Age-Related Macular Degeneration in Chronic Kidney Disease: A Meta-Analysis of Observational Studies

BACKGROUND

Age-related macular degeneration (AMD) is an important cause of blindness in aged people. Chronic kidney disease (CKD) was reported to be associated with a higher risk of AMD. However, supporting evidence was inconsistent between studies. This work intends to examine whether a positive association exists between CKD and AMD by systematic review and meta-analysis.

METHODS

A systematic search of electronic databases (Medline, PubMed, Cochrane and EMBASE) and reference lists on June 2017. The key inclusion criteria were controlled trials that investigated the relationship between AMD and CKD. The outcome measures included risk ratios and/or occurrence rates of AMD in CKD vs. non-CKD population. Data were pooled according to the type of AMD by random effect model.

RESULTS

Twelve observational studies (3 cohorts, 2 case controls, and 7 cross-sectionals) with a total 335,601 participants were included. Eleven studies reported risk ratios and 9 reported occurrence rates. Pooled prevalence for early, advanced, and any AMD were all higher in the CKD population than in the non-CKD population. The pooled multivariate adjusted OR of CKD vs. non-CKD was 1.49 (95% CI 1.11-2.02) for early, 1.55 (95% CI 1.05-2.27) for exudative, 1.58 (95% CI 1.12-2.23) for advanced, and 1.35 (95% CI 1.05-1.73) for any AMD. However, high statistical heterogeneity and methodological diversity existed. Moreover, results were inconsistent between different study designs.

CONCLUSIONS

The overall results support a positive association between CKD and AMD, although some limitations exist. Given the risk that AMD is increased in CKD, regular eye screenings for the CKD population is recommended for an early detection and intervention.

Singlet oxygen quenching- and chain-breaking antioxidant-properties of a quercetin dimer able to prevent age-related macular degeneration

A dimer of quercetin prepared through a Mannich reaction protects pyridinium bisretinoid A2E from photooxidation at 430 nm in aqueous medium at pH 7.4. In the presence of light and O₂, A2E is quickly attacked by ¹O₂ produced in situ (by excited A2E) to give nonaoxirane and other oxygenated compounds which can be involved in diseases of the macula. Peroxyl radicals might have only a marginal role on the photooxidation of A2E. The dimer is actually a potent quencher of ¹O₂ with a rate constant k_Q of 8.5 × 10⁸ M^-1 s^-1 in methanol at room temperature. On the other hand, its antioxidant abilities against ROO^· radicals are quite limited since k_ROO· = 7.3 × 10⁵ M^-1 s^-1 (in buffer solution at pH 7.4), the value being essentially identical to that of quercetin. The quenching of ¹O₂ by the dimer is therefore the main reason for the A2E protection and prevention of age-related macular degeneration.

Dietary flavonoids and the prevalence and 15-y incidence of age-related macular degeneration

Background

The majority of research performed to date has examined the effects of commonly known antioxidants such as vitamins C, E, and A and carotenoids on age-related macular degeneration (AMD) risk and progression. To date, there is limited research on promising phytochemicals with antioxidant and anti-inflammatory properties, including flavonoids.

Objective

In this exploratory study, we aimed to assess the independent associations between dietary intake of total flavonoids and common flavonoid classes with the prevalence and 15-y incidence of AMD.

Design

In this population-based cohort study, 2856 adults aged ≥49 y at baseline and 2037 followed up 15 y later were included in prevalence and incidence analyses, respectively. Dietary intake was assessed by using a semiquantitative food-frequency questionnaire (FFQ). Estimates of the flavonoid content of foods in the FFQ were assessed by using the USDA Flavonoid, Isoflavone, and Proanthocyanidin databases. AMD was assessed from retinal photographs.

Results

In cross-sectional analysis, each 1-SD increase in total overall flavonoid intake was associated with a reduced likelihood of any AMD (multivariable-adjusted OR: 0.76; 95% CI: 0.58, 0.99). Each 1-SD increase in dietary intake of total flavonols and total flavanones was associated with reduced odds of the prevalence of any AMD [multivariable-adjusted OR (95% CI): 0.75 (0.58, 0.97) and 0.77 (0.60, 0.99), respectively]. A marginally significant trend (P = 0.05) was observed between increasing the intake of total flavanone and hesperidin (from the first to the fourth quartile) and reduced likelihood of incident late AMD, after multivariable adjustment. Participants who reported ≥1 serving of oranges/d compared with those who never consumed oranges at baseline had a reduced risk of late AMD 15 y later (multivariable-adjusted OR: 0.39; 95% CI: 0.18, 0.85).

Conclusions

Our findings suggest an independent and protective association between dietary intake of flavonoids and the likelihood of having AMD. Additional prospective cohort studies are needed to validate these findings.

