is predominantly a disease of an impaired complement system and an altered high-density lipoprotein (HDL) metabolism. Recent reports demonstrated the pleiotropic role of the complement system and HDL in complex diseases such as cardiovascular disease, autoimmune disorders, cancer, and Alzheimer's disease. In light of these findings, we explore current evidence for a shared genetic and environmental risk of AMD and unrelated complex diseases based on epidemiological studies. Shared risk factors may indicate common pathways in disease pathology and thus may have implications for novel treatment options of AMD pathology.

Choroidal microvascular proliferation secondary to diabetes mellitus

Diabetes is a common endocrine disorder associated with peripheral microvascular diseases such as proliferative retinal microangiopathy (or diabetic retinopathy), which may lead to blindness. Unfortunately, diabetic microvascular abnormalities in the choroid are underestimated in clinical practice. Recent literature has revealed that the severity of diabetic retinopathy is aggravated by choroidopathy resulting from hyperglycemia. Here, we introduce a case of diabetic retinopathy with choroidal neovascularization membrane but without signs of retinal microvascular proliferation or drusen. We investigated the pathogenesis of choroidal microvascular proliferation secondary to diabetes. We postulate that choroidal neovascularization is an intraocular microvascular complication of diabetes mellitus. Intravitreal anti-vascular endothelial growth factor therapy may be a treatment option for microvascular proliferation in both retina and choroids.

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.

Spotlight on reticular pseudodrusen

Age-related macular degeneration (AMD) is a leading cause of vision loss in patients >50 years old. The hallmark of the disease is represented by the accumulation of extracellular material between retinal pigment epithelium and the inner collagenous layer of Bruch's membrane, called drusen. Although identified almost 30 years ago, reticular pseudodrusen (RPD) have been recently recognized as a distinctive phenotype. Unlike drusen, they are located in the subretinal space. RPD are strongly associated with late AMD, especially geographic atrophy, type 2 and 3 choroidal neovascularization, which, in turn, are less common in typical AMD. RPD identification is not straightforward at fundus examination, and their identification should employ at least 2 different imaging modalities. In this narrative review, we embrace all aspects of RPD, including history, epidemiology, histology, imaging, functional test, natural history and therapy.

Attenuation of iron-binding proteins in ARPE-19 cells reduces their resistance to oxidative stress

PURPOSE

Oxidative stress-related damage to retinal pigment epithelial (RPE) cells is an important feature in the development of age-related macular degeneration. Iron-catalysed intralysosomal production of hydroxyl radicals is considered a major pathogenic factor, leading to lipofuscin formation with ensuing depressed cellular autophagic capacity, lysosomal membrane permeabilization and apoptosis. Previously, we have shown that cultured immortalized human RPE (ARPE-19) cells are extremely resistant to exposure to bolus doses of hydrogen peroxide and contain considerable amounts of the iron-binding proteins metallothionein (MT), heat-shock protein 70 (HSP70) and ferritin (FT). According to previous findings, autophagy of these proteins depresses lysosomal redox-active iron. The aim of this study was to investigate whether up- or downregulation of these proteins would affect the resistance of ARPE-19 cells to oxidative stress.

METHODS

The sensitivity of ARPE-19 cells to H2 O2 exposure was tested following upregulation of MT, HSP70 and/or FT by pretreatment with ZnSO4 , heat shock or FeCl3 , as well as siRNA-mediated downregulation of the same proteins.

RESULTS

Upregulation of MT, HSP70 and FT did not improve survival following exposure to H2 O2 . This was interpreted as existence of an already maximal protection. Combined siRNA-mediated attenuation of both FT chains (H and L), or simultaneous downregulation of all three proteins, made the cells significantly more susceptible to oxidative stress confirming the importance of iron-binding proteins.

CONCLUSION

The findings support our hypothesis that the oxidative stress resistance exhibited by RPE cells may be explained by a high autophagic influx of iron-binding proteins that would keep levels of redox-active lysosomal iron low.

