The eye as a model of ageing in translational research--molecular, epigenetic and clinical aspects

Cataract, glaucoma, and diabetic retinopathy are independent risk factors affecting falls in the older adult with eye diseases

OBJECTIVES

Falls are the leading cause of injury-related hospitalization in older adult, presenting a significant public health concern. To examine the specific eye diseases for risk factors of falls in the older adult.

METHODS

A total of 775 older adults admitted to tertiary care hospitals were divided into a fall or non-fall group based on a questionnaire. Logistic regression analysis was used to identify factors associated with falls.

RESULTS

With 208 falls, 775 participants were recruited. The major associated factors of falls were older age (Odds ratios [OR]: 1.05), female (OR: 1.91), cardiovascular diseases (OR: 1.65), more outdoor activities (OR: 2.81), cataract (OR: 1.65), glaucoma (OR: 1.63), diabetic retinopathy (OR: 2.72).

CONCLUSIONS

Our study demonstrates that cataract, glaucoma, and diabetic retinopathy in the older adult with eye diseases are independent risk factors of falls, which may shed light on the prevention of falls in the older adult with eye diseases.

Self-reported cataract surgery and 10-year all-cause and cause-specific mortality: findings from the National Health and Nutrition Examination Survey

PURPOSE

To investigate the association of self-reported cataract surgery with all-cause and cause-specific mortality using a large-scale population-based sample.

METHODS

Data from the 1999-2008 cycles of the National Health and Nutrition Examination Survey were used. A self-reported history of cataract surgery was considered a surrogate for the presence of clinically significant cataract surgery. Mortality data were ascertained from National Death Index records. Hazard ratios (HRs) and 95% confidence intervals (CIs) for survival were estimated using Cox proportional hazards regression models.

RESULTS

A total of 14 918 participants were included in the analysis. During a median follow-up of 10.8 (Interquartile range, IQR, 8.25-13.7) years, 3966 (19.1%) participants died. Participants with self-reported cataract surgery were more likely to die from all causes and specific causes (vascular disease, cancer, accident, Alzheimer's disease, respiratory disease, renal disease and others) compared with those without (all Ps <0.05). The association between self-reported cataract surgery and all-cause mortality remained significant after multiple adjustments (HR=1.13; 95% CI 1.01 to 1.26). For cause-specific mortality, multivariable Cox models showed that self-reported cataract surgery predicted a 36% higher risk of vascular-related mortality (HR=1.36; 95% CI 1.01 to 1.82). The association with other specific causes of mortality did not reach statistical significance after multiple adjustments.

CONCLUSIONS

This study found significant associations of self-reported cataract surgery with all-cause and vascular mortalities. Our findings provide potential insights into the pathogenic pathways underlying cataract.

Are macular drusen in midlife a marker of accelerated biological ageing?

CLINICAL RELEVANCE

Macular drusen are associated with age-related maculopathy but are not an ocular manifestation or biomarker of systemic ageing.

BACKGROUND

Macular drusen are the first sign of age-related maculopathy, an eye disease for which age is the strongest risk factor. The aim of this cohort study was to investigate whether macular drusen in midlife - a sign of the earliest stages of age-related macular degeneration (AMD) - are associated with accelerated biological ageing more generally.

METHODS

Members of the long-running Dunedin Multidisciplinary Health and Development Study (hereafter the Dunedin Study, n = 1037) underwent retinal photography at their most recent assessment at the age of 45 years. Images were graded for the presence of AMD using a simplified scale from the Age-Related Eye Disease Study (AREDS). Accelerated ageing was assessed by (i) a measure of Pace of Ageing defined from a combination of clinical and serum biomarkers obtained at ages 26, 32, 38, and 45 years and (ii) Facial Ageing, defined from photographs obtained at age 38 and 45 years.

RESULTS

Of the 938 participants who participated at the age 45 assessments, 834 had gradable retinal photographs, and of these 165 (19.8%) had macular drusen. There was no significant difference in Pace of Ageing (p = .743) or Facial Ageing (p = .945) among participants with and without macular drusen.

CONCLUSIONS

In this representative general population sample, macular drusen in midlife were not associated with accelerated ageing. Future studies tracking longitudinal changes in drusen number and severity at older ages may reveal whether drusen are a biomarker of accelerated ageing.

Association between dual sensory impairment and risk of mortality: a cohort study from the UK Biobank

BACKGROUND

Dual sensory impairment is affecting over 10% of older adults worldwide. However, the long-term effect of dual sensory impairment (DSI) on the risk of mortality remains controversial. We aim to investigate the impact of single or/and dual sensory impairment on the risk of mortality in a large population-based sample of the adult in the UK with 14-years of follow-up.