Mechanisms enhancing the protective functions of macular xanthophylls in the retina during oxidative stress

Macular xanthophylls (MXs) are distinguished from other dietary carotenoids by their high membrane solubility and preferential transmembrane orientation. Additionally, these properties enhance the chemical and physical stability of MXs in the eye retina, and maximize their protective activities. The effectiveness of MXs' protection is also enhanced by their selective accumulation in the most vulnerable domains of retinal membranes. The retina is protected by MXs mainly through blue-light filtration, quenching of the excited triplet states of potent photosensitizers, and physical quenching of singlet oxygen. To perform these physical, photo-related actions, the structure of MXs should remain intact. However, the conjugated double-bond structure of MXs makes them highly chemically reactive and susceptible to oxidation. Chemical quenching of singlet oxygen and scavenging of free radicals destroy their intact structure and consume MXs. Consequently, their physical actions, which are critical to the protection of retina, are diminished. Thus, it is timely and important to identify mechanisms whereby the chemical destruction (bleaching) of MXs in retinal membranes can be reduced. It was shown that nitroxide free radicals (spin labels) located in membranes protect MXs against destruction, and their effect is especially pronounced during the light-induced formation of singlet oxygen. That should extend and enhance their positive action in the retina through physical processes. In this review, we will discuss possible applications of this new strategy during ophthalmological procedures, which can cause acute bleaching of MXs and damage the retina through oxidative processes.

Blue-light filtering intraocular lenses (IOLs) for protecting macular health

BACKGROUND

An intraocular lens (IOL) is a synthetic lens that is surgically implanted within the eye following removal of the crystalline lens, during cataract surgery. While all modern IOLs attenuate the transmission of ultra-violet (UV) light, some IOLs, called blue-blocking or blue-light filtering IOLs, also reduce short-wavelength visible light transmission. The rationale for blue-light filtering IOLs derives primarily from cell culture and animal studies, which suggest that short-wavelength visible light can induce retinal photoxicity. Blue-light filtering IOLs have been suggested to impart retinal protection and potentially prevent the development and progression of age-related macular degeneration (AMD). We sought to investigate the evidence relating to these suggested benefits of blue-light filtering IOLs, and to consider any potential adverse effects.

OBJECTIVES

To assess the effects of blue-light filtering IOLs compared with non-blue-light filtering IOLs, with respect to providing protection to macular health and function.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 25 October 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), involving adult participants undergoing cataract extraction, where a blue-light filtering IOL was compared with an equivalent non-blue-light filtering IOL.

DATA COLLECTION AND ANALYSIS

The prespecified primary outcome was the change in distance best-corrected visual acuity (BCVA), as a continuous outcome, between baseline and 12 months of follow-up. Prespecified secondary outcomes included postoperative contrast sensitivity, colour discrimination, macular pigment optical density (MPOD), proportion of eyes with a pathological finding at the macula (including, but not limited to the development or progression of AMD, or both), daytime alertness, reaction time and patient satisfaction. We evaluated findings related to ocular and systemic adverse effects.Two review authors independently screened abstracts and full-text articles, extracted data from eligible RCTs and judged the risk of bias using the Cochrane tool. We reached a consensus on any disagreements by discussion. Where appropriate, we pooled data relating to outcomes and used random-effects or fixed-effect models for the meta-analyses. We summarised the overall certainty of the evidence using GRADE.

MAIN RESULTS

We included 51 RCTs from 17 different countries, although most studies either did not report relevant outcomes, or provided data in a format that could not be extracted. Together, the included studies considered the outcomes of IOL implantation in over 5000 eyes. The number of participants ranged from 13 to 300, and the follow-up period ranged from one month to five years. Only two of the studies had a trial registry record and no studies referred to a published protocol. We did not judge any of the studies to have a low risk of bias in all seven domains. We judged approximately two-thirds of the studies to have a high risk of bias in domains relating to 'blinding of participants and personnel' (performance bias) and 'blinding of outcome assessment' (detection bias).We found with moderate certainty, that distance BCVA with a blue-light filtering IOL, at six to 18 months postoperatively, and measured in logMAR, was not clearly different to distance BCVA with a non-blue-light filtering IOL (mean difference (MD) -0.01 logMAR, 95% confidence interval (CI) -0.03 to 0.02, P = 0.48; 2 studies, 131 eyes).There was very low-certainty evidence relating to any potential inter-intervention difference for the proportion of eyes that developed late-stage AMD at three years of follow-up, or any stage of AMD at one year of follow-up, as data derived from one trial and two trials respectively, and there were no events in either IOL intervention group, for either outcome. There was very low-certainty evidence for the outcome for the proportion of participants who lost 15 or more letters of distance BCVA at six months of follow-up; two trials that considered a total of 63 eyes reported no events, in either IOL intervention group.There were no relevant, combinable data available for outcomes relating to the effect on contrast sensitivity at six months, the proportion of eyes with a measurable loss of colour discrimination from baseline at six months, or the proportion of participants with adverse events with a probable causal link with the study interventions after six months.We were unable to draw reliable conclusions on the relative equivalence or superiority of blue-light filtering IOLs versus non-blue-light filtering IOLs in relation to longer-term effects on macular health. We were also not able to determine with any certainty whether blue-light filtering IOLs have any significant effects on MPOD, contrast sensitivity, colour discrimination, daytime alertness, reaction time or patient satisfaction, relative to non-blue-light filtering IOLs.

