Impact of environmental pollution on the eye

Understanding the Dry Eye Disease-Related Symptoms in South America: Prevalence and Associated Factors-A Systematic Review

Background/Objectives: Dry eye disease is a leading cause of ophthalmologic consultations worldwide and can significantly impact quality of life. While global prevalence rates vary widely, data specific to South America are limited. This systematic review aims to describe and analyze the prevalence and associated factors of dry eye disease-related symptoms in South American populations. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review was conducted using databases such as PubMed, Web of Science, Scopus, and LILACS. Primary studies in English and Spanish that examined the prevalence of dry eye disease-related symptoms in South American populations and its associated factors were included without date restrictions. Studies were screened and selected based on predefined inclusion and exclusion criteria, resulting in the final inclusion of 16 studies from six South American countries. Results: This review identified significant variability in the prevalence of dry eye disease-related symptoms in South American populations in the region, ranging from 4% to 77.5%, with a mean prevalence of 39.3%. Higher prevalence rates were observed among specific groups, such as university students (58.6%) and administrative workers (57.9%). Factors associated with dry eye disease-related symptoms in South American populations included female sex, older age, prolonged screen time, insufficient sleep, and medical conditions such as hypertension, connective tissue disorders, and the use of medications like antihypertensives and antidepressants. Conclusions: The prevalence of dry eye disease-related symptoms in South American populations is notably higher than global averages, highlighting regional challenges. This study emphasizes the need for standardized diagnostic tools and comprehensive epidemiological research across South America, particularly in underrepresented countries, to inform public health strategies tailored to the specific needs of these populations.

Greater exposure to PM2.5 and PM10 was associated with lower corneal nerve measures: the Maastricht study - a cross-sectional study

BACKGROUND

Epidemiological and toxicological studies indicate that increased exposure to air pollutants can lead to neurodegenerative diseases. To further confirm this relationship, we evaluated the association between exposure to ambient air pollutants and corneal nerve measures as a surrogate for neurodegeneration, using corneal confocal microscopy.

METHODS

We used population-based observational cross-sectional data from The Maastricht Study including N = 3635 participants (mean age 59.3 years, 51.6% were women, and 19.9% had type 2 diabetes) living in the Maastricht area. Using the Geoscience and hEalth Cohort COnsortium (GECCO) data we linked the yearly average exposure levels of ambient air pollutants at home address-level [particulate matter with diameters of ≤ 2.5 µm (PM2.5), and ≤ 10.0 µm (PM10), nitrogen dioxide (NO2), and elemental carbon (EC)]. We used linear regression analysis to study the associations between Z-score for ambient air pollutants concentrations (PM2.5, PM10, NO2, and EC) and Z-score for individual corneal nerve measures (corneal nerve bifurcation density, corneal nerve density, corneal nerve length, and fractal dimension).

RESULTS

After adjustment for potential confounders (age, sex, level of education, glucose metabolism status, corneal confocal microscopy lag time, inclusion year of participants, smoking status, and alcohol consumption), higher Z-scores for PM2.5 and PM10 were associated with lower Z-scores for corneal nerve bifurcation density, nerve density, nerve length, and nerve fractal dimension [stβ (95% CI): PM2.5 -0.10 (-0.14; -0.05), -0.04 (-0.09; 0.01), -0.11 (-0.16; -0.06), -0.20 (-0.24; -0.15); and PM10 -0.08 (-0.13; -0.03), -0.04 (-0.09; 0.01), -0.08 (-0.13; -0.04), -0.17 (-0.21; -0.12)], respectively. No associations were found between NO2 and EC and corneal nerve measures.

CONCLUSIONS

Our population-based study demonstrated that exposure to higher levels of PM2.5 and PM10 are associated with higher levels of corneal neurodegeneration, estimated from lower corneal nerve measures. Our results suggest that air pollution may be a determinant for neurodegeneration assessed in the cornea and may impact the ocular surface health as well.

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 Between Area Temperature and Severe Vision Impairment in a Nationally Representative Sample of Older Americans

PURPOSE

Several small studies have associated exposure to elevated average temperature with specific vision problems. However, no large-scale studies have examined the relationship between vision impairment and average area temperature in the general population. We conducted a cross-sectional analysis of a large nationally representative sample of older adults to further explore this relationship.

