ASSOCIATIONS BETWEEN CARDIOVASCULAR RISK FACTORS AND EARLY AGE-RELATED MACULAR DEGENERATION IN A RURAL CHINESE ADULT POPULATION

Ganglion cell complex changes in wet AMD patients treated with anti-VEGF intravitreal injections according to a treat-and-extend protocol

OBJECTIVE

To analyze changes in ganglion cell complex (GCC) thickness in wet age-related macular degeneration (AMD) patients receiving intravitreal injections.

DESIGN

Retrospective cohort study involving 46 eyes at a single tertiary ophthalmology practice.

PARTICIPANTS

The injection group consisted of wet AMD patients who received intravitreal injections for at least 3 years following a treat-and-extend protocol. Twenty-two patients received ranibizumab, and 1 patient received aflibercept. The control group consisted of dry AMD patients who were observed only and did not receive medical treatment over the same period. GCC thickness and visual acuity were recorded at baseline and at 1-, 2-, and 3-year follow-up visits.

RESULTS

In the injection group, there was a nonsignificant trend toward reduction in GCC thickness over 3 years (-4.09 ± 8.47 µm; p = 0.09). Within the injection group, correlation analysis between the number of intravitreal injections and GCC thickness was nonsignificant but trended toward a direct relationship, with more injections correlated with a relatively thicker GCC at 3 years. There was no significant change in GCC thickness between baseline and year 3 for the control group.

CONCLUSIONS

Study results suggest that that there is no significant GCC thinning in wet AMD patients following a treat-and-extend regimen over 3 years.

Age-related macular degeneration and cardiovascular disease in US population: an observational study

BACKGROUND

As far as we know, age-related macular degeneration (AMD) has become one of the predominant causes of visual impairments. Previous studies have revealed that AMD and many cardiovascular diseases (CVDs) share the same pathologic and genotypic factors, making the connection between AMD and CVD a hot topic. However, the conclusions of the available studies on the relationship between them are somewhat divergent.

METHODS

We screened 5523 eligible participants from the National Health and Nutrition Examination Survey (NHANES) database from 2005 through 2008 for an observational clinical study design. Binary logistic regression modelling was used to estimate the relations between AMD and various CVDs with and without adjustment for demographics, health status, and behaviours related to health.

RESULTS

Binary logistic regression analyses showed that AMD was able to increase the risk of CVDs in patients both unadjusted and after adjusting for confounding variables.

CONCLUSIONS

Within this study, preventing the development of AMD might cut down the incidence of several CVDs, in particular, significantly lowering the stroke risk. These findings indicate that interventions to prevent AMD may also help to prevent CVDs. In general, late AMD has a more severe impact on the risk of CVDs compared with early AMD. These results could help clinical ophthalmology and cardiovascular medicine in their clinical education and interventions.

Epidemiology of geographic atrophy and its precursor features of intermediate age-related macular degeneration

Globally age-related macular degeneration (AMD) is a leading cause of blindness with a significant impact on quality of life. Geographic atrophy (GA) is the atrophic late form of AMD and its prevalence increases markedly with age with around 1 in 5 persons aged 85 and above having GA in at least one eye. Bilateral GA leads to severe visual impairment thus posing a significant burden on patients, careers and health providers. The incidence and prevalence of GA varies across different geographic regions, with the highest rates in those of European ancestry. Although heterogeneity in definitions of GA and reporting strategy can explain some of the discrepancies, the data overall are consistent in showing a lower prevalence in other ethnicities such as those of Asian heritage. This is at present unexplained but thought to be due to the existence of protective factors such as differences in eye pigmentation, diet, environmental exposures and genetic variability. This review covers key aspects of the prevalence and incidence of the ocular precursor features of GA (large drusen, pigmentary abnormalities and reticular pseudo-drusen), the late stage of GA and factors that have been known to be associated with modifying risk including systemic, demographic, environment, genetic and ocular. Understanding the global epidemiology scenario is crucial for the prevention of and management of patients with GA.

