Risk factors in age-related maculopathy complicated by choroidal neovascularization

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

Topic

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

Clinical Relevance

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

Methods

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

Results

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

Conclusion

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

Financial Disclosures

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

Elastin Layer in Bruch's Membrane as a Target for Immunization or Tolerization to Modulate Pathology in the Mouse Model of Smoke-Induced Ocular Injury

Age-related macular degeneration (AMD) is associated with an overactive complement system and an increase in circulating antibodies. Our search for potential neoantigens that can trigger complement activation in disease has led us to investigate elastin. A loss of the elastin layer (EL) of Bruch's membrane (BrM) has been reported in aging and AMD together with an increase of serum elastin-derived peptides and α-elastin antibodies. In the mouse model of cigarette smoke exposure (CSE), damage in BrM, loss of the EL, and vision loss are dependent on complement activation. We have examined the hypothesis that CSE generates immunogenic elastin neoepitopes that trigger an increase in α-elastin IgG and IgM antibodies, which can then bind to the neoepitopes in the target cells or membranes, triggering complement activation. Specifically, we showed that immunization with elastin peptide oxidatively modified by cigarette smoke (ox-elastin) exacerbated ocular pathology and vision loss in CSE mice. In contrast, mice receiving peptide immunotherapy (PIT) with ox-elastin did not lose vision over the smoking period and exhibited a more preserved BrM. Immunization and PIT correlated with humoral immunity and complement activation and IgG/IgM deposition in the RPE/BrM/choroid. Finally, PIT modulated immune markers IFNγ and IL-4. The data further support the hypothesis that complement activation, triggered by immune complex formation in target tissues, plays a role in ocular damage in the CSE model. As PIT with ox-elastin peptides reduces damage, we discuss the possibility that AMD progression might be preventable.

Elastin turnover in ocular diseases: A special focus on age-related macular degeneration

The extracellular matrix (ECM) and its turnover play a crucial role in the pathogenesis of several inflammatory diseases, including age-related macular degeneration (AMD). Elastin, a critical protein component of the ECM, not only provides structural and mechanical support to tissues, but also mediates several intracellular and extracellular molecular signaling pathways. Abnormal turnover of elastin has pathological implications. In the eye elastin is a major structural component of Bruch's membrane (BrM), a critical ECM structure separating the retinal pigment epithelium (RPE) from the choriocapillaris. Reduced integrity of macular BrM elastin, increased serum levels of elastin-derived peptides (EDPs), and elevated elastin antibodies have been reported in AMD. Existing reports suggest that elastases, the elastin-degrading enzymes secreted by RPE, infiltrating macrophages or neutrophils could be involved in BrM elastin degradation, thus contributing to AMD pathogenesis. EDPs derived from elastin degradation can increase inflammatory and angiogenic responses in tissues, and the elastin antibodies are shown to play roles in immune cell activity and complement activation. This review summarizes our current understanding on the elastases/elastin fragments-mediated mechanisms of AMD pathogenesis.

The Association Between Diabetic Retinopathy and the Prevalence of Age-Related Macular Degeneration—The Kailuan Eye Study

This study aimed to investigate the prevalence of age-related macular degeneration (AMD) in patients with diabetes mellitus (DM) and diabetic retinopathy (DR) and analyze whether DR is a risk factor for AMD. This population-based epidemiological study included 14,440 people from the Kailuan Eye Study in 2016, of whom 1,618 were patients with type 2 DM aged over 50 years, and 409 had DM with DR. We analyzed whether there were differences in the prevalence of AMD between DM with DR and DM without DR, and conducted a hierarchical statistical analysis according to different stages of DR. Using variable regression analysis, we explored whether DR constituted a risk factor for AMD. In the DM population, the prevalence of wet AMD in patients with DM with and without DR was 0. 3 and 0.2%, respectively, with no significant difference (P = 0.607). Meanwhile, the prevalence of dry AMD in patients with DM with and without DR was 20.8 and 16.0%, respectively, with a significant difference. In the subgroup analysis of dry AMD, the prevalence of early, middle, and late dry AMD in DM with DR was 14.4, 5.9, and 0.5%, respectively. In DM without DR, the prevalence of early, middle, and late dry AMD was 10.5, 4.8, and 0.7%, respectively (P = 0.031). In the subgroup analysis of DR staging, statistical analysis could not be performed because of the limited number of patients with PDR. In the variable regression analysis of risk factors for dry AMD, after adjusting for age, sex, body mass index, hypertension, and dyslipidemia, DR constituted the risk factor for dry AMD. In conclusion, DM did not constitute a risk factor for AMD, and the prevalence of wet AMD and dry AMD in patients with DM and DR was higher than that in patients with DM without DR (among which dry AMD was statistically significant). Multivariate regression analysis confirmed that DR is an independent risk factor for dry AMD. Reasonable control of DM and slowing down the occurrence and development of DR may effectively reduce the prevalence of AMD in patients with DM.

Association Between Aspirin Usage and Age-Related Macular Degeneration: An Updated Systematic Review and Meta-analysis

Purpose: To investigate the association between long-term use of aspirin and age-related macular degeneration (AMD).

Methods: An updated systematic literature search was conducted in PubMed, Medline, Cochrane Library, and embase from conception to February 26, 2021, without any language restriction. All studies that evaluated the relationship between long-term aspirin use and AMD were included.

Results: In the current study, 16 articles were pooled. Overall, no significant association was observed (estimate ratio = 1.108, 95% confidence interval (CI): 0.886–1.385). When the subgroups were evaluated according to various standards, aspirin use was significantly correlated with AMD in studies with volunteer participants (estimate ratio = 0.899, 95% CI: 0.830–0.974, p < 0.01), studies followed up for >10 years (estimate ratio = 2.206, 95% CI: 2.124–2.292, p < 0.01), duration of aspirin use >10 years (estimate ratio = 2.323, 95% CI: 2.234–2.416, p < 0.01), and cohort studies (estimate ratio = 1.961, 95% CI: 1.893–2.032, p < 0.01).

Conclusion: Therefore, the association of aspirin and AMD can be demonstrated with a long-term follow-up or aspirin use, appropriate study design and participant source. The findings in our study might provide practical information on intervention strategies.

Peptide-based immunotherapy against oxidized elastin ameliorates pathology in mouse model of smoke-induced ocular injury

PURPOSE

Age-related macular degeneration (AMD), the leading cause of blindness in western populations, is associated with an overactive complement system, and an increase in circulating antibodies against certain epitopes, including elastin. As loss of the elastin layer of Bruch's membrane (BrM) has been reported in aging and AMD, we previously showed that immunization with elastin peptide oxidatively modified by cigarette smoke (ox-elastin), exacerbated ocular pathology in the smoke-induced ocular pathology (SIOP) model. Here we asked whether ox-elastin peptide-based immunotherapy (PIT) ameliorates damage.

METHODS

C57BL/6J mice were injected with ox-elastin peptide at two doses via weekly subcutaneous administration, while exposed to cigarette smoke for 6 months. FcγR-/- and uninjected C57BL/6J mice served as controls. Retinal morphology was assessed by electron microscopy, and complement activation, antibody deposition and mechanisms of immunological tolerance were assessed by Western blotting and ELISA.

RESULTS

Elimination of Fcγ receptors, preventing antigen/antibody-dependent cytotoxicity, protected against SIOP. Mice receiving PIT with low dose ox-elastin (LD-PIT) exhibited reduced humoral immunity, reduced complement activation and IgG/IgM deposition in the RPE/choroid, and largely a preserved BrM. While there is no direct evidence of ox-elastin pathogenicity, LD-PIT reduced IFNγ and increased IL-4 within RPE/choroid. High dose PIT was not protective.

CONCLUSIONS

These data further support ox-elastin role in ocular damage in part via elastin-specific antibodies, and support the corollary that PIT with ox-elastin attenuates ocular pathology. Overall, damage is associated with complement activation, antibody-dependent cell-mediated cytotoxicity, and altered cytokine signature.