METHODS

This population-based prospective cohort study included participants aged 40 and over with complete records of visual and hearing functions from the UK Biobank study. Measurements of visual and hearing functions were performed at baseline examinations between 2006 and 2010, and data on mortality was obtained by 2021. Dual sensory impairment was defined as concurrent visual and hearing impairments. Cox proportional hazards regression models were employed to evaluate the impact of sensory impairment (dual sensory impairment, single visual or hearing impairment) on the hazard of mortality.

RESULTS

Of the 113,563 participants included in this study, the mean age (standard deviation) was 56.8 (8.09) years, and 61,849 (54.5%) were female. At baseline measurements, there were 733 (0.65%) participants with dual sensory impairment, 2,973 (2.62%) participants with single visual impairment, and 13,560 (11.94%) with single hearing impairment. After a follow-up period of 14 years (mean duration of 11 years), 5,992 (5.28%) participants died from all causes. Compared with no sensory impairment, dual sensory impairment was significantly associated with an estimated 44% higher hazard of mortality (hazard ratio: 1.44 [95% confidence interval, 1.11-1.88], p = 0.007) after multiple adjustments.

CONCLUSIONS

Individuals with dual sensory impairment were found to have an independently 44% higher hazard of mortality than those with neither sensory impairment. Timely intervention of sensory impairment and early prevention of its underlying causes should help to reduce the associated risk of mortality.

Visual Impairment, Major Eye Diseases, and Mortality in a Multi-Ethnic Asian Population and a Meta-analysis of Prospective Studies

PURPOSE

Vision impairment (VI) is associated with poor quality of life and increased risk of falls. Few prospective data are available on Asians. This study investigates the longitudinal impact of VI and the major eye diseases on mortality risk in Asians.

DESIGN

Prospective cohort study with meta-analysis.

METHODS

We conducted a multi-ethnic prospective study of adults (40-80 years old) in the Singapore Epidemiology of Eye Diseases Study (baseline: 2004-2011). All-cause mortality was obtained from the National Death Registry until May 2017. VI was defined by best-corrected visual acuity (BCVA) <20/40 in the better eye. Major eye diseases were assessed using standard protocols. We examined associations using multivariate-adjusted Cox proportional hazards regression models. Finally, we conducted a meta-analysis of the associations between VI and mortality.

RESULTS

Of 9,986 participants, 1,210 deaths occurred (12.1%) over a median follow-up of 8.8 years. Compared to participants with normal vision, persons with VI had increased risk of mortality (hazards ratio [HR]: 1.53; 95% confidence interval [CI:] 1.30-1.81) in multivariate models. In ethnicity-specific analyses, this association was significant across Chinese (HR: 1.63; 95% CI: 1.08-2.48); Malays (HR: 1.31; 95% CI: 1.06-1.62); and Indians (HR: 2.25; 95% CI: 1.61-3.15). Cataract, under-corrected refractive errors (URE), and diabetic retinopathy (DR) were significantly associated with mortality (HRs: 1.30, 1.22, and 1.54, respectively). In a meta-analysis of 12 studies including 58,034 persons, VI was associated with 30% increased risk of mortality (HR: 1.3; 95% CI: 1.2-1.5).

CONCLUSIONS

In this multi-ethnic Asian population, VI and preventable eye conditions (cataract, URE, and DR) were associated with mortality, emphasizing the need for early detection and intervention to prevent and treat VI and major eye diseases.

Ocular manifestations and refractive errors among people living with HIV in Pune, India: a cross-sectional study

Objective

We aimed to determine the ocular manifestation and refractive error prevalences among people living with HIV (PLHIV) in Pune, India.

Methods

This cross-sectional study included HIV-infected adults attending a National AIDS Research Institute clinic. Ophthalmologic examination included visual acuity estimation, refraction, orthoptic evaluation, slit lamp and fundus examination, and photography.

Results

In total, 441 HIV-infected individuals were enrolled. The participants' median age was 44 (interquartile range 38–49) years and 227 (51.5%) were men. Refractive errors occurred in 132 (29.9%) individuals. Ocular manifestations were present in 93 (21.1%) participants and the most frequent was cataract in 59 (13.4%) participants. Multivariate logistic regression analysis showed that participants who were illiterate (adjusted odds ratio [AOR] 2.80, 95% confidence interval [CI] 1.47–5.33) and those aged greater than 40 years (AOR 5.59, 95% CI 2.69–11.61) were more likely to have ocular manifestations. The odds of having ocular manifestations were greater in participants with treatment substitution or changes (AOR 2.11, 95% CI 1.16–3.82).