METHODS

Secondary analysis of the American Community Survey (ACS). The survey was conducted through mail, telephone and in-person interviews. Data from six consecutive years of the cross-sectional survey were analysed (2012-2017). The subsample analysed included community-dwelling and institutionalized older adults aged 65 and older in the coterminous US who lived in the same state in which they were born (n = 1,707,333). The question on severe vision impairment was "Is this person blind or does he/she have serious difficulty seeing even when wearing glasses?". Average annual temperature data from the National Oceanic and Atmospheric Administration was combined into a 100-year average and mapped to corresponding US Census Bureau's public use microdata areas from the ACS.

RESULTS

Higher average temperature is consistently associated with increased odds of severe vision impairment across all cohorts (i.e. age, sex, race, income, and educational attainment cohorts) with the exception of Hispanic older adults. Compared to those who lived in counties with average temperature of < 50 °F (< 10 °C) , the odds of severe vision impairment were 44% higher in counties with average temperature of 60 °F (15.5 °C) or above (OR 1.44; 95% CI 1.42-1.46).

CONCLUSION

If the association is found to be causal, the predicted rise in global temperatures could impact the number of older Americans affected by severe vision impairment and the associated health and economic burden.

Particulate Matter Induced Adverse Effects on Eye Development in Zebrafish (Danio rerio) Embryos

Particulate matter (PM) can cause human diseases, particularly respiratory diseases. Since eyes are directly exposed to the air, they might be directly adversely affected by PM. Therefore, we determined the toxicity caused to eye development by PM using zebrafish (Danio rerio) embryos. The PM-induced embryo toxicity was dependent on dose and time and caused significant morphological defects, reducing the total body length and the total eye area. Reactive oxygen species (ROS) overproduction was confirmed in the PM treatment group, and antioxidant genes (cat and sod2), photoreceptor cell development, pigmentation genes (atoh8, vsx1, and rho), eye-embryogenesis genes (pax6a and pax6b), and eye-lens-development genes (cryaa) were downregulated, while eye-development genes (crybb1) were upregulated. In conclusion, PM had a direct adverse effect on the eyes, and zebrafish embryos can be used as a model to evaluate PM-induced eye toxicity in vivo.

Emerging roles of air pollution and meteorological factors in autoimmune eye diseases

Autoimmune eye diseases (AEDs), a collection of autoimmune inflammatory ocular conditions resulting from the dysregulation of immune system at the ocular level, can target both intraocular and periorbital structures leading to severe visual deficit and blindness globally. The roles of air pollution and meteorological factors in the initiation and progression of AEDs have been increasingly attractive, among which the systemic and local mechanisms are both involved in. Exposure to excessive air pollution and extreme meteorological conditions including PM2.5/PM0.1, environmental tobacco smoke, insufficient sunshine, and high temperature, etc., can disturb Th17/Treg balance, regulate macrophage polarization, activate neutrophils, induce systemic inflammation and oxidative stress, decrease retinal blood flow, promote tissue fibrosis, activate sympathetic nervous system, adversely affect nutrients synthetization, as well as induce heat stress, therefore may together deteriorate AEDs. The crosstalk among inflammation, oxidative stress and dysregulated immune system appeared to be prominent. In the present review, we will concern and summarize the potential mechanisms underlying linkages of air pollution and meteorological factors to ocular autoimmune and inflammatory responses. Moreover, we concentrate on the specific roles of air pollutants and meteorological factors in several major AEDs including uveitis, Graves' ophthalmopathy (GO), ocular allergic disease (OAD), glaucoma, diabetic retinopathy (DR), etc.