Lipid accumulation and protein modifications of Bruch's membrane in age-related macular degeneration

Age-related macular degeneration (AMD) is a progressive retinal disease, which is the leading cause of blindness in western countries. There is an urgency to establish new therapeutic strategies that could prevent or delay the progression of AMD more efficiently. Until now, the pathogenesis of AMD has remained unclear, limiting the development of the novel therapy. Bruch's membrane (BM) goes through remarkable changes in AMD, playing a significant role during the disease course. The main aim of this review is to present the crucial processes that occur at the level of BM, with special consideration of the lipid accumulation and protein modifications. Besides, some therapies targeted at these molecules and the construction of BM in tissue engineering of retinal pigment epithelium (RPE) cells transplantation were listed. Hopefully, this review may provide a reference for researchers engaged in pathogenesis or management on AMD.

The Association of Aspirin Use with Age-Related Macular Degeneration Progression in the Age-Related Eye Disease Studies: Age-Related Eye Disease Study 2 Report No. 20

PURPOSE

To analyze the potential association between aspirin use and progression of age-related macular degeneration (AMD).

DESIGN

Two prospective cohort studies within 2 controlled clinical trials of oral supplementation for age-related eye disease.

PARTICIPANTS

Age-Related Eye Disease Study (AREDS) participants 55 to 80 years of age and AREDS2 participants 50 to 85 years of age.

METHODS

Propensity scores for aspirin use were calculated for AREDS and AREDS2 participants separately by logistic regression. Of the participants without late AMD (geographic atrophy [GA] or neovascular AMD) in either eye at study baseline, aspirin users were matched 1:1 with nonusers by propensity score (separately for AREDS and AREDS2). Proportional hazards regression was performed, adjusting for age, on the matched participants to evaluate associations between aspirin propensity score and progression to late AMD (and its subtypes).

MAIN OUTCOME MEASURES

Progression to late AMD on color fundus photographs, graded centrally.

RESULTS

Of the 3734 eligible AREDS participants, 1049 (28.1%) were taking aspirin, and of the 2403 eligible AREDS2 participants, 1198 (49.9%) were taking aspirin. After matching by propensity score, the characteristics of the users and nonusers were similar in both studies. Of the 1950 matched AREDS participants and 1694 matched AREDS2 participants, over a median follow-up of 10.1 years and 5.0 years, respectively, the numbers who progressed to late AMD, GA, or neovascular AMD were 454 (23.3%), 345 (17.7%), and 278 (14.3%), respectively, in AREDS and 643 (38.0%), 402 (24.6%), and 341 (20.1%) in AREDS2. The hazard ratios of progression in quintile 5 (highest propensity for aspirin use) versus 1 (reference) were 1.17 (P = 0.35), 1.24 (0.25), and 0.95 (0.81), respectively, in AREDS and 1.26 (0.09), 1.46 (0.03), and 1.12 (0.58) in AREDS2. No significant association with progression to late AMD was observed for quintiles 2 through 5 for any of the 3 outcomes in either study.

CONCLUSIONS

Aspirin use was not associated significantly with progression to late AMD or its subtypes in either the AREDS or AREDS2. Patients with AMD need not avoid aspirin for this reason when its use is medically indicated.

Increased High-Density Lipoprotein Levels Associated with Age-Related Macular Degeneration: Evidence from the EYE-RISK and European Eye Epidemiology Consortia

PURPOSE

Genetic and epidemiologic studies have shown that lipid genes and high-density lipoproteins (HDLs) are implicated in age-related macular degeneration (AMD). We studied circulating lipid levels in relationship to AMD in a large European dataset.

DESIGN

Pooled analysis of cross-sectional data.

PARTICIPANTS

Individuals (N = 30 953) aged 50 years or older participating in the European Eye Epidemiology (E3) consortium and 1530 individuals from the Rotterdam Study with lipid subfraction data.

METHODS

AMD features were graded on fundus photographs using the Rotterdam classification. Routine blood lipid measurements, genetics, medication, and potential confounders were extracted from the E3 database. In a subgroup of the Rotterdam Study, lipid subfractions were identified by the Nightingale biomarker platform. Random-intercepts mixed-effects models incorporating confounders and study site as a random effect were used to estimate associations.

MAIN OUTCOME MEASURES

AMD features and stage; lipid measurements.

RESULTS

HDL was associated with an increased risk of AMD (odds ratio [OR], 1.21 per 1-mmol/l increase; 95% confidence interval [CI], 1.14-1.29), whereas triglycerides were associated with a decreased risk (OR, 0.94 per 1-mmol/l increase; 95% CI, 0.91-0.97). Both were associated with drusen size. Higher HDL raised the odds of larger drusen, whereas higher triglycerides decreases the odds. LDL cholesterol reached statistical significance only in the association with early AMD (P = 0.045). Regarding lipid subfractions, the concentration of extra-large HDL particles showed the most prominent association with AMD (OR, 1.24; 95% CI, 1.10-1.40). The cholesteryl ester transfer protein risk variant (rs17231506) for AMD was in line with increased HDL levels (P = 7.7 × 10-7), but lipase C risk variants (rs2043085, rs2070895) were associated in an opposite way (P = 1.0 × 10-6 and P = 1.6 × 10-4).

CONCLUSIONS

Our study suggested that HDL cholesterol is associated with increased risk of AMD and that triglycerides are negatively associated. Both show the strongest association with early AMD and drusen. Extra-large HDL subfractions seem to be drivers in the relationship with AMD, and variants in lipid genes play a more ambiguous role in this association. Whether systemic lipids directly influence AMD or represent lipid metabolism in the retina remains to be answered.

The Association Between Diabetes and Age-Related Macular Degeneration Among the Elderly in Taiwan

OBJECTIVE

To investigate the relationship between diabetes and future development of age-related macular degeneration (AMD).

RESEARCH DESIGN AND METHODS

Longitudinal, retrospective cohort study data for the period between 1997 and 2012 were obtained from the Longitudinal Health Insurance Database (LHID) of Taiwan. The final available 71,904 patients with diabetes and 270,213 patients without diabetes ≥50 years of age were further matched by age, sex, and Charlson comorbidity index. In the end, 54,616 study subjects in each of the diabetes and nondiabetes groups were recruited. The stratified populations of patients with diabetes with diabetic retinopathy (DR) (n = 7,119) versus those with diabetes who do not have DR (n = 7,119) and populations of patients with proliferative DR (PDR) (n = 2,134) versus those with nonproliferative DR (NPDR) (n = 2,134) were also obtained. Competing risk regression models were used to assess the adjusted hazard ratio (HR) and 99% CI. The main outcome measures were the first-ever diagnosis of AMD during the observational period.

RESULTS

The incidences of nonexudative AMD (HR 1.23; P = 0.108) and exudative AMD (HR 1.37; P = 0.023) were not significantly associated with cohorts of persons with diabetes compared with cohorts without diabetes. The stratified analysis showed that nonexudative AMD (HR 3.89; P = 0.001) and exudative AMD (HR 3.42; P < 0.001) were significantly correlated to diabetes with DR cohorts, compared with diabetes without DR cohorts. The incidences of nonexudative AMD (HR 0.53; P = 0.277) and exudative AMD (HR 2.27; P = 0.058) were not significantly different between PDR cohorts compared with NPDR cohorts.

CONCLUSIONS

This study provides large-scale, population-based evidence that diabetes with retinopathy is independently associated with an increased risk of subsequent AMD development.

Long-Term Regular Use of Low-Dose Aspirin and Neovascular Age-Related Macular Degeneration: National Sample Cohort 2010-2015

PURPOSE

The association between long-term cardioprotective aspirin use and neovascular age-related macular degeneration (AMD) is controversial. This study was undertaken to estimate the risk of neovascular AMD with long-term regular use of low-dose aspirin.

DESIGN

Retrospective population-based study, using a nationwide cohort from a variety of clinics and hospitals in South Korea.

PARTICIPANTS

Nonregular aspirin users and regular aspirin users under national health insurance, aged ≥45 years, who were followed from 2010 to 2015, were identified.