Outcomes of intravitreal anti-VEGF therapy in eyes with both neovascular age-related macular degeneration and diabetic retinopathy

PURPOSE

To investigate the outcomes of intravitreal antivascular endothelial growth factor (VEGF) therapy in eyes with both neovascular age-related macular degeneration (AMD) and diabetic retinopathy (DR).

METHODS

Patients from four high-volume referral centres who presented with neovascular AMD and DR, and received intravitreal anti-VEGF therapy, were included. Data retrieved from medical records and multimodal imaging were analysed.

RESULTS

Forty-one eyes of 38 patients (21 male, 17 female; mean age 78±8 years) were enrolled. Median follow-up was 28±19 (12-72) months with a mean of 9.2±7.4 intravitreal anti-VEGF injections per eye were administrated. Best-corrected visual acuity (BCVA) was 0.5±0.3 logMAR; it improved significantly at 1 year (0.3±0.3 logMAR; p=0.02) and returned to baseline values at last follow-up visit (0.6±0.4 logMAR; p=0.26). Mean central macular thickness (CMT) significantly decreased from 408±150 μm to 328±104 μm at 1 year (p=0.021) and to 335±127 μm at last follow-up visit (p=0.032). The baseline severity of DR was graded as mild non-proliferative DR (NPDR) in 21 (51%) eyes, moderate NPDR in 14 (34%), severe NPDR in 4 (10%) and inactive proliferative DR in 2 (5%). At last follow-up visit, one eye graded as moderate NPDR improved to mild, one eye graded as severe NPDR improved to mild and one eye graded as severe NPDR was inactivated due to panretinal photocoagulation.

CONCLUSIONS

Outcomes analysis of intravitreal anti-VEGF therapy for eyes with both neovascular AMD and DR showed stabilisation of BCVA and reduction of CMT, along with stable or improved DR stage throughout follow-up.

An Overview of Ophthalmologic Survey Methodology in the 2008-2015 Korean National Health and Nutrition Examination Surveys

The Korea National Health and Nutrition Examination Survey (KNHANES) is a national program designed to assess the health and nutritional status of the noninstitutionalized population of South Korea. The KNHANES was initiated in 1998 and has been conducted annually since 2007. Starting in the latter half of 2008, ophthalmologic examinations were included in the survey in order to investigate the prevalence and risk factors of common eye diseases such as visual impairment, refractive errors, strabismus, blepharoptosis, cataract, pterygium, diabetic retinopathy, age-related macular degeneration, glaucoma, dry eye disease, and color vision deficiency. The measurements included in the ophthalmic questionnaire and examination methods were modified in the KNHANES IV, V, and VI. In this article, we provide detailed information about the methodology of the ophthalmic examinations in KNHANES in order to aid in further investigations related to major eye diseases in South Korea.

Polypoidal Choroidal Vasculopathy in Asians

Age related macular degeneration (AMD) in Asians has been suggested to differ from their Western counterparts in terms of epidemiology, pathogenesis, clinical presentation and treatment. In particular, polypoidal choroidal vasculopathy (PCV) appears to be the predominant subtype of exudative AMD in Asian populations, in contrast to choroidal neovascularization secondary to AMD (CNV-AMD) in Western populations. Epidemiological data on PCV has been largely limited to hospital-based studies and there are currently no data on the incidence of PCV. Similarities and differences in risk factor profile between PCV and CNV-AMD point to some shared pathogenic mechanisms but also differential underlying mechanisms leading to the development of each phenotype. Serum biomarkers such as CRP, homocysteine and matrix metalloproteinases suggest underlying inflammation, atherosclerosis and deranged extracellular matrix metabolism as possible pathogenic mechanisms. In addition, recent advances in genome sequencing have revealed differences in genetic determinants of each subtype. While the standard of care for CNV-AMD is anti-vascular endothelial growth factor (VEGF) therapy, photodynamic therapy (PDT) has been the mainstay of treatment for PCV, although long-term visual prognosis remains unsatisfactory. The optimal treatment for PCV requires further clarification, particularly with different types of anti-VEGF agents and possible benefits of reduced fluence PDT.