AUTHORS' CONCLUSIONS

This systematic review shows with moderate certainty that there is no clinically meaningful difference in short-term BCVA with the two types of IOLs. Further, based upon available data, these findings suggest that there is no clinically meaningful difference in short-term contrast sensitivity with the two interventions, although there was a low level of certainty for this outcome due to a small number of included studies and their inherent risk of bias. Based upon current, best-available research evidence, it is unclear whether blue-light filtering IOLs preserve macular health or alter risks associated with the development and progression of AMD, or both. Further research is required to fully understand the effects of blue-light filtering IOLs for providing protection to macular health and function.

Prophylactic laser in age-related macular degeneration: the past, the present and the future

The presence of drusen in the posterior eye is a hallmark feature of the early stages of age-related macular degeneration and their size is an indicator of risk of progression to vision-threatening forms of the disease. Since the initial observations that laser treatment can resolve drusen, there has been great interest in whether laser treatment can be used to reduce the progression of age-related macular degeneration. In this article, we review the development of lasers for the treatment of those with age-related macular degeneration. We provide an overview of the clinical trial results that demonstrated drusen resolution but that had mixed effects on progression of disease. In addition, we provide a summary of the recent developments in pulsed lasers that are designed to reduce the energy applied to the posterior eye to provide the therapeutic effects of conventional continuous wave lasers while reducing the secondary tissue effects.

Lutein improves cell viability and reduces Alu RNA accumulation in hydrogen peroxide challenged retinal pigment epithelial cells

PURPOSE

Dysfunction of the microRNA (miRNA)-processing enzyme DICER1 and Alu RNA accumulation are linked to the pathogenesis of age-related macular degeneration (AMD). This study determined the optimal dose of lutein (LUT) and zeaxanthin (ZEA) to protect human retinal pigment epithelium (RPE) cells against hydrogen peroxide (H₂O₂). The effect of the optimal dose of LUT and ZEA as DICER1 and Alu RNA modulators in cultured human RPE cells challenged with H₂O₂ was investigated.

MATERIALS AND METHODS

ARPE-19 cells were pre-treated with LUT, ZEA, or both for 24 h before 200 μM H₂O₂ challenge. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. DICER1 and Alu RNA were quantified by western blotting and real-time polymerase chain reaction, respectively.

RESULTS

H₂O₂ increased cell Alu RNA expression and decreased cell viability of ARPE-19, but had no significant impact on the DICER1 protein level. LUT, alone and in combination with ZEA pre-treatment, prior to H₂O₂ challenge significantly improved cell viability of ARPE-19 and reduced the level of Alu RNA compared to the negative control.

CONCLUSIONS

These results support the use of LUT alone, and in combination with ZEA, in AMD prevention and treatment. This study is also the first to report LUT modulating effects on Alu RNA.

Suppression of aberrant choroidal neovascularization through activation of the aryl hydrocarbon receptor

The aryl hydrocarbon receptor (AhR) is a ligand activated transcription factor, initially discovered for its role in regulating xenobiotic metabolism. There is extensive evidence supporting a multi-faceted role for AhR, modulating physiological pathways important in cell health and disease. Recently we demonstrated that the AhR plays a role in the pathogenesis of age-related macular degeneration (AMD), the leading cause of vision loss in the elderly. We found that loss of AhR exacerbates choroidal neovascular (CNV) lesion formation in a murine model. Herein we tested the therapeutic impact of AhR activation on CNV lesion formation and factors associated with aberrant neovascularization. We screened a panel of synthetic drugs and endogenous AhR ligands, assessed their ability to activate AhR in choroidal endothelial cells, and inhibit angiogenesis in vitro. Drugs with an anti-angiogenic profile were then administered to a murine model of CNV. Two compounds, leflunomide and flutamide, significantly inhibited CNV formation concurrent with positive modifying effects on angiogenesis, inflammation, extracellular matrix remodeling, and fibrosis. These results validate the role of the AhR pathway in regulating CNV pathogenesis, identify mechanisms of AhR-based therapies in the eye, and argue in favor of developing AhR as a drug target for the treatment of neovascular AMD.

Prevention of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) compromises quality of life. However, the available therapeutic options are limited. This has led to the identification of modifiable risk factors to prevent the development or alter the natural course and prognosis of AMD. The identification and modification of risk factors has the potential for greater public health impact on reducing morbidity from AMD. Likewise, identifying the imaging clues and genetic clues could serve as a guide to recognizing the propensity for progression to severe and end stages of the disease. Several attempts, both successful and unsuccessful, have been made for interventions that could delay the progression of AMD. Of these, pharmacological interventions have shown promising results. The Age-Related Eye Disease Study 1 and 2 have shown the beneficial role of antioxidants in a selected group of patients.

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

PURPOSE

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

DESIGN

Systematic review and meta-analysis.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration

BACKGROUND

It has been proposed that antioxidants may prevent cellular damage in the retina by reacting with free radicals that are produced in the process of light absorption. Higher dietary levels of antioxidant vitamins and minerals may reduce the risk of progression of age-related macular degeneration (AMD).

OBJECTIVES

The objective of this review was to assess the effects of antioxidant vitamin or mineral supplementation on the progression of AMD in people with AMD.

SEARCH METHODS

We searched CENTRAL (2017, Issue 2), MEDLINE Ovid (1946 to March 2017), Embase Ovid (1947 to March 2017), AMED (1985 to March 2017), OpenGrey (System for Information on Grey Literature in Europe, the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 29 March 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared antioxidant vitamin or mineral supplementation (alone or in combination) to placebo or no intervention, in people with AMD.

