Unexpected potential protective associations between outdoor air pollution and cataracts

A novel cataract-related mutation R10P in γA-crystallin increases susceptibility to thermal shock and ultraviolet radiation of γA-crystallin

Congenital cataract is one of the most common causes of childhood blindness, typically resulting from genetic mutations. Over a hundred gene mutations associated with congenital cataract have been identified, with approximately half occurring in the Crystallin genes. In this study, we identified a novel γA-crystallin pathogenic mutation (c. 29G > C, p. Arg10Pro (R10P)), from a four-generation Chinese family with congenital cataract, and investigated its potential molecular mechanisms underlying congenital cataracts. We compared the protein structure and stability of purified the wild type (WT) and R10P under physiological conditions and environmental stresses (UV irradiation, pH imbalance, heat shock, and chemical denaturation) using spectroscopic experiments, SEC analysis, and the UNcle protein analysis system. The results demonstrate that γA-R10P has no significant impact on the structure of γA-crystallin on normal condition. However, it is more sensitive to UV irradiation at high concentrations and prone to aggregation at high temperatures. Therefore, our study reveals the crucial role of the conserved site mutation R10P in maintaining protein structure and stability, providing new insights into the mechanisms of cataract formation.

Association of exposure to ultraviolet radiation and warm-season ozone air pollution with incident age-related macular degeneration: A nationwide cohort study in China

BACKGROUND

As the leading cause of blindness, age-related macular degeneration (AMD) performs an adverse impact on human health and disability. AMD have been reported to be associated with environmental factors; however, the association between ultraviolet (UV) radiation, warm-season ambient ozone pollution, and incident AMD remains unclear.

METHODS

In this study, 19,707 participants without AMD at baseline were included from a nationwide longitudinal cohort in China. UV radiation and warm-season ozone exposure were evaluated through satellite-based models. Incident AMD was diagnosed via ophthalmological fundus images. Cox proportional hazard regression models were employed to explore the association of UV radiation and warm-season ozone with incident AMD, and the hazard ratios (HRs) and 95 % confidence intervals (CIs) were reported.

RESULTS

During 312,935 person-month of follow-up, 3774 participants developed to AMD. High exposure to both UV radiation and warm-season ozone was associated with increasing risk of incident AMD, with HRs and 95 % CIs of 1.32 (1.23, 1.41) and 1.20 (1.11, 1.29) in two-exposure models, respectively. Moreover, negative interaction between UV radiation and warm-season ozone was identified, and it was found that exposure to high UV radiation and low ozone presented the highest hazard for AMD. Subgroup analyses showed that the UV-AMD association was stronger in southern China, while the ozone-AMD association was greater in northern China and rural areas.

CONCLUSION

Our study provides the first epidemiological evidence that both UV radiation and warm-season ozone would elevate the risk of incident AMD, and the hazard of higher UV radiation may be attenuated by exposure to ozone. Strategies for decreasing AMD burden should jointly consider environmental exposures and geographic locations.

The impact of air pollution and climate change on eye health: a global review

Climate change has important implications on human health, affecting almost every system in the body. Multiple studies have raised the possibility of climate change impacting eye health. In this review, we aimed to summarize current literature on the impact of air pollution and climate change on eye health. We performed a search in four different databases, including Medline, Scopus, Cochrane, and Web of Sciences databases. The search strategy combined terms regarding eye health and environmental/climate changes. The outcome of interest included all eye conditions. The search yielded 2,051 unique articles. After applying inclusion and exclusion criteria, 61 articles were included in this systematic review with data covering 2,620,030 participants. Most studies originated from China, India, South Korea, and USA. Climate change adversely affected different eye conditions, with ocular surface diseases (e.g., conjunctivitis and dry eye) being most affected. Moreover, higher particulate matter (PM) was the most widely assessed pollutant and was adversely associated with the majority of eye conditions, increasing the burden on patients and healthcare providers. We found a low frequency of publications related to the delivery of eye care and its impact on climate change in countries with high air pollution and climate change burden.