TFOS Lifestyle Report: Impact of environmental conditions on the ocular surface

Environmental risk factors that have an impact on the ocular surface were reviewed and associations with age and sex, race/ethnicity, geographical area, seasonality, prevalence and possible interactions between risk factors are reviewed. Environmental factors can be (a) climate-related: temperature, humidity, wind speed, altitude, dew point, ultraviolet light, and allergen or (b) outdoor and indoor pollution: gases, particulate matter, and other sources of airborne pollutants. Temperature affects ocular surface homeostasis directly and indirectly, precipitating ocular surface diseases and/or symptoms, including trachoma. Humidity is negatively associated with dry eye disease. There is little data on wind speed and dewpoint. High altitude and ultraviolet light exposure are associated with pterygium, ocular surface degenerations and neoplastic disease. Pollution is associated with dry eye disease and conjunctivitis. Primary Sjögren syndrome is associated with exposure to chemical solvents. Living within a potential zone of active volcanic eruption is associated with eye irritation. Indoor pollution, "sick" building or house can also be associated with eye irritation. Most ocular surface conditions are multifactorial, and several environmental factors may contribute to specific diseases. A systematic review was conducted to answer the following research question: "What are the associations between outdoor environment pollution and signs or symptoms of dry eye disease in humans?" Dry eye disease is associated with air pollution (from NO2) and soil pollution (from chromium), but not from air pollution from CO or PM10. Future research should adequately account for confounders, follow up over time, and report results separately for ocular surface findings, including signs and symptoms.

Meandered and muddled: a systematic review on the impact of air pollution on ocular health

From the years 1970-2023, a systematic overview of the diverse consequences of particulate matter on eye health and a disease classification according to acute, chronic, and genetic are presented using the PubMed, Research Gate, Google Scholar, and Science Direct databases. Various studies on medical aspects correlate with the eye and health. However, from an application perspective, there is limited research on the ocular surface and air pollution. The main objective of the study is to uncover the relationship between eye health and air pollution, particularly particulate matter, along with other external factors acting as aggravators. The secondary goal of the work is to examine the existing models for mimicking human eyes. The study is followed by a questionnaire survey in a workshop, in which the exposure-based investigation was tagged based on their activity. This paper establishes a relationship between particulate matter and its influence on human health, leading to numerous eye diseases like dry eyes, conjunctivitis, myopia, glaucoma, and trachoma. The results of the questionnaire survey indicate that about 68% of the people working in the workshop are symptomatic with tears, blurred vision, and mood swings, while 32% of the people were asymptomatic. Although there are approaches for conducting experiments, the evaluation is not well defined; empirical and numerical solutions for particle deposition on the eye are needed. There prevails a broad gap in the arena of ocular deposition modeling.

Toxic External Exposure Leading to Ocular Surface Injury

The surface of the eye is directly exposed to the external environment, protected only by a thin tear film, and may therefore be damaged by contact with ambient particulate matter, liquids, aerosols, or vapors. In the workplace or home, the eye is subject to accidental or incidental exposure to cleaning products and pesticides. Organic matter may enter the eye and cause infection. Ocular surface damage can trigger a range of symptoms such as itch, discharge, hyperemia, photophobia, blurred vision, and foreign body sensation. Toxin exposure can be assessed clinically in multiple ways, including via measurement of tear production, slit-lamp examination, corneal staining, and conjunctival staining. At the cellular level, environmental toxins can cause oxidative damage, apoptosis of corneal and conjunctival cells, cell senescence, and impaired motility. Outcomes range from transient and reversible with complete healing to severe and sight-compromising structural changes. Classically, evaluation of tolerance and safety was carried out using live animal testing; however, new in vitro and computer-based, in silico modes are superseding the gold standard Draize test. This review examines how environmental features such as pollutants, temperature, and seasonality affect the ocular surface. Chemical burns to the eye are considered, and approaches to protect the ocular surface are detailed.

Correlation Between Air Quality Index and Tear Film Lipid Layer Thickness: Comparison Between Patients with Sjogren's Syndrome and with Meibomian Gland Dysfunction

Purpose: To evaluate the effect of air pollution on the tear film stability by analyzing the correlation between Air Quality Index (AQI) and Lipid Layer thickness (LLT) in Xuzhou.Methods: As a prospective descriptive observational study, 284 patients with meibomian gland dysfunction (MGD), 157 patients with Sjögren's syndrome (SS), and 264 healthy volunteers were included. The tear film lipid layer thickness of the three groups of subjects was measured weekly and compared with the air quality index to analyze the correlation between the two indicators. Logistic regression analysis and linear regression analysis were used to analyze the effect of AQI on the thickness of the tear film lipid layer. The change of LLT with air pollution at different AQI levels was also analyzed.Results: There are obvious seasonal differences in the changes of air pollution index in Xuzhou. Significant differences could be observed in the thickness of the lipid layer of the tear film among the three groups. LLT in the MGD group and SS group decreased with the aggravation of air pollution, while remained unchanged in the control group. There was strong evidence of correlation between LLT of the MGD group (F = 353.494, p < 0.01, adjusted R2 = 0.695) and the SS group (F = 502.404, p < 0.01, adjusted R2 = 0.764) with AQI, while there was minor correlation between LLT with AQI in control group (F = 8.525, p < 0.01, adjusted R2 = 0.046).Conclusions: Air pollution can cause a decrease in the thickness of the tear film lipid layer, thereby affecting tear film stability, leading to the occurrence of dry eye.