DATA COLLECTION AND ANALYSIS

Both review authors independently assessed risk of bias in the included studies and extracted data. One author entered data into RevMan 5; the other author checked the data entry. We graded the certainty of the evidence using GRADE.

MAIN RESULTS

We included 19 studies conducted in USA, Europe, China, and Australia. We judged the trials that contributed data to the review to be at low or unclear risk of bias.Nine studies compared multivitamins with placebo (7 studies) or no treatment (2 studies) in people with early and moderate AMD. The duration of supplementation and follow-up ranged from nine months to six years; one trial followed up beyond two years. Most evidence came from the Age-Related Eye Disease Study (AREDS) in the USA. People taking antioxidant vitamins were less likely to progress to late AMD (odds ratio (OR) 0.72, 95% confidence interval (CI) 0.58 to 0.90; 2445 participants; 3 RCTs; moderate-certainty evidence). In people with very early signs of AMD, who are at low risk of progression, this would mean that there would be approximately 4 fewer cases of progression to late AMD for every 1000 people taking vitamins (1 fewer to 6 fewer cases). In people at high risk of progression (i.e. people with moderate AMD) this would correspond to approximately 8 fewer cases of progression for every 100 people taking vitamins (3 fewer to 13 fewer). In one study of 1206 people, there was a lower risk of progression for both neovascular AMD (OR 0.62, 95% CI 0.47 to 0.82; moderate-certainty evidence) and geographic atrophy (OR 0.75, 95% CI 0.51 to 1.10; moderate-certainty evidence) and a lower risk of losing 3 or more lines of visual acuity (OR 0.77, 95% CI 0.62 to 0.96; 1791 participants; moderate-certainty evidence). Low-certainty evidence from one study of 110 people suggested higher quality of life scores (National Eye Institute Visual Function Questionnaire) in treated compared with the non-treated people after 24 months (mean difference (MD) 12.30, 95% CI 4.24 to 20.36). Six studies compared lutein (with or without zeaxanthin) with placebo. The duration of supplementation and follow-up ranged from six months to five years. Most evidence came from the AREDS2 study in the USA. People taking lutein or zeaxanthin may have similar or slightly reduced risk of progression to late AMD (RR 0.94, 95% CI 0.87 to 1.01; 6891 eyes; low-certainty evidence), neovascular AMD (RR 0.92, 95% CI 0.84 to 1.02; 6891 eyes; low-certainty evidence), and geographic atrophy (RR 0.92, 95% CI 0.80 to 1.05; 6891 eyes; low-certainty evidence). A similar risk of progression to visual loss of 15 or more letters was seen in the lutein and control groups (RR 0.98, 95% CI 0.91 to 1.05; 6656 eyes; low-certainty evidence). Quality of life (measured with Visual Function Questionnaire) was similar between groups in one study of 108 participants (MD 1.48, 95% -5.53 to 8.49, moderate-certainty evidence). One study, conducted in Australia, compared vitamin E with placebo. This study randomised 1204 people to vitamin E or placebo, and followed up for four years. Participants were enrolled from the general population; 19% had AMD. The number of late AMD events was low (N = 7) and the estimate of effect was uncertain (RR 1.36, 95% CI 0.31 to 6.05, very low-certainty evidence). There were no data on neovascular AMD or geographic atrophy.There was no evidence of any effect of treatment on visual loss (RR 1.04, 95% CI 0.74 to 1.47, low-certainty evidence). There were no data on quality of life. Five studies compared zinc with placebo. The duration of supplementation and follow-up ranged from six months to seven years. People taking zinc supplements may be less likely to progress to late AMD (OR 0.83, 95% CI 0.70 to 0.98; 3790 participants; 3 RCTs; low-certainty evidence), neovascular AMD (OR 0.76, 95% CI 0.62 to 0.93; 2442 participants; 1 RCT; moderate-certainty evidence), geographic atrophy (OR 0.84, 95% CI 0.64 to 1.10; 2442 participants; 1 RCT; moderate-certainty evidence), or visual loss (OR 0.87, 95% CI 0.75 to 1.00; 3791 participants; 2 RCTs; moderate-certainty evidence). There were no data reported on quality of life.Very low-certainty evidence was available on adverse effects because the included studies were underpowered and adverse effects inconsistently reported.

AUTHORS' CONCLUSIONS

People with AMD may experience some delay in progression of the disease with multivitamin antioxidant vitamin and mineral supplementation. This finding was largely drawn from one large trial, conducted in a relatively well-nourished American population. We do not know the generalisability of these findings to other populations. Although generally regarded as safe, vitamin supplements may have harmful effects. A systematic review of the evidence on harms of vitamin supplements is needed. Supplements containing lutein and zeaxanthin are heavily marketed for people with age-related macular degeneration but our review shows they may have little or no effect on the progression of AMD.

Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration

BACKGROUND

There is inconclusive evidence from observational studies to suggest that people who eat a diet rich in antioxidant vitamins (carotenoids, vitamins C, and E) or minerals (selenium and zinc) may be less likely to develop age-related macular degeneration (AMD).