Conclusions

Cataract and refractive errors were prevalent among PLHIV. PLHIV should be encouraged to have regular ophthalmic checkups. Individuals with lower education levels and older age should be counseled regarding eye care and timely reporting of ocular symptoms.

Geographic atrophy severity and mortality in age-related macular degeneration

PURPOSE

To examine the association between geographic atrophy (GA) disease characteristics and mortality risk.

METHODS

We manually delineated color fundus photographs of 209 Age-Related Eye Disease Study (AREDS) participants with GA secondary to age-related macular degeneration to identify total area of atrophy, GA effective radius growth rate, disease laterality, and the presence of foveal center involvement. Associations between GA characteristics and mortality were assessed with Cox proportional hazards models adjusted for health status indicators.

RESULTS

During a median follow-up of 6.8 years, 48 (23.0%) participants with GA died. In adjusted models, accounting for age, sex, and health status, participants with total GA area in the highest quartile had a significantly increased risk of all-cause mortality compared to those with total GA area in the lowest quartile (hazard ratio [HR], 3.42; 95% confidence interval [CI], 1.32-8.86; P = 0.011). GA effective radius growth rate, bilateral disease, and the presence of foveal center involvement were not significantly associated with mortality. In a multivariable model, including health status indicators and all GA characteristics, total area of atrophy in the highest quartile remained significantly associated with mortality (HR, 4.65; 95% CI, 1.29-16.70; P = 0.019).

CONCLUSIONS

More extensive GA, as indicated by a greater total area of atrophy, was associated with an increased risk of all-cause mortality in our cohort. The extent of GA may reflect the extent of underlying disease processes that contribute to greater mortality risk, further suggesting that GA may be part of a systemic rather than purely ocular disease process.

In Vivo Quasi-Elastic Light Scattering Eye Scanner Detects Molecular Aging in Humans

The absence of clinical tools to evaluate individual variation in the pace of aging represents a major impediment to understanding aging and maximizing health throughout life. The human lens is an ideal tissue for quantitative assessment of molecular aging in vivo. Long-lived proteins in lens fiber cells are expressed during fetal life, do not undergo turnover, accumulate molecular alterations throughout life, and are optically accessible in vivo. We used quasi-elastic light scattering (QLS) to measure age-dependent signals in lenses of healthy human subjects. Age-dependent QLS signal changes detected in vivo recapitulated time-dependent changes in hydrodynamic radius, protein polydispersity, and supramolecular order of human lens proteins during long-term incubation (~1 year) and in response to sustained oxidation (~2.5 months) in vitro. Our findings demonstrate that QLS analysis of human lens proteins provides a practical technique for noninvasive assessment of molecular aging in vivo.

Brain Aging in Midlife: The Beaver Dam Offspring Study

OBJECTIVES

Middle age has been identified as a critical time period for health later in life. Identifying factors associated with worse brain function in middle-aged adults may help identify ways to preserve brain function with aging. Our objective was to evaluate factors associated with a novel measure of brain aging in middle-aged and older adults.

DESIGN

Longitudinal cohort study.

SETTING

Beaver Dam Offspring Study (BOSS) baseline (2005-2008), 5-year (2010-2013), and 10-year examinations (2015-2017).

PARTICIPANTS

A total of 2285 adults, 22 to 84 years of age, with complete sensorineural and neurocognitive data at the 5-year examination.

MEASUREMENTS

Principal component analysis (PCA) was performed combining 5-year sensorineural (hearing, vision, olfaction) and cognitive (Trail Making Test A and B, Digit Symbol Substitution Test, Verbal Fluency Test, Auditory Verbal Learning Test) test data. Participants with a standardized PCA score less than -1 were classified as having brain aging. Incident brain aging was defined as a PCA score less than -1 at 10 years among participants who had a PCA score of -1 or higher at 5 years. Logistic regression and Poisson models were used to estimate associations between baseline factors and prevalent or incident brain aging, respectively.

RESULTS

Older age, being male, current smoking, larger waist circumference, not consuming alcohol, cardiovascular disease, and interleukin-6 were associated with greater odds of prevalent brain aging, whereas more education and exercise were associated with decreased odds. In addition to age and sex, less than a college education, higher levels of soluble intercellular adhesion molecule-1, diabetes, depressive symptoms, and history of head injury were associated with an increased 5-year risk of incident brain aging.