METHODS

Incidence per 10 000 person-years for neovascular AMD was estimated. Long-term regular use of low-dose aspirin was defined as sustained intake of ≤100 mg aspirin with ≥1044 days prescription between 2005 and 2009. Nonregular aspirin users included occasional users or nonusers. The analyses included a propensity score-adjusted analysis in a large, randomly selected, unmatched whole cohort (n = 482 613); propensity score-matched analysis in a matched cohort (n = 74 196); and maximally adjusted analysis in the unmatched whole cohort (n = 482 613).

MAIN OUTCOME MEASURES

Incidence of newly developed neovascular AMD using the registration code for intractable disease under national health insurance.

RESULTS

Incidence of neovascular AMD was 3.5 among nonregular aspirin users and 7.2 among regular aspirin users per 10 000 person-years in the unmatched whole cohort. However, propensity score-adjusted analyses revealed no association between aspirin use and neovascular AMD (adjusted hazard ratio [HR], 0.98; 95% confidence interval [CI], 0.73-1.30). Likewise, propensity score-matched analyses showed no association; incidences of neovascular AMD were 7.5 and 7.1 among nonregular aspirin users and regular aspirin users (crude HR, 0.94; 95% CI, 0.70-1.28), respectively. A maximally adjusted model, including age, sex, income, residential area, and history of 100 randomly selected types of generic drugs, showed no association (adjusted HR, 0.95; 95% CI, 0.71-1.28).

CONCLUSIONS

We found no association between long-term regular use of low-dose aspirin for 5 years and future incidence of neovascular AMD. Thus, this large-scale study suggests that regular, long-term use of low-dose aspirin appears to be safe with respect to the new development of neovascular AMD.

Systemic and ocular fluid compounds as potential biomarkers in age-related macular degeneration

Biomarkers can help unravel mechanisms of disease and identify new targets for therapy. They can also be useful in clinical practice for monitoring disease progression, evaluation of treatment efficacy, and risk assessment in multifactorial diseases, such as age-related macular degeneration (AMD). AMD is a highly prevalent progressive retinal disorder for which multiple genetic and environmental risk factors have been described, but the exact etiology is not yet fully understood. Many compounds have been evaluated for their association with AMD. We performed an extensive literature review of all compounds measured in serum, plasma, vitreous, aqueous humor, and urine of AMD patients. Over 3600 articles were screened, resulting in more than 100 different compounds analyzed in AMD studies, involved in neovascularization, immunity, lipid metabolism, extracellular matrix, oxidative stress, diet, hormones, and comorbidities (such as kidney disease). For each compound, we provide a short description of its function and discuss the results of the studies in relation to its usefulness as AMD biomarker. In addition, biomarkers identified by hypothesis-free techniques, including metabolomics, proteomics, and epigenomics, are covered. In summary, compounds belonging to the oxidative stress pathway, the complement system, and lipid metabolism are the most promising biomarker candidates for AMD. We hope that this comprehensive survey of the literature on systemic and ocular fluid compounds as potential biomarkers in AMD will provide a stepping stone for future research and possible implementation in clinical practice.

Associations between Rs4244285 and Rs762551 gene polymorphisms and age-related macular degeneration

BACKGROUND

Age-related macular degeneration is the leading cause of blindness in elderly individuals in developed countries. The etiology and pathophysiology of age-related macular degeneration have not been elucidated yet. Knowing that the main pathological change of age-related macular degeneration is formation of drusen containing about 40% of lipids, there have been attempts to find associations between age-related macular degeneration and genes controlling lipid metabolism.

PURPOSE

To determine the frequency of CYP2C19 (G681A) Rs4244285 and CYP1A2 (-163C>A) Rs762551 genotypes in patients with age-related macular degeneration.

METHODS

The study enrolled 150 patients with early age-related macular degeneration and 296 age- and gender-matched healthy controls. The genotyping of Rs4244285 and Rs762551 was carried out by using the real-time polymerase chain reaction method.

RESULTS

The CYP1A2 (-163C>A) Rs762551 C/C genotype was more frequently detected in patients with age-related macular degeneration than in the control group (32.7% vs. 21.6%, p = 0.011) and was associated with an increased risk of developing early age-related macular degeneration (OR = 1.759, 95% CI: 1.133-2.729; p = 0.012). The CYP1A2 (-163C>A) Rs762551 C/A genotype was more frequently documented in the control group compared with patients with age-related macular degeneration (46.3% vs. 30.7%, p = 0.002) and was associated with a decreased risk of having age-related macular degeneration (OR = 0.580. 95% CI: 0.362-0.929, p = 0.023) in the co-dominant model.

CONCLUSION

The study showed that the CYP1A2 (-163C>A) Rs762551 C/C genotype was associated with an increased risk of age-related macular degeneration.

Risk factors and biomarkers of age-related macular degeneration

A biomarker can be a substance or structure measured in body parts, fluids or products that can affect or predict disease incidence. As age-related macular degeneration (AMD) is the leading cause of blindness in the developed world, much research and effort has been invested in the identification of different biomarkers to predict disease incidence, identify at risk individuals, elucidate causative pathophysiological etiologies, guide screening, monitoring and treatment parameters, and predict disease outcomes. To date, a host of genetic, environmental, proteomic, and cellular targets have been identified as both risk factors and potential biomarkers for AMD. Despite this, their use has been confined to research settings and has not yet crossed into the clinical arena. A greater understanding of these factors and their use as potential biomarkers for AMD can guide future research and clinical practice. This article will discuss known risk factors and novel, potential biomarkers of AMD in addition to their application in both academic and clinical settings.

Recent developments in the management of dry age-related macular degeneration

Dry age-related macular degeneration (AMD), also called geographic atrophy, is characterized by the atrophy of outer retinal layers and retinal pigment epithelium (RPE) cells. Dry AMD accounts for 80% of all intermediate and advanced forms of the disease. Although vision loss is mainly due to the neovascular form (75%), dry AMD remains a challenge for ophthalmologists because of the lack of effective therapies. Actual management consists of lifestyle modification, vitamin supplements, and supportive measures in the advanced stages. The Age-Related Eye Disease Study demonstrated a statistically significant protective effect of dietary supplementation of antioxidants (vitamin C, vitamin E, beta-carotene, zinc, and copper) on dry AMD progression rate. It was also stated that the consumption of omega-3 polyunsaturated fatty acids, such as docosahexaenoic acid and eicosapentaenoic acid, has protective effects. Other antioxidants, vitamins, and minerals (such as crocetin, curcumin, and vitamins B9, B12, and B6) are under evaluation, but the results are still uncertain. New strategies aim to 1) reduce or block drusen formation, 2) reduce or eliminate inflammation, 3) lower the accumulation of toxic by-products from the visual cycle, 4) reduce or eliminate retinal oxidative stress, 5) improve choroidal perfusion, 6) replace/repair or regenerate lost RPE cells and photoreceptors with stem cell therapy, and 7) develop a target gene therapy.

Drusen and RPE atrophy automated quantification by optical coherence tomography in an elderly population

PURPOSE

Correlate OCT-derived measures of drusen and retinal pigment epithelium (RPE) atrophy areas (RAs) with demographic features in an elderly population.

PATIENTS AND METHODS

Subjects aged 50 years and older underwent Cirrus OCT scanning. Drusen area and volume were obtained from the macula within a central circle (CC) of 3 mm and a surrounding perifoveal ring (PR) of 3-5 mm, using the RPE analysis software (6.0). RA measurements were generated for the 6 × 6 mm(2) retinal area. Gender, age, smoking status, and systolic blood pressure (SBP) were considered.

RESULTS

A total of 434 eyes were included. RA was larger in women (0.63±0.16 vs 0.26±0.08 mm(2), P=0.05) and with increasing age. The PR drusen area increased with increasing age (P<0.001), whereas the CC drusen area remained stable after the age of 70 years (0.25±0.06 mm(2) for ages 70-79 years and 0.25±0.07 mm(2) for ages >80 years). Drusen volume in the CC was smaller after the age of 80 years (0.009±0.003 mm(3)) compared with the 70- to 79-year-old group (0.02±0.008 mm(3)). Drusen measurements were similar between smokers and nonsmokers, but the PR drusen area (0.29 mm(2), P=0.05) and volume (0.40 mm(3), P=0.005) were correlated with years smoked. RA (0.24 mm(2), P=0.10), PR drusen area (0.29 mm(2), P=0.05), and volume (0.40 mm(3), P=0.005) were found to be directly associated with SBP. There was a high correlation between the eyes of the same subject.