OBJECTIVES

To determine whether or not taking antioxidant vitamin or mineral supplements, or both, prevent the development of AMD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 2), MEDLINE Ovid (1946 to 29 March 2017), Embase Ovid (1947 to 29 March 2017), AMED (Allied and Complementary Medicine Database) (1985 to 29 March 2017), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/); searched 29 March 2017, the ISRCTN registry (www.isrctn.com/editAdvancedSearch); searched 29 March 2017, ClinicalTrials.gov (www.clinicaltrials.gov); searched 29 March 2017 and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 29 March 2017. We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing an antioxidant vitamin or mineral supplement (alone or in combination) to control.

DATA COLLECTION AND ANALYSIS

Both review authors independently assessed risk of bias in the included studies and extracted data. One author entered data into RevMan 5; the other author checked the data entry. We pooled data using a fixed-effect model. We graded the certainty of the evidence using GRADE.

MAIN RESULTS

We included a total of five RCTs in this review with data available for 76,756 people. The trials were conducted in Australia, Finland, and the USA, and investigated vitamin C, vitamin E, beta-carotene, and multivitamin supplements. All trials were judged to be at low risk of bias.Four studies reported the comparison of vitamin E with placebo. Average treatment and follow-up duration ranged from 4 to 10 years. Data were available for a total of 55,614 participants. There was evidence that vitamin E supplements do not prevent the development of any AMD (risk ratio (RR) 0.97, 95% confidence interval (CI) 0.90 to 1.06; high-certainty evidence), and may slightly increase the risk of late AMD (RR 1.22, 95% CI 0.89 to 1.67; moderate-certainty evidence) compared with placebo. Only one study (941 participants) reported data separately for neovascular AMD and geographic atrophy. There were 10 cases of neovascular AMD (RR 3.62, 95% CI 0.77 to 16.95; very low-certainty evidence), and four cases of geographic atrophy (RR 2.71, 95% CI 0.28 to 26.0; very low-certainty evidence). Two trials reported similar numbers of adverse events in the vitamin E and placebo groups. Another trial reported excess of haemorrhagic strokes in the vitamin E group (39 versus 23 events, hazard ratio 1.74, 95% CI 1.04 to 2.91, low-certainty evidence).Two studies reported the comparison of beta-carotene with placebo. These studies took place in Finland and the USA. Both trials enrolled men only. Average treatment and follow-up duration was 6 years and 12 years. Data were available for a total of 22,083 participants. There was evidence that beta-carotene supplements did not prevent any AMD (RR 1.00, 95% CI 0.88 to 1.14; high-certainty evidence) nor have an important effect on late AMD (RR 0.90, 95% CI 0.65 to 1.24; moderate-certainty evidence). Only one study (941 participants) reported data separately for neovascular AMD and geographic atrophy. There were 10 cases of neovascular AMD (RR 0.61, 95% CI 0.17 to 2.15; very low-certainty evidence) and 4 cases of geographic atrophy (RR 0.31 95% CI 0.03 to 2.93; very low-certainty evidence). Beta-carotene was associated with increased risk of lung cancer in people who smoked.One study reported the comparison of vitamin C with placebo, and multivitamin (Centrum Silver) versus placebo. This was a study in men in the USA with average treatment duration and follow-up of 8 years for vitamin C and 11 years for multivitamin. Data were available for a total of 14,236 participants. AMD was assessed by self-report followed by medical record review. There was evidence that vitamin C supplementation did not prevent any AMD (RR 0.96, 95% CI 0.79 to 1.18; high-certainty evidence) or late AMD (RR 0.94, 0.61 to 1.46; moderate-certainty evidence). There was a slight increased risk of any AMD (RR 1.21, 95% CI 1.02 to 1.43; moderate-certainty evidence) and late AMD (RR 1.22, 95% CI 0.88 to 1.69; moderate-certainty evidence) in the multivitamin group. Neovascular AMD and geographic atrophy were not reported separately. Adverse effects were not reported but there was possible increased risk of skin rashes in the multivitamin group.Adverse effects were not consistently reported in these eye studies, but there is evidence from other large studies that beta-carotene increases the risk of lung cancer in people who smoke or who have been exposed to asbestos.None of the studies reported quality of life or resource use and costs.

AUTHORS' CONCLUSIONS

Taking vitamin E or beta-carotene supplements will not prevent or delay the onset of AMD. The same probably applies to vitamin C and the multivitamin (Centrum Silver) investigated in the one trial reported to date. There is no evidence with respect to other antioxidant supplements, such as lutein and zeaxanthin. Although generally regarded as safe, vitamin supplements may have harmful effects, and clear evidence of benefit is needed before they can be recommended. People with AMD should see the related Cochrane Review on antioxidant vitamin and mineral supplements for slowing the progression of AMD, written by the same review team.

Nutrition, Genes, and Age-Related Macular Degeneration: What Have We Learned from the Trials?