CONCLUSION

In the current study, vascular and inflammatory factors were associated with a new brain aging marker in middle-aged and older adults. Many of these factors are modifiable, highlighting the importance of addressing health and lifestyle factors in midlife to potentially preserve function for better brain health later in life. J Am Geriatr Soc 67:1610-1616, 2019.

Glaucoma-associated long-term mortality in a rural cohort from India: the Andhra Pradesh Eye Disease Study

Aim

To evaluate glaucoma-associated mortality in a rural cohort in India.

Methods

The study cohort comprised individuals aged 40 years and above who took part in the Andhra Pradesh Eye Disease Study (APEDS1) during 1996–2000. All participants underwent detailed comprehensive eye examination. Glaucoma was defined using International Society of Geographic and Epidemiologic Ophthalmology criteria. This cohort was followed up after a decade (June 2009 to January 2010; APEDS2). Mortality HR analysis for ocular risk factors was performed using Cox proportional hazards regression after adjusting for sociodemographic, lifestyle and clinical variables.

Results

In APEDS1, 2790 individuals aged more than or equal to 40 years were examined. 47.4% were male. Forty-five participants had primary open angle glaucoma (POAG) and 66 had primary angle closure disease (PACD). Ten years later, 1879 (67.3%) were available, 739 (26.5%) had died and 172 (6.2%) had migrated; whereas 22 of the 45 (48.8%) with POAG and 22 of the 66 (33.3%) with PACD had died. In univariate analysis, a higher mortality was associated with POAG (HR 1.9; 95% CI 1.23 to 2.94), pseudoexfoliation (HR 2.79; 95% CI 2.0 to 3.89), myopia (HR 1.78; 95% CI 1.54 to 2.06) and unit increase in cup:disc ratio (HR 4.49; 95% CI 2.64 to 7.64). In multivariable analysis, only cup:disc ratio remained independently associated with mortality (HR 2.5; 95% CI 1.3 to 5.1). The association remained significant when other ocular parameters were included in the model (HR 2.1; 95% CI 1.03 to 4.2).

Conclusions

This is the first longitudinal study to assess the association of glaucoma and mortality in a rural longitudinal cohort in India. Increased cup:disc ratio could be a potential marker for ageing and would need further validation.

Effect of aging and lifestyle on photoreceptors and retinal pigment epithelium: cross-sectional study in a healthy Danish population

Photoreceptors and their supporting retinal pigment epithelium constitute the key functional parts of the retina. Here, a study was undertaken to show how aging and lifestyle factors affect the photoreceptor layer and the retinal pigment epithelium and Bruch's membrane complex (RPE-BM) in vivo in a healthy Danish population using spectral-domain optical coherence tomography. This was a cross-sectional study of healthy humans aged ≥50 years. All participants were interviewed for medical history and lifestyle factors. Maculae of all participants were scanned using spectral-domain optical coherence tomography. The thickness of the photoreceptor layer and the RPE-BM was measured on one eye from each participant. In 150 eyes of 150 participants, it was found that aging was associated with a decrease in the thickness of the photoreceptor layer (-0.143 μm/year, P = 0.031) and an increase in the thickness of the RPE-BM layer (0.100 μm/year, P = 0.029) at the foveal minimum. Regarding lifestyle factors, alcohol intake or BMI were not associated with any significant trend, but physical inactivity and smoking had effects on the photoreceptor layer (decreased thickness) and the RPE-BM layer (increased thickness) indicating an accelerated aging process of the macula. Taken together, aging affects photoreceptors and the RPE-BM, and these aging trends are accelerated in smokers and the physically inactive.

AGE-RELATED MACULAR DEGENERATION AND THE RISK OF ALL-CAUSE AND CARDIOVASCULAR MORTALITY: A Meta-Analysis of Cohort Studies

PURPOSE

We evaluated the association between age-related macular degeneration (AMD) and the risk of all-cause and cardiovascular mortality by meta-analyses of data from prospective studies.

METHODS

A literature search was performed in PubMed, Web of Science, Embase, Cocharne Library, and China National Knowledge Infrastructure for relevant articles published up to December 2016. We estimated hazard ratios with 95% confidence intervals with fixed-effect models and conducted meta-regression to explore the potential sources of heterogeneity. Small-study effect was estimated by Egger's test and funnel plot.