CONCLUSION

OCT-based automated algorithms can be used to analyze and describe drusen and geographic atrophy burden in such population-based studies of elderly patients.

Iris color and associated pathological ocular complications: a review of epidemiologic studies

AIM

To elucidate the associations of iris color with major eye diseases.

METHODS

A systematic search on Medline with coverage up to August 2013 was conducted. Assessment of the quality of studies based on their levels of evidence was in accordance with the Centre for Evidence-Based Medicine, Oxford, United Kingdom.

RESULTS

A relationship between darker iris color and an increased risk of age-related cataract has been reported from cross-sectional studies and prospective cohort studies. There was no consistent evidence supporting a major role of iris color in the development or progression of age-related macular degeneration. The association of iris color with ocular uveal melanoma has been confirmed by a meta-analysis of observational studies previously. The etiologic synergism between light iris color and environmental exposure such as UV the exposure of UV radiation was found. There were no studies evaluating the refractive associations with iris color but there may be a possible link between iris color and myopia.

CONCLUSION

Darker iris color is associated with an increased risk of cataract and a reduced risk of ocular uveal melanoma. The association of iris color with age-related macular degeneration is not confirmed. Ophthalmologists should be aware that the risk of ocular disorders appears to vary by differences in iris color.

Diabetes mellitus and risk of age-related macular degeneration: a systematic review and meta-analysis

Age-related macular degeneration (AMD) is a major cause of severe vision loss in elderly people. Diabetes mellitus is a common endocrine disorder with serious consequences, and diabetic retinopathy (DR) is the main ophthalmic complication. DR and AMD are different diseases and we seek to explore the relationship between diabetes and AMD. MEDLINE, EMBASE, and the Cochrane Library were searched for potentially eligible studies. Studies based on longitudinal cohort, cross-sectional, and case-control associations, reporting evaluation data of diabetes as an independent factor for AMD were included. Reports of relative risks (RRs), hazard ratios (HRs), odds ratio (ORs), or evaluation data of diabetes as an independent factor for AMD were included. Review Manager and STATA were used for the meta-analysis. Twenty four articles involving 27 study populations were included for meta-analysis. In 7 cohort studies, diabetes was shown to be a risk factor for AMD (OR, 1.05; 95% CI, 1.00–1.14). Results of 9 cross-sectional studies revealed consistent association of diabetes with AMD (OR, 1.21; 95% CI, 1.00–1.45), especially for late AMD (OR, 1.48; 95% CI, 1.44–1.51). Similar association was also detected for AMD (OR, 1.29; 95% CI, 1.13–1.49) and late AMD (OR, 1.16; 95% CI, 1.11–1.21) in 11 case-control studies. The pooled ORs for risk of neovascular AMD (nAMD) were 1.10 (95% CI, 0.96–1.26), 1.48 (95% CI, 1.44–1.51), and 1.15 (95% CI, 1.11–1.21) from cohort, cross-sectional and case-control studies, respectively. No obvious divergence existed among different ethnic groups. Therefore, we find diabetes a risk factor for AMD, stronger for late AMD than earlier stages. However, most of the included studies only adjusted for age and sex; we thus cannot rule out confounding as a potential explanation for the association. More well-designed prospective cohort studies are still warranted to further examine the association.

Age-related macular degeneration in the aspect of chronic low-grade inflammation (pathophysiological parainflammation)

The products of oxidative stress trigger chronic low-grade inflammation (pathophysiological parainflammation) process in AMD patients. In early AMD, soft drusen contain many mediators of chronic low-grade inflammation such as C-reactive protein, adducts of the carboxyethylpyrrole protein, immunoglobulins, and acute phase molecules, as well as the complement-related proteins C3a, C5a, C5, C5b-9, CFH, CD35, and CD46. The complement system, mainly alternative pathway, mediates chronic autologous pathophysiological parainflammation in dry and exudative AMD, especially in the Y402H gene polymorphism, which causes hypofunction/lack of the protective complement factor H (CFH) and facilitates chronic inflammation mediated by C-reactive protein (CRP). Microglial activation induces photoreceptor cells injury and leads to the development of dry AMD. Many autoantibodies (antibodies against alpha beta crystallin, alpha-actinin, amyloid, C1q, chondroitin, collagen I, collagen III, collagen IV, elastin, fibronectin, heparan sulfate, histone H2A, histone H2B, hyaluronic acid, laminin, proteoglycan, vimentin, vitronectin, and aldolase C and pyruvate kinase M2) and overexpression of Fcc receptors play role in immune-mediated inflammation in AMD patients and in animal model. Macrophages infiltration of retinal/choroidal interface acts as protective factor in early AMD (M2 phenotype macrophages); however it acts as proinflammatory and proangiogenic factor in advanced AMD (M1 and M2 phenotype macrophages).

Elevated high-density lipoprotein cholesterol and age-related macular degeneration: the Alienor study

Background

Lipid metabolism and particularly high-density lipoprotein (HDL) 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 plasma HDL and other lipids, which may be confounded by the recently reported associations of AMD with HDL-related genes. We explored the association of AMD with plasma lipid levels and lipid-lowering medication use, taking into account most of HDL-related genes associated with AMD.

Methods

The Alienor study is a population-based study on age-related eye diseases performed in 963 elderly residents of Bordeaux (France). AMD was graded from non mydriatic color retinal photographs in three exclusive stages: no AMD (n = 430 subjects, 938 eyes); large soft distinct drusen and/or large soft indistinct drusen and/or reticular drusen and/or pigmentary abnormalities (early AMD, n = 176, 247); late AMD (n = 40, 61). Associations of AMD with plasma lipids (HDL, total cholesterol (TC), Low-density lipoprotein (LDL), and triglycerides (TG)) were estimated using Generalized Estimating Equation logistic regressions. Statistical analyses included 646 subjects with complete data.

Results

After multivariate adjustment for age, sex, educational level, smoking, BMI, lipid-lowering medication use, cardiovascular disease and diabetes, and for all relevant genetic polymorphisms (ApoE2, ApoE4, CFH Y402H, ARMS2 A69S, LIPC rs10468017, LIPC rs493258, LPL rs12678919, ABCA1 rs1883025 and CETP rs3764261), higher HDL was significantly associated with an increased risk of early (OR = 2.45, 95%CI: 1.54–3.90; P = 0.0002) and any AMD (OR = 2.29, 95%CI: 1.46–3.59; P = 0.0003). Association with late AMD was far from statistical significance (OR = 1.58, 95%CI: 0.48–5.17; p = 0.45). No associations were found for any stage of AMD with TC, LDL and TG levels, statin or fibrate drug use.

Conclusions

This study suggests that elderly patients with high HDL concentration may be at increased risk for AMD and, further, that HDL dysfunction might be implicated in AMD pathogenesis.

Prevalence of age-related macular degeneration in a large European cohort: results from the population-based Gutenberg Health Study

BACKGROUND

The aim of this study was to describe the sex- and age-specific prevalence of age-related macular degeneration (AMD) and its correlation with urban or rural residence in a large and relatively young European cohort.

METHODS

We evaluated fundus photographs from participants in the Gutenberg Health Study (GHS), a population-based, prospective, observational, single-centre study in the Rhineland-Palatine region in midwestern Germany. The participants were 35-74 years of age at enrolment. The fundus images were classified as described in the Rotterdam Study and were graded independently by two experienced ophthalmologists (CK and UBK) based on the presence of hard and soft drusen, retinal pigmentary abnormalities, and signs of atrophic or neovascular age-related macular generation (AMD).