The Age-Related Eye Disease Study (AREDS) and AREDS2 provided evidence for treating persons with age-related macular degeneration (AMD) with antioxidant vitamins and minerals to reduce the risk of development of late AMD. The AREDS2 data suggest that the beta-carotene in the original AREDS supplements be replaced by lutein and zeaxanthin, providing a safer drug for those who are smokers or former smokers. Even though consuming fish reduced the risk of AMD in observational studies, the AREDS2 results showed that omega-3 long-chain polyunsaturated fatty acids (docosahexaenoic acid/eicosapentaenoic acid) had no beneficial effect on AMD. Despite the major progress in the discovery of gene variants associated with AMD, the use of genetic testing to predict disease has not been clinically useful. The use of genetic testing prior to AMD therapies such as administering AREDS supplements is not recommended by the American Academy of Ophthalmology and other organizations.

The Pharmacological Effects of Lutein and Zeaxanthin on Visual Disorders and Cognition Diseases

Lutein (L) and zeaxanthin (Z) are dietary carotenoids derived from dark green leafy vegetables, orange and yellow fruits that form the macular pigment of the human eyes. It was hypothesized that they protect against visual disorders and cognition diseases, such as age-related macular degeneration (AMD), age-related cataract (ARC), cognition diseases, ischemic/hypoxia induced retinopathy, light damage of the retina, retinitis pigmentosa, retinal detachment, uveitis and diabetic retinopathy. The mechanism by which they are involved in the prevention of eye diseases may be due their physical blue light filtration properties and local antioxidant activity. In addition to their protective roles against light-induced oxidative damage, there are increasing evidences that L and Z may also improve normal ocular function by enhancing contrast sensitivity and by reducing glare disability. Surveys about L and Z supplementation have indicated that moderate intakes of L and Z are associated with decreased AMD risk and less visual impairment. Furthermore, this review discusses the appropriate consumption quantities, the consumption safety of L, side effects and future research directions.

Lutein and Zeaxanthin-Food Sources, Bioavailability and Dietary Variety in Age-Related Macular Degeneration Protection

Lutein and zeaxanthin (L/Z) are the predominant carotenoids which accumulate in the retina of the eye. The impact of L/Z intake on the risk and progression of age-related macular degeneration (AMD), a leading cause of blindness in the developed world, has been investigated in cohort studies and clinical trials. The aims of this review were to critically examine the literature and evaluate the current evidence relating to L/Z intake and AMD, and describe important food sources and factors that increase the bioavailability of L/Z, to inform dietary models. Cohort studies generally assessed L/Z from dietary sources, while clinical trials focused on providing L/Z as a supplement. Important considerations to take into account in relation to dietary L/Z include: nutrient-rich sources of L/Z, cooking methods, diet variety and the use of healthy fats. Dietary models include examples of how suggested effective levels of L/Z can be achieved through diet alone, with values of 5 mg and 10 mg per day described. These diet models depict a variety of food sources, not only from dark green leafy vegetables, but also include pistachio nuts and other highly bioavailable sources of L/Z such as eggs. This review and the diet models outlined provide information about the importance of diet variety among people at high risk of AMD or with early signs and symptoms of AMD.

[Nutritional prevention of age-related macular degeneration]

Nutritional prevention of age-related macular degeneration. Age-related macular degeneration is the leading cause of blindness in industrialized countries. Nowadays, the treatments of this chronic pathology do not make it possible to avoid the visual loss in the long term. Nutritional prevention thus remains an indispensable means to delay the consequences of this pathology. This article reports the various nutrients that have proved their worth in the prevention of AMD.

Fish Consumption and Age-Related Macular Degeneration Incidence: A Meta-Analysis and Systematic Review of Prospective Cohort Studies

The association between fish consumption and risk of age-related macular degeneration (AMD) is still unclear. The aim of the current meta-analysis and systematic review was to quantitatively evaluate findings from observational studies on fish consumption and the risk of AMD. Relevant studies were identified by searching electronic databases (Medline and EMBASE) and reviewing the reference lists of relevant articles up to August, 2016. Prospective cohort studies that reported relative risks (RRs) and 95% confidence intervals (CIs) for the link between fish consumption and risk of AMD were included. A total of 4202 cases with 128,988 individuals from eight cohort studies were identified in the current meta-analysis. The meta-analyzed RR was 0.76 (95% CI, 0.65-0.90) when any AMD was considered. Subgroup analyses by AMD stages showed that fish consumption would reduce the risk of both early (RR, 0.83; 95% CI, 0.72-0.96) and late (RR; 0.76; 95% CI, 0.60-0.97) AMD. When stratified by the follow-up duration, fish consumption was a protective factor of AMD in both over 10 years (n = 5; RR, 0.81; 95% CI, 0.67-0.97) and less than 10 years (n = 3; RR, 0.70; 95% CI, 0.51 to 0.97) follow-up duration. Stratified analyses by fish type demonstrated that dark meat fish (RR, 0.68, 95% CI, 0.46-0.99), especially tuna fish (RR, 0.58; 95% CI, 95% CI, 0.47-0.71) intake was associated with reduced AMD risk. Evidence of a linear association between dose of fish consumption and risk of AMD was demonstrated. The results of this meta-analysis demonstrated that fish consumption can reduce AMD risk. Advanced, well-designed, randomized clinical trials are required in order to validate the conclusions in this study.