Association of nuclear cataract prevalence with UV radiation and heat load in lens of older people -five city study

Epidemiological studies have reported that the frequency of nuclear cataracts (NUCs) is high among the elderly and in tropical countries. Ultraviolet (UV) irradiation and lens temperature are considered as key physical contributors, although their precise quantification is difficult. The aim of this study is to investigate the association of NUC prevalence with UV irradiation and heat load. First, we assessed the lens temperature using thermodynamic modeling considering the thermophysiological response. We then conducted a multivariate linear regression analysis for the epidemiological analysis of NUC prevalence across five cities. A strong correlation was observed between NUC prevalence and the combined effects of UV irradiation and cumulative equivalent minutes at 43 °C (CEM43°C) derived from the computed lens temperature (adjusted R2 = 0.933, p < 0.0001). Heat load significantly contributed to the prevalence at 52%, surpassing the contributions of UV irradiation (31%) and the decline in DNA repair capacity in the lens (17%). These results suggested that both UV radiation and heat load are associated with NUC, with heat load contributing more. Our findings provided important implications for future interventions, particularly in the context of global warming.

The Correlation of Global Burden of Vision Impairment and Ambient Atmospheric Fine Particulate Matter

Purpose

To assess the correlation between the worldwide burden of vision impairment (VI) and fine particulate matter (PM) 2.5.

Methods

In this retrospective cross-sectional study, global and national prevalence and disability-adjusted lost year (DALY) numbers and rates of total VI, glaucoma, cataract, and age-related macular degeneration (AMD) were obtained from the Global Burden of Disease database. The global and national levels of PM2.5 levels were also extracted. The main outcome measures were the correlation of PM2.5 levels with total VI and three ocular diseases in different age, sex, and socioeconomic subgroups.

Results

In 2019, the worldwide prevalence of total VI and exposure level of PM2.5 was 9.6% (95% uncertainty interval: 8.0-11.3) and 42.5 μg/m3, respectively. The national age-standardized prevalence rates of total VI (r p = 0.52, P < 0.001), glaucoma (r p = 0.65, P < 0.001), AMD (r p = 0.67, P < 0.001), and cataract (r p = 0.44, P < 0.001) have a positive correlation with PM2.5 levels. In addition, the national age-standardized DALY rates of total VI (r p = 0.62, P < 0.001), glaucoma (r p = 0.62, P < 0.001), AMD (r p = 0.54, P < 0.001), and cataract (r p = 0.45, P < 0.001) significantly correlated with PM2.5 levels. The correlations remained significant in different age, sex, and sociodemographic subgroups.

Conclusion

National prevalence rates of VI and three major ocular diseases correlate significantly with PM2.5 exposure levels, worldwide.

Long-Term Exposure to Ambient PM2.5 and Age-Related Cataracts among Chinese Middle-Aged and Older Adults: Evidence from Two National Cohort Studies

Cataract is one key cause of visual disability and blindness. Ambient particulate matter is more likely to increase cataract risk due to eye continuous exposure to the environment. However, less is known about whether long-term exposure to particulate matter 2.5 (PM2.5) is related to age-related cataracts. We conducted a population-based study among 22,298 adults from two multicenter cohort studies [China Family Panel Studies (CFPS) and Chinese Longitudinal Healthy Longevity Survey (CLHLS)]. The associations between PM2.5 and age-related cataracts were analyzed by Cox proportional hazard regression models, which were also stratified according to demographic characteristics. The restricted cubic spline (RCS) model was used to explore the dose-response relationships between PM2.5 and age-related cataracts. The population attributable fraction (PAF) was calculated to assess the burden of age-related cataracts that can be attributed to PM2.5. In the final analysis, 1897 participants reported age-related cataracts during follow-up. Long-term exposure to PM2.5 was associated with age-related cataracts, with HRs of 1.165 (1.130, 1.201), 1.138 (1.103, 1.173), and 1.091 (1.057, 1.126) for per 10 μg/m3 increase at one-, two-, and three-year before the end of follow-up, respectively. Furthermore, associations between PM2.5 and age-related cataracts were also demonstrated in RCS models. The PAF of age-related cataracts to PM2.5 in the total participants was 24.63%. Our research found that long-term exposure to PM2.5 may increase the risk of age-related cataracts, and age-related cataracts should be considered as an important public health issue due to air pollution.

Environmental influences on ophthalmic conditions: A scoping review

BACKGROUND

Environmental factors have been implicated in various eye pathologies. The purpose of this review is to synthesise the published research on environmental effects on eye disease.