RESULTS

Photographs from 4,340 participants were available for grading. Small, hard drusen (<63 μm, stages 0b and 0c) were present in 37.4% of participants (95% confidence interval [CI], stage 0b, 31.6% [30.3-33.7]; stage 0c, 5.8% [5.1-6.5]). Early AMD (soft drusen, pigmentary abnormalities, stages 1-3) was present in 3.8% of individuals in the youngest age group (35-44 years) (95% CI, stage 1a, 0.4% [0.3-0.5%]; stage 1b, 3.2% [2.9-3.5%]; stage 2a, 0.1% [0.1-0.2%]; stage 2b, 0% [0-0.0%]; stage 3, 0.1% [0.1-0.2%]), whereas late AMD (stages 4a and 4b) did not appear in the youngest age group. In all age groups, signs of early AMD were detected in 11.9% of individuals (stage 1a, 2.1% [1.7-2.6]; stage 1b, 8.0% [7.2-8.8]; stage 2a, 1.0% [0.7-1.3]; stage 2b, 0.5% [0.3-0.7]; stage 3, 0.3% [0.2-0.6]). Late AMD (geographic atrophy or neovascular AMD) was found in 0.2% of individuals (stage 4a, 0.1 % [0.0-0.2]; stage 4b, 0.1% [0.0-0.2]). AMD increased significantly with age (odds ratio [OR], 1.09; 95% CI, 1.08-1.10). Sex, iris colour, and residence (rural vs. urban) were not associated with different rates of AMD.

CONCLUSIONS

In this study, the prevalence of AMD increased dramatically with age; however, although AMD is usually thought to occur after age 50, signs of early AMD were found in 3.8% of individuals in the youngest age group (younger than 45 years). This population-based sample is the first to provide substantial epidemiologic data from a large German cohort, including data on macular degeneration in younger age groups and incidence data after recall.

Inhibition of elastin peptide-mediated angiogenic signaling mechanism(s) in choroidal endothelial cells by the α6(IV)NC1 collagen fragment

PURPOSE

The inhibitory effects and mechanism(s) of type IV collagen α-6 chain-derived noncollagenous domain (α6[IV]NC1 or hexastatin) on elastin-derived peptide (EDP)-activated choroidal endothelial cell migration, kinase signaling, and membrane type 1 metalloproteinase (MT1-MMP) activation are explored.

METHODS

Mouse choroidal endothelial cells (MCECs) were incubated in media with soluble EDPs (kappa elastin, mouse elastin, and Val-Gly-Val-Ala-Pro-Gly [VGVAPG] hexapeptide) for different time intervals with or without α6(IV)NC1. The MCECs proliferation, migration, tube formation, MT1-MMP expression, and angiogenic signaling were analyzed in cells subjected to EDP and α6(IV)NC1 treatments. The MCECs also were subjected to EDPs, and specific inhibitors for evaluation of focal adhesion kinase (FAK) and protein kinase B (Akt) phosphorylation.

RESULTS

Kappa elastin, mouse elastin, and VGVAPG enhanced the migration, without affecting the proliferation of MCECs. The α6(IV)NC1 inhibited survival and EDP-activated migration of MCECs. The EDP-activated MCEC tube formation on matrigel also was inhibited by α6(IV)NC1. Further, EDP-activated MT1-MMP expression and FAK/phosphoinositide-3-kinase (PI-3K)/mammalian target of rapamycin (mToR)/Akt phosphorylation in MCECs, were reduced by α6(IV)NC1. The EDP-induced FAK and Akt phosphorylation was blocked by FAK- and Akt-specific inhibitors.

CONCLUSIONS

The EDPs and α6(IV)NC1 are identified to exhibit opposing effects on MCEC angiogenic behavior and signaling. The α6(IV)NC1 inhibited cell survival, EDP-mediated migration, MT1-MMP expression and, FAK/PI-3K/mToR/Akt phosphorylation in MCECs. This work demonstrates α6(IV)NC1 as a prospective endogenous molecule for the treatment of diseases involving choroidal neovascularization in the eye.

Ten-year incidence of age-related macular degeneration according to diabetic retinopathy classification among medicare beneficiaries

PURPOSE

To compare the longitudinal incidence over 10 years of dry and wet age-related macular degeneration (AMD) in a U.S. sample of Medicare beneficiaries with no diabetes mellitus, diabetes mellitus without retinopathy, nonproliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR).

METHODS

Using Medicare claims data, the 10-year incidence of dry and wet AMD from 1995 to 2005 in beneficiaries older than 69 years with newly diagnosed diabetes mellitus (n = 6,621), NPDR (n = 1,307), and PDR (n = 327) compared with each other and matched controls without diabetes for each group.

RESULTS

After controlling for covariates, newly diagnosed NPDR was associated with significantly increased risk of incident diagnosis of dry AMD (hazard ratio, 1.24; 95% confidence interval: 1.08-1.43) and wet AMD (hazard ratio 1.68; 95% confidence interval: 1.23-2.31). Newly diagnosed PDR was associated with significantly increased risk of wet AMD only (hazard ratio 2.15; 95% confidence interval: 1.07-4.33). Diabetes without retinopathy did not affect risk of dry or wet AMD. There was no difference in risk of wet AMD in PDR compared with NPDR.

CONCLUSION

Elderly individuals with NPDR or PDR may be at higher risk of AMD compared to those without diabetes mellitus or diabetic retinopathy.

Diminishing risk for age-related macular degeneration with nutrition: a current view

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. Clinical hallmarks of AMD are observed in one third of the elderly in industrialized countries. Preventative interventions through dietary modification are attractive strategies, because they are more affordable than clinical therapies, do not require specialists for administration and many studies suggest a benefit of micro- and macro-nutrients with respect to AMD with few, if any, adverse effects. The goal of this review is to provide information from recent literature on the value of various nutrients, particularly omega-3 fatty acids, lower glycemic index diets and, perhaps, some carotenoids, with regard to diminishing risk for onset or progression of AMD. Results from the upcoming Age-Related Eye Disease Study (AREDS) II intervention trial should be particularly informative.

Age-related macular degeneration is associated with increased proportion of CD56(+) T cells in peripheral blood

PURPOSE

To examine the association between age-related changes in the T-cell compartment and prevalence of age-related macular degeneration (AMD).

DESIGN

Case-control study.

PARTICIPANTS

A total of 117 AMD cases and 106 controls were included prospectively.

METHODS

Fresh-drawn peripheral blood samples were processed for flow cytometric analysis of T-cell populations. Plasma samples were analyzed for anti-cytomegalovirus (CMV) immunoglobulin (Ig)G and complement factor H (CFH) Y402H genotype. The diagnosis of AMD was made according to the Clinical Age-Related Maculopathy Staging System.

MAIN OUTCOME MEASURES

Association between frequency of aged T cells and prevalence of AMD.

RESULTS

The prevalence of AMD was associated with distinct age-related changes in the T-cell compartment. Specifically, the patients with AMD had an increased frequency of CD28(-) T cells that expressed the CD56 surface marker (patients, 34.9% vs. aged controls, 25.8%; P = 0.002). Participants in the highest tertile of CD56(+) CD28(-) T cells had an odds ratio (OR) for the presence of AMD of 3.2 (95% confidence interval [CI], 1.2-8.8) after adjustment for CFH genotype, anti-CMV IgG positivity, age, sex, and smoking history. The adjusted OR of the presence of AMD for persons having at least 1 CFH H402 risk allele increased from 3.5 (95% CI, 1.5-8.1) to 13.3 (95% CI, 3.3-53.6) for persons with at least 1 CFH H402 risk allele and above the median level of CD56(+) CD28(-) T cells.

CONCLUSIONS

We found increased levels of circulating aged CD56(+) CD28(-) T cells in patients with AMD. Although this supports the notion of AMD as a systemic disease, it also suggests that the adaptive immune system is implicated in its pathogenesis.