Statins for age-related macular degeneration

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Perspective: A Critical Look at the Ancillary Age-Related Eye Disease Study 2: Nutrition and Cognitive Function Results in Older Individuals with Age-Related Macular Degeneration

A large body of literature suggests that the dietary carotenoids lutein and zeaxanthin and long-chain polyunsaturated fatty acids such as docosahexaenoic acid are related to improved cognitive function across the life span. A recent report by the Age-Related Eye Disease Study (AREDS) group appears to contradict the general findings of others in the field. In this review, we look critically at the methods, study designs, and analysis techniques used in the larger body of literature and compare them with the recent AREDS reports.

Therapeutic Approaches to Histone Reprogramming in Retinal Degeneration

Recent data have revealed epigenetic derangements and subsequent chromatin remodeling as a potent biologic switch for chronic inflammation and cell survival which are important therapeutic targets in the pathogenesis of several retinal degenerations. Histone deacetylases (HDACs) are a major component of this system and serve as a unique control of the chromatin remodeling process. With a multitude of targeted HDAC inhibitors now available, their use in both basic science and clinical studies has widened substantially. In the field of ocular biology, there are data to suggest that HDAC inhibition may suppress neovascularization and may be a possible treatment for retinitis pigmentosa and dry age-related macular degeneration (AMD). However, the effects of these inhibitors on cell survival and chemokine expression in the chorioretinal tissues remain very unclear. Here, we review the multifaceted biology of HDAC activity and pharmacologic inhibition while offering further insight into the importance of this epigenetic pathway in retinal degenerations. Our laboratory investigations aim to open translational avenues to advance dry AMD therapeutics while exploring the role of acetylation on inflammatory gene expression in the aging and degenerating retina.

Can Vitamin A be Improved to Prevent Blindness due to Age-Related Macular Degeneration, Stargardt Disease and Other Retinal Dystrophies?

We discuss how an imperfect visual cycle results in the formation of vitamin A dimers, thought to be involved in the pathogenesis of various retinal diseases, and summarize how slowing vitamin A dimerization has been a therapeutic target of interest to prevent blindness. To elucidate the molecular mechanism of vitamin A dimerization, an alternative form of vitamin A, one that forms dimers more slowly yet maneuvers effortlessly through the visual cycle, was developed. Such a vitamin A, reinforced with deuterium (C20-D3-vitamin A), can be used as a non-disruptive tool to understand the contribution of vitamin A dimers to vision loss. Eventually, C20-D3-vitamin A could become a disease-modifying therapy to slow or stop vision loss associated with dry age-related macular degeneration (AMD), Stargardt disease and retinal diseases marked by such vitamin A dimers. Human clinical trials of C20-D3-vitamin A (ALK-001) are underway.

Joint Associations of Diet, Lifestyle, and Genes with Age-Related Macular Degeneration

PURPOSE

Unhealthy lifestyles have been associated with increased odds for age-related macular degeneration (AMD). Whether this association is modified by genetic risk for AMD is unknown and was investigated.

DESIGN

Interactions between healthy lifestyles AMD risk genotypes were studied in relation to the prevalence of AMD, assessed 6 years later.

PARTICIPANTS

Women 50 to 79 years of age in the Carotenoids in Age-Related Eye Disease Study with exposure and AMD data (n=1663).

METHODS

Healthy lifestyle scores (0-6 points) were assigned based on Healthy Eating Index scores, physical activity (metabolic equivalent of task hours/week), and smoking pack years assessed in 1994 and 1998. Genetic risk was based on Y402H in complement factor H (CFH) and A69S in age-related maculopathy susceptibility locus 2 (ARMS2). Additive and multiplicative interactions in odds ratios were assessed using the synergy index and a multiplicative interaction term, respectively.

MAIN OUTCOME MEASURES

AMD presence and severity were assessed from grading of stereoscopic fundus photographs taken in 2001-2004. AMD was present in 337 women, 91% of whom had early AMD.

RESULTS

The odds of AMD were 3.3 times greater (95% confidence interval [CI], 1.8-6.1) in women with both low healthy lifestyle score (0-2) and high-risk CFH genotype (CC), relative to those who had low genetic risk (TT) and high healthy lifestyle scores (4-6). There were no significant additive (synergy index [SI], 1.08; 95% CI, 0.70-1.67) or multiplicative (Pinteraction=0.94) interactions in the full sample. However, when limiting the sample to women with stable diets before AMD assessment (n=728) the odds for AMD associated with low healthy lifestyle scores and high-risk CFH genotype were strengthened (odds ratio, 4.6; 95% CI, 1.8-11.6) and the synergy index was significant (SI, 1.34; 95% CI, 1.05-1.70). Adjusting for dietary lutein and zeaxanthin attenuated, and therefore partially explained, the joint association. There were no significant additive or multiplicative interactions for ARMS2 and lifestyle score.

CONCLUSIONS

Having unhealthy lifestyles and 2 CFH risk alleles increased AMD risk (primarily in the early stages), in an or additive or greater (synergistic) manner. However, unhealthy lifestyles increased AMD risk regardless of AMD risk genotype.

Laser treatment of drusen to prevent progression to advanced age-related macular degeneration

BACKGROUND

Drusen are amorphous yellowish deposits beneath the sensory retina. People with drusen, particularly large drusen, are at higher risk of developing age-related macular degeneration (AMD). The most common complication in AMD is choroidal neovascularisation (CNV), the growth of new blood vessels in the centre of the macula. The risk of CNV is higher among people who are already affected by CNV in one eye.It has been observed clinically that laser photocoagulation of drusen leads to their disappearance and may prevent the occurrence of advanced disease (CNV or geographic atrophy) associated with visual loss.