Biomarkers as Predictive Factors of Anti-VEGF Response

Age-related macular degeneration is the main cause of irreversible vision in developed countries, and intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections are the current gold standard treatment today. Although anti-VEGF treatment results in important improvements in the course of this disease, there is a considerable number of patients not responding to the standardized protocols. The knowledge of how a patient will respond or how frequently retreatment might be required would be vital in planning treatment schedules, saving both resource utilization and financial costs, but today, there is not an ideal biomarker to use as a predictive response to ranibizumab therapy. Whole blood and blood mononuclear cells are the samples most studied; however, few reports are available on other important biofluid samples for studying this disease, such as aqueous humor. Moreover, the great majority of studies carried out to date were focused on the search for SNPs in genes related to AMD risk factors, but miRNAs, proteomic and metabolomics studies have rarely been conducted in anti-VEGF-treated samples. Here, we propose that genomic, proteomic and/or metabolomic markers could be used not alone but in combination with other methods, such as specific clinic characteristics, to identify patients with a poor response to anti-VEGF treatment to establish patient-specific treatment plans.

Choroidal Neovascularization: Mechanisms of Endothelial Dysfunction

Many conditions affecting the heart, brain, and even the eyes have their origins in blood vessel pathology, underscoring the role of vascular regulation. In age-related macular degeneration (AMD), there is excessive growth of abnormal blood vessels in the eye (choroidal neovascularization), eventually leading to vision loss due to detachment of retinal pigmented epithelium. As the advanced stage of this disease involves loss of retinal pigmented epithelium, much less attention has been given to early vascular events such as endothelial dysfunction. Although current gold standard therapy using inhibitors of vascular endothelial growth factor (VEGF) have achieved initial successes, some drawbacks include the lack of long-term restoration of visual acuity, as well as a subset of the patients being refractory to existing treatment, alluding us and others to hypothesize upon VEGF-independent mechanisms. Against this backdrop, we present here a nonexhaustive review on the vascular underpinnings of AMD, implications with genetic and systemic factors, experimental models for studying choroidal neovascularization, and interestingly, on both endothelial-centric pathways and noncell autonomous mechanisms. We hope to shed light on future research directions in improving vascular function in ocular disorders.

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.

Review of the association between retinal microvascular characteristics and eye disease

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

[Multifocal electroretinography for therapeutic effect evaluation of intravitreal injection Lucentis for wet age-related macular degeneration]

OBJECTIVE

To evaluate the changes in retinal functions using multifocal electroretinography (mfERG) following intravitreal injection of Lucentis for treatment of wet age-related macular degeneration.

METHODS

This prospective study was conducted in 14 patients (9 men and 5 women, 14 eyes) with wet age-related macular degeneration receiving treatment with intravitreal injections of ranibizumab (Lucentis) in our hospital between October, 2014 and January, 2016. All the patients received the treatment following a 1+PRN protocol and after the initial injection, the patients were followed up monthly for 6 months to decide if additional injections were needed. The corrected visual acuity and mfERG findings of the patients were assessed before and at l, 3 and 6 months after the initial injection.

RESULTS

At the last follow-up, the patients received injections for a mean of 2.86∓1.58 times. The best corrected visual acuity (BCVA) at 1 month after the initial treatment was not significantly different from that before treatment (P=0.07), but showed significant improvements at 3 and 6 months (P<0.05). In mfERG, the implicit time of the 6 rings showed no significant decrease after the treatment, but the amplitude density of P1 and N1 in rings 1 and 2 improved significantly at 1, 3, and 6 months after the initial injection (P<0.05).

CONCLUSION

Multifocal electroretinography can serve as a useful modality for evaluating visual function changes in patients receiving intravitreal injection of Lucentis for wet age-related macular degeneration.

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.