METHODS

Four databases were searched for terms relating to environmental exposures and ophthalmic disease. Titles and abstracts were screened followed by full-text review. Data was extracted from 118 included studies. Quality assessment was conducted for each study.

RESULTS

Air pollutants, including nitrogen dioxide, nitrites, sulphur dioxide, particulate matter, carbon monoxide, ozone and hydrocarbons are associated with ocular conditions ranging from corneal damage to various retinopathies, including central retinal artery occlusion. Certain chemicals and metals, such as cadmium, are associated with increased risk of age-related macular degeneration. Climate factors, such as sun exposure, have been associated with the development of cataracts. Living in rural areas was associated with various age-related eye diseases whereas people living in urban settings had higher risk for dry eye disease and uveitis.

CONCLUSION

Environmental exposures in every domain are associated with various ophthalmic conditions. These findings underscore the importance of continued research on the interplay between the environment and eye health.

Ambient Air Pollution and Age-Related Eye Disease: A Systematic Review and Meta-Analysis

Purpose

To compare the burden of age-related eye diseases among adults exposed to higher versus lower levels of ambient air pollutants.

Methods

MEDLINE, EMBASE, and Scopus were searched for relevant articles until September 30, 2021. Inclusion criteria included studies of adults, aged 40+ years, that provided measures of association between the air pollutants (nitrogen dioxide, carbon monoxide [CO], sulfur dioxide, ozone [O3], particulate matter [PM] less than 2.5 µm in diameter [PM2.5], and PM less than 10 µm in diameter [PM10]) and the age-related eye disease outcomes of glaucoma, age-related macular degeneration (AMD), or cataract. Pooled odds ratio (OR) estimates and 95% confidence intervals (CIs) were calculated using a random-effects meta-analysis model. PROSPERO registration ID: CRD42021250078.

Results

A total of eight studies were included in the review. Consistent evidence for an association was found between PM2.5 and glaucoma, with four of four studies reporting a positive association. The pooled OR for each 10-µg/m3 increase of PM2.5 on glaucoma was 1.18 (95% CI, 0.95-1.47). Consistent evidence was also found for O3 and cataract, with three of three studies reporting an inverse association. Two of two studies reported a null association between PM2.5 and cataract, while one of one studies reported a positive association between PM10 and cataract. One of one studies reported a positive relationship between CO and AMD. Other relationships were less consistent between studies.

Conclusions

Current evidence suggests there may be an association between some air pollutants and cataract, AMD, and glaucoma.

Long-term exposure to ambient air pollutants and age-related macular degeneration in middle-aged and older adults

Absract In developed countries, age-related macular degeneration (AMD) is a leading cause of irreversible blindness in adults. The key pathways of AMD are suggested to be excessive oxidative stress and inflammation in the central retina. Because air pollution has been found capable of inducing oxidative stress and inflammation, it may play a role in development of AMD. This study investigated the association between ambient air pollution and AMD in 15,115 middle-aged and older adults (≥40 years) from Korean National Health and Nutrition Examination Survey 2008-2012. After controlling for important confounders, ambient NO₂ and CO in current-to-5 prior years and PM₁₀ in 2-to-5 prior years were significantly associated with higher prevalence of early AMD, while O₃ in current-to-5 prior years was significantly associated with lower prevalence of early AMD. When modeled air pollution within administrative division units, its ORs with an IQR increase in NO₂, CO, and O₃ at current year were 1.24 (95% CI: 1.05-1.46), 1.22 (95% CI: 1.09-1.38), and 0.80 (95% CI: 0.70-0.92), respectively. Overall, results from air pollution at local/town units were consistent with those at administrative division units. Long-term exposures to ambient air pollution may play a role in the risk of AMD in middle-aged and older adults.

The Association of Ambient Air Pollution With Cataract Surgery in UK Biobank Participants: Prospective Cohort Study

Purpose

Air pollution is associated with chronic diseases of later life. Cataract is the most common cause of blindess globally. It is biologically plausible that cataract risk is increased by pollution exposure. Therefore, the relationship between air pollution and incident cataract surgery was examined.

Methods

This was a prospective, observational study involving 433,727 UK Biobank participants. Ambient air pollution measures included particulates, nitrogen dioxide (NO2) and nitrogen oxides (NOx). Outdoor air pollution was estimated based on land use regression models. Participants undergoing cataract surgery in either eye were ascertained via data linkage to the National Health Service procedure statistics. Those undergoing cataract surgery within 1 year of baseline assessment and those reporting cataract at baseline were excluded. Cox proportional hazards models were used to examine the associations between air pollutants and incident cataract surgery, adjusting for sociodemographic and lifestyle factors.