RESULTS

We identified 13 population-based prospective cohort studies that examined the relationship between AMD and all-cause and cardiovascular mortality. Overall, the hazard ratios (95% confidence intervals) of all-cause mortality and cardiovascular mortality associated with any AMD were 1.15 (1.05-1.27) and 1.05 (95% confidence intervals: 0.87-1.26), respectively. The risk of all-cause mortality and cardiovascular mortality associated with early AMD were 1.08 (1.00-1.18) and 1.05 (0.89-1.24), and the associations with late AMD were 1.23 (1.11-1.36) and 1.28 (1.04-1.57), respectively. No evidence of small-study effect was found.

CONCLUSION

This meta-analysis indicated that AMD, especially late AMD, was associated with increased risk of all-cause mortality and cardiovascular mortality based on comparisons with people who did not have AMD and who were of similar age and sex.

Risk factors for open-angle glaucoma in Nigeria: results from the Nigeria National Blindness and Visual Impairment Survey

BACKGROUND

The glaucoma-specific blindness prevalence in Nigeria (0.7 %, 95 % CI 0.6-0.9 %) among those aged ≥40 years is one of the highest ever reported. This study determined the risk factors for open-angle glaucoma (OAG) in adults examined in the Nigeria National Blindness and Visual Impairment Survey.

METHODS

A nationally representative sample of 13,591 people aged ≥40 years in 305 clusters in Nigeria were examined (response rate 90.4 %) between January 2005 to June 2007. Everyone had logMAR visual acuity measurement, Frequency Doubling Technology (FDT) visual field testing, autorefraction, A-scan biometry and optic disc assessment. Full ocular examination (n = 6397), included Goldmann applanation tonometry. Values for defining glaucoma using International Society of Geographical and Epidemiological Ophthalmology criteria were derived from the study population. Disc images were graded by Moorfields Eye Hospital Reading Centre. Socio-demographic factors (age, gender, ethnicity, literacy and place of residence), ocular parameters (intraocular pressure [IOP], axial length and mean ocular perfusion pressure [MOPP]) and systemic parameters (blood pressure, blood glucose and body mass index [BMI]) were assessed for association with OAG.

RESULTS

Thirteen thousand eighty-one (96 %) of 13,591 participants had vertical cup:disc ratio measured in at least one eye. 682 eyes of 462 participants were classified as OAG, with 12,738 controls. In univariate analyses the following were associated with OAG: increasing age, male gender, Igbo and Yoruba ethnic groups, illiteracy, longer axial length, higher IOP, lower MOPP, greater severity of hypertension and low BMI (underweight). In multivariate analysis, increasing age (odds ratio [OR] 1.04, 95 % CI 1.03-1.05), higher IOP (OR 1.22, 95 % CI 1.18-1.25) and Igbo ethnicity (OR 1.73, 95 % CI 1.18-2.56) were independent risk factors for OAG.

CONCLUSION

Case detection strategies for OAG should be improved for those aged ≥40 years and for ethnic groups most at risk as a public health intervention.

Association of the Fractal Dimension of Retinal Arteries and Veins with Quantitative Brain MRI Measures in HIV-Infected and Uninfected Women

Objective

The fractal dimension of retinal arteries and veins is a measure of the complexity of the vascular tree. We hypothesized that retinal fractal dimension would be associated with brain volume and white matter integrity in HIV-infected women.

Design

Nested case-control within longitudinal cohort study.

Methods

Women were recruited from the Brooklyn site of the Women’s Interagency HIV study (WIHS); 34 HIV-infected and 21 HIV-uninfected women with analyzable MRIs and retinal photographs were included. Fractal dimension was determined using the SIVA software program on skeletonized retinal images. The relationship between predictors (retinal vascular measures) and outcomes (quantitative MRI measures) were analyzed with linear regression models. All models included age, intracranial volume, and both arterial and venous fractal dimension. Some models were adjusted for blood pressure, race/ethnicity, and HIV-infection.

Results

The women were 45.6 ± 7.3 years of age. Higher arterial dimension was associated with larger cortical volumes, but higher venous dimension was associated with smaller cortical volumes. In fully adjusted models, venous dimension was significantly associated with fractional anisotropy (standardized β = -0.41, p = 0.009) and total gray matter volume (β = -0.24, p = 0.03), and arterial dimension with mean diffusivity (β = -0.33,.p = 0.04) and fractional anisotropy (β = 0.34, p = 0.03). HIV-infection was not associated with any retinal or MRI measure.

Conclusions

Higher venous fractal dimension was associated with smaller cortical volumes and lower fractional anisotropy, whereas higher arterial fractal dimension was associated with the opposite patterns. Longitudinal studies are needed to validate this finding.