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

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

Essential hypertension in the pathogenesis of age-related macular degeneration: a review of the current evidence

Age-related macular degeneration (AMD) is one of the main causes of vision loss, especially in the elderly. The involvement of essential hypertension in its pathogenesis has been well covered in the literature since it was first recognized. Hemodynamic abnormalities appear to contribute to AMD, with the renin-angiotensin system playing a significant role. Many studies have demonstrated that high blood pressure is associated with lower choroidal blood flow and disturbed vascular homeostasis in these patients. In addition, AMD is characterized by abnormal neovascularization, to which angiotensin II and growth factors make a large contribution. Most epidemiological studies have found essential hypertension to be a risk factor for AMD. However, although all agree that the strongest predisposing factors are age and smoking, overall there is some inconsistency regarding the exact role of hypertension in its pathogenesis. In particular, there are no data in the literature to support the view that antihypertensive medication and the successful management of hypertension have a positive effect on the clinical outcome of AMD. This reinforces the data indicating that the cause of AMD is multifactorial and suggests that, although essential hypertension probably plays a role, in itself it is unlikely to be a major contributor to the future occurrence of AMD.

Age-related macular degeneration and polypoidal choroidal vasculopathy in Asians

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in elderly people globally. It is estimated that there will be more Asians with AMD than the rest of the world combined by 2050. In Asian populations, polypoidal choroidal vasculopathy (PCV) is a common subtype of exudative AMD, while choroidal neovascularization secondary to AMD (CNV-AMD) is the typical subtype in Western populations. The two subtypes share many common clinical features and risk factors, but also have different epidemiological and clinical characteristics, natural history and treatment outcomes that point to distinct pathophysiological processes. Recent research in the fields of genetics, proteomics and imaging has provided further clarification of differences between PCV and CNV-AMD. Importantly, these differences have manifested as disparity in response to intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) treatment between PCV and CNV-AMD, emphasizing the need for accurate diagnosis of PCV and in distinguishing PCV from CNV-AMD, particularly in Asian patients. Current clinical trials of intravitreal anti-VEGF therapy and photodynamic therapy will provide clearer perspectives of evidence-based management of PCV and may lead to paradigm shifts in therapeutic strategies away from those currently employed in the treatment of CNV-AMD. Further research is needed to clarify the relative contribution of specific pathways in inflammation, complement activation, extracellular matrix dysregulation, lipid metabolism and angiogenesis to the pathogenesis of PCV. Findings from this research, together with improved diagnostic technology and new therapeutics, will facilitate more optimal management of Asian AMD.

Ganglion cell complex thickness in nonexudative age-related macular degeneration

PURPOSE

TO evaluate ganglion cell complex (GCC) thickness with spectral domain optical coherence tomography (SD-OCT) in eyes with nonexudative age-related macular degeneration (NEAMD).

METHODS

Forty-seven eyes of 28 patients with nonexudative age-related macular degeneration (NEAMD) and 54 eyes of 28 age-matched healthy subjects were enrolled. Each subject underwent a complete ophthalmic examination before SD-OCT were obtained. Macular scans were taken with software version 6.0 of the ganglion cell analysis (GCA) algorithm. GCC thickness was evaluated automatically as the average, minimum, temporal superior, superior, nasal superior, nasal inferior, inferior, and temporal-inferior segments by SD-OCT and parameters were compared between groups.

RESULTS

The mean age was 68.7±8.73 years in patient group, and 61.51±5.66 years in control group. There were no significant differences in mean age, gender distribution, intraocular pressure, and sferic equivalent at imaging between the groups (P>0.05). The mean (±SD) GCC thicknesses were as follows; average 71.53±16.53 μm, minumum 62.36±21.51 μm, temporal superior 72.23±14.60 μm, superior 72.76±20.40 μm, nasal superior 72.31±20.13 μm, nasal inferior 69.74±20.51 μm, inferior 69.38±19.03 μm, and temporal-inferior 73.12±15.44 μm in patient group. Corresponding values in control group were 81.46±4.90 μm, 78.66±6.00 μm, 81.51±4.66 μm, 82.94±5.14 μm, 81.79±5.86 μm, 80.94±6.18 μm, 80.14±6.30 μm, and 81.75±5.26 μm, respectively. There were significant differences between two groups in each segments (Mann-Whitney U-test, P<0.05).

CONCLUSION

The average GCC thickness values (in all segments) of NEAMD patients were lower than control group. NEAMD, which is considered as a disease of outer layers of retina, may be accompanied with a decrease of ganglion cell thickness, so inner layers of retina may be affected.