Nutritional modulation of age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly worldwide. It affects 30-50 million individuals and clinical hallmarks of AMD are observed in at least one third of persons over the age of 75 in industrialized countries (Gehrs et al., 2006). Costs associated with AMD are in excess of $340 billion US (American-Health-Assistance-Foundation, 2012). The majority of AMD patients in the United States are not eligible for clinical treatments (Biarnes et al., 2011; Klein et al., 2011). Preventive interventions through dietary modulation are attractive strategies because many studies suggest a benefit of micro- and macronutrients with respect to AMD, as well as other age-related debilities, and with few, if any, adverse effects (Chiu, 2011). Preservation of vision would enhance quality of life for millions of elderly people, and alleviate the personal and public health financial burden of AMD (Frick et al., 2007; Wood et al., 2011). Observational studies indicate that maintaining adequate levels of omega-3 fatty acids (i.e. with 2 servings/week of fish) or a low glycemic index diet may be particularly beneficial for early AMD and that higher levels of carotenoids may be protective, most probably, against neovascular AMD. Intervention trials are needed to better understand the full effect of these nutrients and/or combinations of nutrients on retinal health. Analyses that describe effects of a nutrient on onset and/or progress of AMD are valuable because they indicate the value of a nutrient to arrest AMD at the early stages. This comprehensive summary provides essential information about the value of nutrients with regard to diminishing risk for onset or progress of AMD and can serve as a guide until data from ongoing intervention trials are available.

Molecular responses of choroidal endothelial cells to elastin derived peptides through the elastin-binding protein (GLB1)

PURPOSE

Neovascular AMD involves the activation of choroidal endothelial cells to increase their inflammatory and angiogenic behaviors. Elastin derived peptides (EDPs) can elicit some of these phenotypic changes in endothelial cells. This investigation was performed to follow up on those findings by determining a receptor for these peptides in the human eye as well as evaluating the effects of elevated EDPs on choroidal cells in vitro and in vivo.

METHODS

The expression of elastin receptor genes including GLB1 was analyzed using reverse transcription PCR. Migration of choroidal endothelial cells was quantified in the presence of inhibitors to different EDP binding proteins. C57BL6 mice were injected with EDPs and studied by electroretinography, transmission electron microscopy, and microarray analysis.

RESULTS

An alternatively spliced form of beta-galactosidase (GLB1) is present on human choroidal endothelial cells and acts as a receptor for EDPs. Elevated levels of circulating EDPs do not affect retinal function in the mouse, but do increase the expression and deposition of collagen IV in the RPE/choroid complex.

CONCLUSIONS

EDPs may play a role in neovascular AMD by binding to and inducing neovascular phenotypes in choroidal endothelial cells through their receptor, GLB1. These peptides also cause an increased mRNA expression and deposition of collagen IV in the RPE/choroid, which may alter diffusion properties between the retina and choriocapillaris.

Age related macular degeneration and drusen: neuroinflammation in the retina

Inflammation protects from dangerous stimuli, restoring normal tissue homeostasis. Inflammatory response in the nervous system ("neuroinflammation") has distinct features, which are shared in several diseases. The retina is an immune-privileged site, and the tight balance of immune reaction can be disrupted and lead to age-related macular disease (AMD) and to its peculiar sign, the druse. Excessive activation of inflammatory and immunological cascade with subsequent induction of damage, persistent activation of resident immune cells, accumulation of byproducts that exceeds the normal capacity of clearance giving origin to a chronic local inflammation, alterations in the activation of the complement system, infiltration of macrophages, T-lymphocytes and mast-cells from the bloodstream, participate in the mechanisms which originate the drusen. In addition, aging of the retina and AMD involve also para-inflammation, by which immune cells react to persistent stressful stimuli generating low-grade inflammation, aimed at restoring function and maintaining tissue homeostasis by varying the set point in relation to the new altered conditions. This mechanism is also seen in the normal aging retina, but, in the presence of noxious stimuli as in AMD, it can become chronic and have an adverse outcome. Finally, autophagy may provide new insights to understand AMD pathology, due to its contribution in the removal of defective proteins. Therefore, the AMD retina can represent a valuable model to study neuroinflammation, its mechanisms and therapy in a restricted and controllable environment. Targeting these pathways could represent a new way to treat and prevent both exudative and dry forms of AMD.

Ocular hazards of blue-light therapy in dermatology

Blue-light phototherapy has become important in the treatment of many dermatologic conditions and as a result continue to be developed. Although blue-light therapy is successful, research shows that excessive ocular blue-light exposure may contribute to age-related macular degeneration and other vision problems. As blue-light therapy becomes increasingly more popular for clinical and at-home use, patients and operators of blue-light devices should be aware of its associated ocular hazards. Protective eyewear should be carefully selected and implemented with each therapy session to guard against the development of retinal disease.

Lipids and age-related macular degeneration

Given the considerable public health burden imposed by age-related macular degeneration (AMD), much effort has been directed towards elucidating principles of pathogenesis in order to identify risk factors and develop preventive measures and treatments. Together with epidemiological evidence linking cardiovascular risk factors with AMD risk and basic science work examining the role of lipid metabolism in AMD, numerous human studies have assayed a potential relationship between dietary lipids and the development of AMD. We examine the evidence for a role for lipid metabolism in AMD, highlighting key basic biochemical principles, work in animal models, and relevant human studies. The topics of lipoprotein modulation and omega-3 fatty acid intake receive special attention from both a basic science and clinical study standpoint. The evidence suggests that consumption of omega-3 fatty acids, perhaps in concert with antioxidants, may constitute a rational preventative strategy against AMD development, though, absent an appropriately developed double-blind, randomized control trial, insufficient data exist to recommend implementation in the clinical setting at this time.

Clinical risk factors for age-related macular degeneration: a systematic review and meta-analysis

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of blindness in Western countries. Numerous risk factors have been reported but the evidence and strength of association is variable. We aimed to identify those risk factors with strong levels of evidence which could be easily assessed by physicians or ophthalmologists to implement preventive interventions or address current behaviours.

METHODS

A systematic review identified 18 prospective and cross-sectional studies and 6 case control studies involving 113,780 persons with 17,236 cases of late AMD that included an estimate of the association between late AMD and at least one of 16 pre-selected risk factors. Fixed-effects meta-analyses were conducted for each factor to combine odds ratio (OR) and/or relative risk (RR) outcomes across studies by study design. Overall raw point estimates of each risk factor and associated 95% confidence intervals (CI) were calculated.

RESULTS

Increasing age, current cigarette smoking, previous cataract surgery, and a family history of AMD showed strong and consistent associations with late AMD. Risk factors with moderate and consistent associations were higher body mass index, history of cardiovascular disease, hypertension, and higher plasma fibrinogen. Risk factors with weaker and inconsistent associations were gender, ethnicity, diabetes, iris colour, history of cerebrovascular disease, and serum total and HDL cholesterol and triglyceride levels.

CONCLUSIONS

Smoking, previous cataract surgery and a family history of AMD are consistent risk factors for AMD. Cardiovascular risk factors are also associated with AMD. Knowledge of these risk factors that may be easily assessed by physicians and general ophthalmologists may assist in identification and appropriate referral of persons at risk of AMD.

Ocular risk factors for age-related macular degeneration: the Los Angeles Latino Eye Study

PURPOSE

To assess the association between ocular factors and age-related macular degeneration (AMD) in Latinos.

DESIGN

Population-based, cross-sectional study of 6357 self-identified Latinos aged 40 years and older.

METHODS

Ophthalmic examination included subjective refraction, measurement of axial length, evaluation of iris color, Lens Opacities Classification System II (LOCS II) grading of cataracts, and stereoscopic macular photographs for AMD lesions. Generalized estimating equation analysis incorporated data from both eyes to estimate odds ratios (OR) adjusted for covariates.

RESULTS

After controlling for confounders (age, gender, and smoking), prior cataract surgery was associated with advanced AMD (OR, 2.8; 95% CI, 1.01, 7.8), increased retinal pigment (OR, 1.6; 95% CI, 1.02, 1.5), and retinal pigment epithelial depigmentation (OR, 2.2; 95% CI, 1.1, 4.4). The presence of any lens opacity was associated with soft drusen (OR, 1.2; 95% CI, 1.002, 1.5). Longer axial length (per mm) was associated with decreased odds of soft drusen, increased retinal pigment, and geographic atrophy (GA) (ORs, 0.8 [95% CI, 0.7, 0.9], 0.8 [95% CI, 0.7, 0.9], 0.7 [95% CI, 0.5, 0.9], respectively). Myopia was inversely associated with soft drusen (OR, 0.8; 95% CI, 0.7, 0.99). Lighter-colored irises were associated with GA (OR, 5.0; 95% CI, 1.0, 25.3).