Perception and Cognition in the Ageing Brain: A Brief Review of the Short- and Long-Term Links between Perceptual and Cognitive Decline

Ageing is associated with declines in both perception and cognition. We review evidence for an interaction between perceptual and cognitive decline in old age. Impoverished perceptual input can increase the cognitive difficulty of tasks, while changes to cognitive strategies can compensate, to some extent, for impaired perception. While there is strong evidence from cross-sectional studies for a link between sensory acuity and cognitive performance in old age, there is not yet compelling evidence from longitudinal studies to suggest that poor perception causes cognitive decline, nor to demonstrate that correcting sensory impairment can improve cognition in the longer term. Most studies have focused on relatively simple measures of sensory (visual and auditory) acuity, but more complex measures of suprathreshold perceptual processes, such as temporal processing, can show a stronger link with cognition. The reviewed evidence underlines the importance of fully accounting for perceptual deficits when investigating cognitive decline in old age.

The Montrachet Study: study design, methodology and analysis of visual acuity and refractive errors in an elderly population

Purpose

To describe the design of the Montrachet Study (Maculopathy Optic Nerve nuTRition neurovAsCular and HEarT diseases) and to report visual acuity and refractive errors in this elderly population.

Methods

Participants were recruited in Dijon (France), from the ongoing population‐based 3C Study. In 2009–2011, 1153 participants from the 3 Cities Study, aged 75 years or more, had an initial eye examination and were scheduled for eye examinations. The eye examination comprised visual acuity, refraction, visual field, ocular surface assessment, photographs and OCT of the macula and the optic disc, measurement of intra‐ocular pressure, central corneal thickness and macular pigment assessment. Information on cardiovascular and neurologic diseases and a large comprehensive database (blood samples, genetic testing, cognitive tests, MRI) were available from the 3C Study.

Results

Presenting visual acuity <20/60 in the better eye was found in 2.3% (95% CI 1.5–3.2) of the participants with no gender differences. Visual impairment increased with age from 1.5% (95% CI 0.3–2.7) for those aged 75–79 years to 5.6% (95% CI 2.9–8.4) for patients 85 years and older (p = 0.0003). Spherical equivalent did not differ between men and women (p = 0.8) and decreased with age whatever the lens status.

Conclusion

Despite the high prevalence of self‐reported eye diseases in this elderly population, visual impairment was low and increased with age. The Montrachet Study may help to better estimate the prevalence of eye diseases in people over 75 years of age and to seek associations with cardiovascular and neurologic diseases and their potential risk factors.

Impact of Visual Impairment and Eye diseases on Mortality: the Singapore Malay Eye Study (SiMES)

We investigated the relationship of visual impairment (VI) and age-related eye diseases with mortality in a prospective, population-based cohort study of 3,280 Malay adults aged 40–80 years between 2004–2006. Participants underwent a full ophthalmic examination and standardized lens and fundus photographic grading. Visual acuity was measured using logMAR chart. VI was defined as presenting (PVA) and best-corrected (BCVA) visual acuity worse than 0.30 logMAR in the better-seeing eye. Participants were linked with mortality records until 2012. During follow-up (median 7.24 years), 398 (12.2%) persons died. In Cox proportional-hazards models adjusting for relevant factors, participants with VI (PVA) had higher all-cause mortality (hazard ratio[HR], 1.57; 95% confidence interval[CI], 1.25–1.96) and cardiovascular (CVD) mortality (HR 1.75; 95% CI, 1.24–2.49) than participants without. Diabetic retinopathy (DR) was associated with increased all-cause (HR 1.70; 95% CI, 1.25–2.36) and CVD mortality (HR 1.57; 95% CI, 1.05–2.43). Retinal vein occlusion (RVO) was associated with increased CVD mortality (HR 3.14; 95% CI, 1.26–7.73). No significant associations were observed between cataract, glaucoma and age-related macular degeneration with mortality. We conclude that persons with VI were more likely to die than persons without. DR and RVO are markers of CVD mortality.