OBJECTIVES

To examine the effectiveness and adverse effects of laser photocoagulation of drusen in AMD.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2015, Issue 7), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to August 2015), EMBASE (January 1980 to August 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to August 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 3 August 2015.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of laser treatment of drusen in AMD in which laser treatment had been compared with no intervention or sham treatment. Two types of trials were included. Some trials studied one eye of each participant (unilateral studies); other studies recruited participants with bilateral drusen and randomised one eye to photocoagulation or control and the fellow eye to the other group.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and extracted data. We pooled data from unilateral and bilateral studies using a random-effects model. For the bilateral studies, we estimated the within-person correlation coefficient from one study and assumed it was valid for the others.

MAIN RESULTS

The update of this review found two additional studies, totaling 11 studies that randomised 2159 participants (3580 eyes) and followed them up to two years, of which six studies (1454 participants) included people with one eye randomised to treatment and one to control. Studies were conducted in Australia, Europe and North America.Overall, the risk of bias in the included studies was low, particularly for the larger studies and for the primary outcome development of CNV. Photocoagulation did not reduce the development of CNV at two years' follow-up (odds ratio (OR) 1.07, 95% confidence interval (CI) 0.79 to 1.46, 11 studies, 2159 participants (3580 eyes), high quality evidence). This estimate means that, given an overall occurrence of CNV of 8.3% in the control group, we estimated an absolute risk reduction by no more than 1.4% in the laser group, according to the lower CI limit. Only two studies investigated the effect on the development of geographic atrophy and could not show a difference, but estimates were imprecise (OR 1.30, 95% CI 0.38 to 4.51, two studies, 148 participants (148 eyes), low quality evidence).Among secondary outcomes, photocoagulation led to drusen reduction (OR 9.16, 95% CI 6.28 to 13.4, three studies, 570 participants (944 eyes), high quality evidence) but was not shown to limit loss of 3 or more lines of visual acuity (OR 0.99, 95% CI 0.81 to 1.22, nine studies, 2002 participants (2386 eyes), moderate quality evidence).In a subgroup analysis, no difference could be shown for conventional visible (eight studies) versus subthreshold invisible (four studies) photocoagulation for the primary outcomes (P value = 0.29). The effect in the subthreshold group did not suggest a relevant benefit (OR 1.27, 95% CI 0.82 to 1.98). No study used micropulse subthreshold photocoagulation.No other adverse effects (apart from development of CNV, geographic atrophy or visual loss) were reported.

AUTHORS' CONCLUSIONS

The trials included in this review confirm the clinical observation that laser photocoagulation of drusen leads to their disappearance. However, treatment does not result in a reduction in the risk of developing CNV, and was not shown to limit the occurrence of geographic atrophy or visual acuity loss.Ongoing studies are being conducted to assess whether the use of extremely short laser pulses (i.e. nanosecond laser treatment) cannot only lead to drusen regression but also prevent neovascular AMD.

[Physical activity benefits patients with age-related macular degeneration]

We have reviewed studies investigating the effect of physical activity on prevention of early age-related macular degeneration (AMD), progression to late AMD, and risk modulation of morbidity and mortality in patients with AMD. Regular physical activity may lower risk of developing early AMD and progression of early AMD to late AMD at a level comparable with smoking cessation or dietary supplements. Studies suggest that AMD itself is associated with physical inactivity which can result in higher morbidity levels. Patients with AMD may benefit from physical activity counselling at all stages of the disease.

The effect of blue-blocking intraocular lenses on circadian biological rhythm: protocol for a randomised controlled trial (CLOCK-IOL colour study)

INTRODUCTION

Blue light information plays an important role in synchronising internal biological rhythm within the external environment. Circadian misalignment is associated with the increased risk of sleep disturbance, obesity, diabetes mellitus, depression, ischaemic heart disease, stroke and cancer. Meanwhile, blue light causes photochemical damage to the retina, and may be associated with age-related macular degeneration (AMD). At present, clear intraocular lenses (IOLs) and blue-blocking IOLs are both widely used for cataract surgery; there is currently a lack of randomised controlled trials to determine whether clear or blue-blocking IOLs should be used.

METHODS AND ANALYSIS

This randomised controlled trial will recruit 1000 cataract patients and randomly allocate them to receive clear IOLs or blue-blocking IOLs in a ratio of 1:1. The primary outcomes are mortality and the incidence of cardiovascular disease, cancer and AMD. Secondary outcomes are fasting plasma glucose, triglycerides, cholesterol, glycated haemoglobin, sleep quality, daytime sleepiness depressive symptoms, light sensitivity, the circadian rhythm of physical activity, wrist skin temperature and urinary melatonin metabolite. Primary outcomes will be followed until 20 years after surgery, and secondary outcomes will be assessed at baseline and 1 year after surgery.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Institutional Review Board of Nara Medical University (No. 13-032). The findings of this study will be communicated to healthcare professionals, participants and the public through peer-reviewed publications, scientific conferences and the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) home page.

TRIAL REGISTRATION NUMBER

UMIN000014680.