CONCLUSIONS

Cross-sectional associations of ocular factors such as cataract, cataract surgery, and refractive errors with early AMD lesions found in Latinos are consistent with those in non-Hispanic Whites. Additionally, prior cataract surgery was associated with advanced AMD.

Cigarette smoking as a risk factor for uveitis

PURPOSE

To determine the association between tobacco smoking history and uveitis.

DESIGN

Retrospective, case-control study.

PARTICIPANTS

A total of 564 patients with ocular inflammation seen in the Proctor Foundation uveitis clinic between 2002 and 2009, and 564 randomly selected patients seen in the comprehensive eye clinic within the same time period.

METHODS

A retrospective medical record review of all cases and controls.

MAIN OUTCOME MEASURES

A logistic regression analysis was conducted with ocular inflammation as the main outcome variable and smoking as the main predictor variable, while adjusting for age, gender, race, and median income.

RESULTS

The odds of a smoker having ocular inflammation were 2.2-fold that of a patient who had never smoked (95% confidence interval [CI], 1.7-3.0; P<0.001). All anatomic subtypes of uveitis were associated with a positive smoking history, with odds ratios (ORs) of 1.7 (95% CI, 1.2-2.4; P = 0.002) for anterior uveitis, 2.7 (95% CI, 1.4-5.6; P = 0.005) for intermediate uveitis, 3.2 (95% CI, 1.3-7.9; P = 0.014) for posterior uveitis, and 3.9 (95% CI, 2.4-6.1; P<0.001) for panuveitis. In patients with panuveitis and cystoid macular edema (CME), the OR was 8.0 (95% CI, 3.3-19.5; P<0.001) compared with 3.1 (95% CI, 1.8-5.2; P<0.001) for patients without CME. Patients with intermediate uveitis and CME also had a higher OR (OR 8.4; 95% CI, 2.5-28.8; P = 0.001) compared with patients without CME (OR 1.5; 95% CI, 0.6-3.8; P = 0.342). Patients with a smoking history were at greater odds of having infectious uveitis (OR 4.5; 95% CI, 2.3-9.0; P<0.001) than noninfectious uveitis (OR 2.1; 95% CI, 1.6-2.8; P<0.001), although both were associated with smoking.

CONCLUSIONS

A history of smoking is significantly associated with all anatomic subtypes of uveitis and infectious uveitis. The association was greater in patients with intermediate uveitis and panuveitis with CME compared with those without CME. In view of the known risks of smoking, these findings, if replicated, would give an additional reason to recommend smoking cessation in patients with uveitis.

Risk factors for age-related maculopathy

Age-related maculopathy (ARM) is the leading cause of blindness in the elderly. Although beneficial therapeutic strategies have recently begun to emerge, much remains unclear regarding the etiopathogenesis of this disorder. Epidemiologic studies have enhanced our understanding of ARM, but the data, often conflicting, has led to difficulties with drawing firm conclusions with respect to risk for this condition. As a consequence, we saw a need to assimilate the published findings with respect to risk factors for ARM, through a review of the literature appraising results from published cross-sectional studies, prospective cohort studies, case series, and case control studies investigating risk for this condition. Our review shows that, to date, and across a spectrum of epidemiologic study designs, only age, cigarette smoking, and family history of ARM have been consistently demonstrated to represent risk for this condition. In addition, genetic studies have recently implicated many genes in the pathogenesis of age-related maculopathy, including Complement Factor H, PLEKHA 1, and LOC387715/HTRA1, demonstrating that environmental and genetic factors are important for the development of ARM suggesting that gene-environment interaction plays an important role in the pathogenesis of this condition.

Sunlight-related factors and the 10-year incidence of age-related maculopathy

PURPOSE

To examine the associations among iris, skin, or hair color, and skin sun sensitivity and the 10-year incidence of age-related maculopathy (ARM).

METHODS

The Blue Mountains Eye Study (BMES) recruited 3654 participants aged 49+ years at baseline (1992-1994, 82.4% participation rate). Re-examinations of 2335 participants (75.1% of survivors) were done after 5 years (1997-1999) and 1952 (76.5% of survivors) after 10 years (2002-2004). Retinal photographs were graded using the Wisconsin ARM Grading System and incident ARM confirmed using the side-by-side grading method. Iris, skin, and hair color, and sun-related skin damage were assessed and skin sun-sensitivity questions were asked at baseline. Ten-year ARM incidence was calculated using Kaplan Meier methods and discrete logistic models were used to assess associations after adjusting for age, sex, and smoking.

RESULTS

After adjustment, no significant associations were found between iris or hair color and either late- or early-incident ARM. Compared to persons with fair skin, those with very fair skin had an increased risk of developing geographic atrophy (multivariate adjusted risk ratio, RR = 7.6; 95% confidence interval, CI = 3.0-19.6). In contrast, compared to persons with average skin sun sensitivity, persons who reported that their skin would usually burn and tan with difficulty had a reduced risk of neovascular ARM (RR = 0.2, 95% CI = 0.0-0.7). Sun-related skin damage was not associated with late or early ARM.

CONCLUSIONS

In this older cohort, we did not find a consistent pattern of association between sunlight-related factors and ARM incidence, except that persons with very fair skin might have an increased risk of geographic atrophy, consistent with our 5-year incidence data. The protective association between skin sensitivity to sun damage and neovascular ARM could have be the result of confounding by sun-avoidance behavior among persons sensitive to sunburn.

Serum cystatin C level, kidney disease markers, and incidence of age-related macular degeneration: the Beaver Dam Eye Study

OBJECTIVE

To examine the associations of the serum cystatin C level and chronic kidney disease with the incidence of age-related macular degeneration (AMD) over 15 years.

METHODS

In this population-based cohort study of 4926 individuals aged 43 to 86 years at baseline, 3779 participated in 1 or more follow-up examinations. Age-related macular degeneration was determined by grading photographs of the macula. Individuals were defined as having mild or moderate to severe chronic kidney disease based on a value of more than 45 mL/min/1.73 m(2) to 60 mL/min/1.73 m(2) or less and 45 mL/min/1.73 m(2) or less, respectively, according to the Modification of Diet in Renal Disease Study equation.

RESULTS

While controlling for age and other risk factors, the level of serum cystatin C at baseline was associated with the incidence of early AMD (odds ratio per log standard deviation [95% confidence interval], 1.16 [1.01-1.35]) and exudative AMD (1.42 [1.03-1.96]) but not geographic atrophy (0.89 [0.56-1.41]) or progression of AMD (1.02 [0.88-1.18]). Mild chronic kidney disease was associated with the 15-year cumulative incidence of early AMD (odds ratio per log standard deviation, 1.36 [95% confidence interval, 1.00-1.86]) but not the incidence of other AMD end points.

CONCLUSION

There is a relationship between the level of serum cystatin C and chronic kidney disease with the incidence of AMD. The underlying biological processes remain to be determined.

Smoking and the risk of age-related macular degeneration: a meta-analysis

PURPOSE

Some studies were undertaken to evaluate the association between cigarette smoking and age-related macular degeneration (AMD). This meta-analysis summarized the risk estimate of smoking and AMD and provided robust evidence for the association.

METHODS

Relevant studies were identified by searching PubMed and MEDLINE (from 1966 to June 2007) and reviewing the reference lists of key articles. The summary relative risk ratio (RR) or odds ratio (OR) and 95% confidence interval (CI) were calculated. Study-specific risk estimates were pooled using a random-effects model.

RESULTS

Five prospective cohort and eight case-control studies met our inclusion criteria. Ever smoking was statistically significant associated with increased risk of AMD among cohort studies (RR, 1.61; 95% CI, 1.01-2.57) or case-control studies (RR, 1.76; 95% CI, 1.56-1.99). Current smokers were at higher risk of AMD than past smokers. Both geographic atrophy (GA) and neovascular AMD (NV) are subtypes of AMD. A significant relationship was found between smoking and GA risk. Smoking increased the risk of NV, with marginal nonsignificance (RR, 1.47; 95% CI, 0.92-2.37) in cohort studies and significance in case-control studies (RR, 1.96; 95% CI, 1.69-2.27).