A New Animal Model to Study Endogenous Cardiotonic Steroids and the Progression of Cardiovascular Events in Salt-Sensitive Hypertension

The Dahl salt-sensitive rat is a well-established model to study essential hypertension. We first described a subgroup of these rats based on the unique response pattern in systolic blood pressure during the first weeks of exposure to a high salt diet that included cataract formation. We classified this group as cataract-prone Dahl salt-sensitive rat. We also were able to predict and prevent cataract formation in these rats. Further studies showed an inhibition of lens Na, K-ATPase activity which may be in part responsible for the cataract formation. Other studies in Dahl salt-sensitive rats maintained on a high salt diet have also shown decreased Na, K-ATPase activity in several tissues and increased levels of endogenous circulating Na, K pump inhibitors. For over 20 years, endogenous cardiotonic steroids have been postulated to inhibit Na, K-ATPase in both humans as well as in experimental animal models of hypertension. Recent findings have shown results suggesting that there are several forms of cardiotonic steroids with minor differences in structural functionalities, site of production, and specific pump selectivity. We present original data that supports a role for cardiotonic steroids in disease progression related to increased salt-sensitivity. We found increased levels of free endogenous cardiotonic steroids in those rats that were classified as cataract-prone according to their initial systolic blood pressure response to a high salt intake when compared to non-cataract prone Dahl salt-sensitive rats and their control Dahl salt-resistant rats. The cataract-prone Dahl salt-sensitive rat is an animal model that can help and contribute to open a new door to possibly elucidate the role of endogenous cardiotonic steroids in the pathogenesis and progression of diseases related to salt-sensitive hypertension.

Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53949)

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.

Epigenetics and ocular diseases: from basic biology to clinical study

Epigenetics is an emerging field in ophthalmology and has opened a new avenue for understanding ocular development and ocular diseases related to aging and environment. Epigenetic mechanisms, including DNA methylation, histone modifications, chromatin remodeling, and deployment of non-coding RNAs, result in the heritable silencing of gene expression without any change in DNA sequence. Accumulating evidence suggests a potential link between gene expression, chromatin structure, non-coding RNAs, and cellular differentiation during ocular development. Disruption of the balance of epigenetic networks could become the etiology of several ocular diseases. Here, we summarized the current knowledge about epigenetic regulatory mechanisms in ocular development and diseases.

Cataract, visual impairment and long-term mortality in a rural cohort in India: the Andhra Pradesh Eye Disease Study

BACKGROUND

A large-scale prevalence survey of blindness and visual impairment (The Andhra Pradesh Eye Diseases Study [APEDS1]) was conducted between 1996-2000 on 10,293 individuals of all ages in three rural and one urban clusters in Andhra Pradesh, Southern India. More than a decade later (June 2009-March 2010), APEDS1 participants in rural clusters were traced (termed APEDS2) to determine ocular risk factors for mortality in this longitudinal cohort.

METHODS AND FINDINGS

Mortality hazard ratio (HR) analysis was performed for those aged >30 years at APEDS1, using Cox proportional hazard regression models to identify associations between ocular exposures and risk of mortality. Blindness and visual impairment (VI) were defined using Indian definitions. 799/4,188 (19.1%) participants had died and 308 (7.3%) had migrated. Mortality was higher in males than females (p<0.001). In multivariable analysis, after adjusting for age, gender, diabetes, hypertension, body mass index, smoking and education status the mortality HR was 1.9 (95% CI: 1.5-2.5) for blindness; 1.4 (95% CI: 1.2-1.7) for VI; 1.8 (95% CI: 1.4-2.3) for pure nuclear cataract, 1.5 (95% CI: 1.1-2.1) for pure cortical cataract; 1.96 (95% CI: 1.6-2.4) for mixed cataract, 2.0 (95% CI: 1.4-2.9) for history of cataract surgery, and 1.58 (95% CI: 1.3-1.9) for any cataract. When all these factors were included in the model, the HRs were attenuated, being 1.5 (95% CI: 1.1-2.0) for blindness and 1.2 (95% CI: 0.9-1.5) for VI. For lens type, the HRs were as follows: pure nuclear cataract, 1.6 (95% CI: 1.3-2.1); pure cortical cataract, 1.5 (95% CI: 1.1-2.1); mixed cataract, 1.8 (95% CI: 1.4-2.2), and history of previous cataract surgery, 1.8 (95% CI: 1.3-2.6).

CONCLUSIONS

All types of cataract, history of cataract surgery and VI had an increased risk of mortality that further suggests that these could be potential markers of ageing.

Is HIV a model of accelerated or accentuated aging?

BACKGROUND

Antiretroviral therapy has reduced the incidence of adverse events and early mortality in HIV-infected persons. Despite these benefits, important comorbidities that increase with age (eg, diabetes, cardiovascular disease, cancer, liver disease, and neurocognitive impairment) are more prevalent in HIV-infected persons than in HIV-uninfected persons at every age, and geriatric syndromes such as falls and frailty occur earlier in HIV-infected persons. This raises a critical research question: Does HIV accelerate aging through pathways and mechanisms common to the aging process or is HIV simply an additional risk factor for a wide number of chronic conditions, thus accentuating aging?