Results

There were 16,307 incident cases of cataract surgery. Higher exposure to PM2.5 was associated with a 5% increased risk of incident cataract surgery (per interquartile range [IQR] increase). Compared to the lowest quartile, participants with exposures to PM2.5, NO2, and NOx in the highest quartile were 14%, 11%, and 9% more likely to undergo cataract surgery, respectively. A continuous exposure-response relationship was observed, with the likelihood of undergoing cataract surgery being progressively higher with greater levels of PM2.5, NO2, and NOx (P for trend P < 0.001).

Conclusions

Although the results of our study showed a 5% increased risk of future cataract surgery following an exposure to PM2.5, NO2, and NOx, the effect estimates were relatively small. Further research is required to determine if the associations identified are causal.

Fine Particulate Matter and Age-Related Eye Disease: The Canadian Longitudinal Study on Aging

Purpose

To determine the relationship between fine particulate matter (PM2.5) and ocular outcomes such as visual impairment and age-related eye disease.

Methods

Baseline data were used from the Canadian Longitudinal Study on Aging. The Comprehensive Cohort consisted of 30,097 adults ages 45 to 85 years. Annual mean PM2.5 levels (µg/m3) for each participant's postal code were estimated from satellite data. Ozone, sulfur dioxide, and nitrogen dioxide levels were also estimated. Binocular presenting visual acuity was measured using a visual acuity chart. Intraocular pressure (IOP) was measured in millimeters of mercury using the Reichart Ocular Response Analyzer. Participants were asked about a diagnosis of glaucoma, macular degeneration, or cataract. Logistic and linear regression models were used.

Results

The overall mean PM2.5 level was 6.5 µg/m3 (SD = 1.8). In the single pollutant models, increased PM2.5 levels (per interquartile range) were associated with visual impairment (odds ratio [OR] = 1.12; 95% confidence interval [CI], 1.02-1.24), glaucoma (OR = 1.14; 95% CI, 1.01-1.29), and visually impairing age-related macular degeneration (OR = 1.52; 95% CI, 1.10-2.09) after adjustment for sociodemographics and disease. PM2.5 had a borderline adjusted association with cataract (OR = 1.06; 95% CI, 0.99-1.14). In the multi-pollutant models, increased PM2.5 was associated with glaucoma and IOP only after adjustment for sociodemographics and disease (OR = 1.24; 95% CI, 1.05-1.46 and β = 0.24; 95% CI, 0.12-0.37).

Conclusions

Increased PM2.5 is associated with glaucoma and IOP. These associations should be confirmed using longitudinal data and potential mechanisms should be explored. If confirmed, this work may have relevance for revision of World Health Organization thresholds to protect human health.

Association between Exposure to Ambient Air Pollution and Age-Related Cataract: A Nationwide Population-Based Retrospective Cohort Study

This study aimed to investigate the association between ambient air pollutants and cataracts in the general population aged 50 years or older using data from the Korean National Insurance Service-National Sample Cohort. Cataract patients were defined as those diagnosed by a physician and having undergone cataract surgery. After matching the average concentrations of PM2.5, PM10, NO2, CO, SO2, and O3 in residential areas, the association between quartile level of air pollutants and incidence of cataract was analyzed using a multivariate Cox-proportional hazard risk model. Among the 115,728 participants, 16,814 (14.5%) were newly diagnosed with cataract and underwent related surgery between 1 January 2004, and 31 December 2015. Exposure to PM10, NO2, and SO2 was positively associated with cataract incidence, while O3 was negatively associated. The adjusted hazard ratio (HR) with 95% confidence interval was 1.069 (1.025-1.115) in PM10 and 1.080 (1.030-1.133) in NO2. However, the association between cataract and the quartile of PM2.5 measured during one year in 2015 was not clear. The HR of female participants aged 65 or older was significantly increased according to quartile of air pollutants. We identified exposure to PM10, NO2, SO2, and O3 associated with cataract development in Korean adults aged ≥ 50 years. This information may be helpful for policymaking to control air pollution as a risk factor for eye health.