CONCLUSIONS

This meta-analysis indicated smoking, especially current smoking, was significantly associated with increased risks of AMD and its subtypes.

Elastin-mediated choroidal endothelial cell migration: possible role in age-related macular degeneration

PURPOSE

Endothelial cell (EC) migration is a key event in angiogenesis, and is likely to play an important role in choroidal neovascularization in age-related macular degeneration (AMD). Altered elastin metabolism has been described in AMD, and the present study sought to determine the effects of elastin-derived peptides (EDPs) on choroidal EC migration and proliferation.

METHODS

Migration of the chorioretinal EC line Rf/6a and a primary culture of human choroidal ECs through polycarbonate membrane inserts was quantified in the presence of elastin bioactive hexapeptides (BPs), EDPs, bovine serum albumin (BSA), or balanced salt solution. Proliferation assays and in vitro wound closure experiments were also performed in the presence of elastin fragments or balanced salt solution (control). Elastin overlay experiments were performed on sections of human eyes.

RESULTS

For both Rf/6a and human primary choroidal ECs exposed to EDPs or BPs, the number of ECs that migrated through the polycarbonate membrane was significantly higher than ECs exposed to balanced salt solution alone or to BSA (P < 0.05) in all experiments. In contrast, the rate of EC proliferation did not significantly change in comparison to controls. Elastin binding sites were identified on choroidal ECs in human eyes.

CONCLUSIONS

Elastin fragments increase choroidal EC migration, whereas they do not appear to increase or decrease EC proliferation. Local or systemic abnormalities in elastin physiology may participate in pathologic neovascular membrane formation in AMD.

Macrophages in neovascular age-related macular degeneration: friends or foes?

The events that lead to choroidal neovascularization in eyes with age-related macular degeneration are poorly understood. One possibility that has been explored in a number of studies is that macrophages can promote neovascular changes. In this paper, we summarize the evidence for inflammation in general and macrophages in particular in pathologic neovascularization, and discuss how the diverse functions of these cells may promote or inhibit macular disease. We also discuss some of the conflicting findings regarding the role of macrophages in experimental choroidal neovascularization in mouse models, and suggest areas for future research.

Inflammation, complement factor h, and age-related macular degeneration: the Multi-ethnic Study of Atherosclerosis

OBJECTIVE

To describe the relationship of systemic inflammatory disease, complement factor H (CFH) Y402H (1277T-->C) genotype status and age-related macular degeneration (AMD) prevalence in a multiethnic population of whites, blacks, Hispanics, and Chinese.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

We included 5887 persons aged 45 to 84 years with gradable AMD.

METHODS

Digital fundus photographs were used to measure AMD. Two years earlier, biomarkers of inflammation were measured and history of inflammatory disease and use of antiinflammatory agents obtained.

MAIN OUTCOME MEASURE

Prevalence of AMD.

RESULTS

While controlling for age, gender, race/ethnicity, and study site, there were no associations between systemic inflammatory factors and AMD severity. Higher levels of high-sensitivity C-reactive protein (odds ratio [OR] per standard deviation [SD] increase in natural log [ln] units, 2.34; 95% confidence interval [CI], 1.33-4.13) and interleukin-6 (OR per SD in ln, 2.06; 95% CI, 1.21-3.49) were associated with geographic atrophy but not other AMD end points. History of periodontal disease (OR, 1.68; 95% CI, 1.14-2.47) was related to increased retinal pigment. A history of arthritis was associated with soft distinct drusen (OR, 1.24; 95% CI, 1.06-1.46). A history of oral steroid use was related to large drusen (OR, 2.13; 95% CI, 1.14-3.97) and soft distinct drusen (OR, 1.76; 95% CI, 1.00-3.10) and history of cyclooxygenase 2 inhibitor use were associated with large drusen (OR, 1.50; 95% CI, 1.10-2.04), soft indistinct drusen (OR, 1.84; 95% CI, 1.09-3.10), and large drusen area (OR, 1.66; 95% CI, 1.02-2.71). Whites, blacks, and Hispanics with CFH Y402H CC variant genotype had the highest frequency of early AMD compared with those with wild TT genotype. The frequency of CFH did explain some of the difference in AMD prevalence between Chinese and Hispanics compared with whites, but did not explain the difference in prevalence between whites and blacks.

CONCLUSIONS

This study confirmed associations of the Y402H CFH gene variant with AMD in nonwhite populations, but neither explained the lack of association between inflammatory factors and AMD in the cohort nor the basis for the observed differences in AMD prevalence across ethnic groups.

Increased choroidal neovascularization following laser induction in mice lacking lysyl oxidase-like 1

PURPOSE

Age-related degradation of the elastic lamina in Bruch's membrane may have a permissive effect on the growth of choroidal neovascularization (CNV). This study investigated the influence of defective elastic fiber maintenance in the development of laser-induced CNV.

METHODS

A mouse lacking lysyl oxidase-like (LOXL)-1, an enzyme essential for elastin polymerization, was studied. The morphologic characteristics of the elastic lamina within Bruch's membrane were examined in mutant and wild-type (WT) eyes. Laser-induced CNV was evaluated by fluorescein angiography and choroidal flat mounts. Immunohistochemistry for elastin was performed on the CNV lesions, and vascular endothelial growth factor (VEGF) levels were determined by ELISA. Soluble elastin and matrix metalloproteinase (MMPs) levels were also analyzed by immunoblotting.

RESULTS

The elastic lamina of Bruch's membrane in the LOXL1-deficient mice was fragmented and less continuous than in the WT controls. The mutant mice showed increased levels of soluble elastin peptides and reduced elastin polymer deposition in neovascular membranes. Significantly larger CNV with greater leakage on fluorescein angiography developed in mutant mice. VEGF levels in the RPE/choroid were higher in the knockout mice on days 7 and 14 after laser (P < 0.05). MT1-MMP (MMP14) was also elevated after laser in the LOXL1 mutant eyes compared to the WT controls.

CONCLUSIONS

These results show that a systemic defect in elastic fiber deposition affects Bruch's membrane integrity and leads to more aggressive CNV growth. The latter may be partially mediated by abnormal signaling from the accumulation of soluble elastin peptides.

Role of genetic factors and inflammation in age-related macular degeneration

Complement factor H (CFH) has been implicated in the predisposition to advanced forms of age-related macular degeneration (AMD). The purpose of this review is to highlight recent discoveries implicating single nucleotide polymorphisms on 1q32, 6p21, and 10q26 in the risk for development of AMD. In addition, the central role of CFH in the complement cascade and its role in the inflammatory hypothesis for AMD are reviewed.

High-sensitivity C-reactive protein, other markers of inflammation, and the incidence of macular degeneration in women

OBJECTIVE

To investigate whether high-sensitivity C-reactive protein (hsCRP) and other biomarkers of inflammation predict age-related macular degeneration (AMD).

METHODS

We measured hsCRP, soluble intercellular adhesion molecule-1 (sICAM-1), and fibrinogen levels in baseline plasma samples from 27 687 participants with a mean age of 54.6 years and initially free of AMD in the Women's Health Study. We prospectively ascertained 150 cases of AMD with vision loss of 20/30 or worse in the affected eye by self-report confirmed with review of medical records during 275 852 person-years of follow-up (mean = 10 years) and used proportional hazards models to examine the relationship between these biomarkers and AMD.

RESULTS

After adjustment for multiple risk factors, the hazard ratio (HR) (95% confidence interval [CI]) of AMD, contrasting the highest vs lowest quintile of hsCRP, was 3.09 (1.39-6.88) (P trend = .02). In similar models, the HR (95% CI) for sICAM-1 was 1.87 (0.97-3.58) (P trend = .07). The relationship between fibrinogen and AMD was J-shaped, with an HR (95% CI) of 2.01 (1.07-3.75) for women in the highest fifth vs second fifth.

CONCLUSION

Elevated circulating levels of hsCRP, sICAM-1, and fibrinogen precede the development of visually significant AMD in women, providing further support for the hypothesis that inflammation may play a role in AMD.