METHODS

Extensive literature review.

RESULTS

The purpose of this review is to briefly outline the evidence that age-related clinical syndromes are exacerbated by HIV, examine the ways in which HIV is similar, and dissimilar from natural aging, and assess the validity of HIV as a model of premature aging. Specific biomarkers of aging are limited in HIV-infected hosts and impacted by antiretroviral therapy, and a high rate of modifiable life style confounders (eg, smoking, substance abuse, alcohol) and coinfections (eg, hepatitis) in HIV-infected participants.

CONCLUSIONS

There is a need for validated biomarkers of aging in the context of HIV. Despite these differences, welldesigned studies of HIV-infected participants are likely to provide new opportunities to better understand the mechanisms that lead to aging and age-related diseases.

Ocular parameters of biological ageing in HIV-infected individuals in South Africa: relationship with chronological age and systemic biomarkers of ageing

HIV-infected individuals have an increased risk of age-related morbidity despite antiretroviral treatment (ART). Several anatomic and functional ophthalmological parameters are associated with increasing chronological age. These may, therefore, potentially serve as biomarkers of ageing. We investigated associations between ocular parameters (lens density, retinal vessel calibre, corneal endothelium and retinal nerve fibre layer thickness) and two 'cellular' biomarkers of ageing (leukocyte telomere length and CDKN2A expression) and with frailty in a cross-sectional study of 216 HIV-infected individuals. All ocular parameters, telomere length and frailty were associated with chronological age, whereas CDKN2A expression was not. Retinal venular calibre and lens density were associated with shorter telomere length (p-trend=0.04, and 0.08, respectively), whereas CDKN2A expression and frailty status were not associated with ocular parameters. Longitudinal studies are warranted to assess the integration of retinal vascular calibre and lens density with systemic markers to develop an overall index of biological ageing in HIV infection.

Effect of age on individual retinal layer thickness in normal eyes as measured with spectral-domain optical coherence tomography

PURPOSE

To determine the effect of age on the thickness of individual retinal layers, measured with spectral-domain optical coherence tomography (SD-OCT), in a population of healthy Caucasians.

METHODS

One hundred and twenty subjects with an age ranging between 18 and 81 years were examined with SD-OCT. Mean layer thickness was calculated for seven retinal layers, in the fovea (region 1 of the 9 Early Treatment Diabetic Retinopathy Study [ETDRS] regions); in the pericentral ring (ETDRS regions 2 to 5); and the peripheral ring (ETDRS regions 6 to 9) following automated segmentation using the Iowa Reference Algorithm. In addition, mean peripapillary retinal nerve fiber layer (RNFL) thickness was measured. The partial correlation test was performed on each layer to determine the effect of age on layer thickness, while correcting for spherical equivalent, sex, and Topcon image quality factor as confounders, followed by Bonferroni corrections to adjust for multiple testing.

RESULTS

The thickness of the peripapillary RNFL (R = -0.332; P < 0.001); pericentral ganglion cell layer (R = -0.354, P < 0.001); peripheral inner plexiform layer (R = -0.328, P < 0.001); and foveal outer segment layer (R = -0.381, P < 0.001) decreased significantly with increasing age. Foveal RPE thickness (R = 0.467, P < 0.001) increased significantly with increasing age; other layers showed no significant differences with age.

CONCLUSIONS

Several macular layers and the peripapillary RNFL thickness showed significant changes correlated with age. This should be taken into consideration when analyzing macular layers and the peripapillary RNFL in SD-OCT studies of retinal diseases and glaucoma.

Assessment of candidate ocular biomarkers of ageing in a South African adult population: relationship with chronological age and systemic biomarkers

Certain anatomic and functional parameters of the eye change with increasing chronological age. They may, therefore, serve as potential biomarkers of ageing. We investigated associations between four such ocular parameters (lens density, retinal vessel calibre, corneal endothelial cells and retinal nerve fibre layer thickness) and two 'cellular' biomarkers of ageing (leukocyte telomere length and CDKN2A expression), with frailty (a clinical correlate of biological ageing) in a population of South African adults. All ocular parameters revealed an association with either telomere length or CDKN2A expression. However, lens density was most strongly correlated with age, increased CDKN2A expression, and with frailty (p=0.05 and 0.03, respectively). Narrow retinal arteriolar diameter, associated with increased chronological age, was also associated with increased CDK2NA expression (0.42 vs. 0.31, p=0.02) but not with frailty. Ocular parameters may aid in determining biological age, warranting investigation in longitudinal studies.