Evidence of air pollution-related ocular signs and altered inflammatory cytokine profile of the ocular surface in Beijing

We evaluated how different degrees of air pollution affect the ocular surface of a cohort of human subjects in Beijing by correlating in-patient test outcomes with tear cytokines. A cross-sectional study involving 221 volunteers was carried out in different districts of Beijing. Air pollution indices were recorded for 7 d (including the visit day). The indices recorded were the air quality index (AQI), which is a dimensionless measure that quantitatively describes the state of air quality, concentrations of particulate matter smaller than 2.5 μm (PM2.5) and 10 μm (PM10), sulfur dioxide (SO₂), ozone (O₃), and nitrogen dioxide (NO₂). The Ocular Symptom Disease Index (OSDI) questionnaire provided. Subsequently, subjects underwent slit-lamp examination, which included meibomian gland examination, conjunctival congestion score, conjunctivochalasis grade, tear meniscus height (TMH), tear breakup time (TBUT), corneal fluorescein staining (CFS), Schirmer I test, and conjunctival impression cytology. The concentrations of vascular endothelial growth factor (VEGF), interleukins (IL)-1β, IL-6 and IL-8 in tears were measured by microsphere-based immunoassay analysis. According to the value of the AQI, participants are divided into a slightly polluted (SP) group (n = 103) which the AQI value is less than or equal to 100 and a heavily polluted (HP) group (n = 118) whose AQI value is more than 100. Air pollution is related to ocular discomfort based on tear cytokine concentrations. PM2.5, PM10 and NO₂ were positively correlated with OSDI, MG expressibility, meibum score, meiboscore, conjunctival congestion score, Schirmer I test value, TMH, goblet-cell density, concentrations of IL-6, and VEGF were negatively correlated with TBUT. PM2.5 and PM10 appear to be the major risk factors to the ocular surface, with NO₂ being another important risk factor based on this study. The symptoms and signs of eye discomfort in the SP group were significantly less severe than those in the HP group, and tear cytokine concentrations (IL-6 and VEGF) were lower. Air pollution degrees were significantly correlated with tear cytokine concentrations, indicating an alteration of cytokine balance at the ocular surface under different degrees of air pollution.

Trace Elements in Tears: Comparison of Rural and Urban Populations Using Particle Induced X-ray Emission

We aimed to evaluate the types and concentrations of trace elements in tears of individuals living in urban and rural environments using particle induced X-ray emission (PIXE) and the possible association with exposure to air pollution and suggest a novel method for tear-based biomonitoring studies. This cross-sectional pilot study comprised 42 healthy subjects, 28 living in a rural area and 14 in an industrial city. Tears were collected with Schirmer paper and characterized by PIXE. Trace element concentrations from both eyes were averaged together with environmental pollution data. Main outcome measures were between-group differences in types and concentrations of trace elements in tears and comparison to environmental data. The rural group included 12/28 men, mean age 45.2 ± 14.8 years. The urban group consisted of 11/14 men of mean age 27 ± 5.9 years. Six rural and all urban were active smokers. Air pollution data showed more toxic elements in the rural environment. On PIXE analysis, chlorine, sodium, and potassium were found in similar concentrations in all samples. Normalizing to chlorine yielded higher values of aluminum, iron, copper, and titanium in the rural group; aluminum was found only in the rural group. The higher levels of certain trace elements in the rural group may, in part, be a consequence of exposure to specific environmental conditions. No direct association was found with air pollution data. PIXE is useful to analyze trace elements in tears, which might serve as a marker for individual exposure to environmental pollutants in biomonitoring studies.

Dry eye syndrome: comprehensive etiologies and recent clinical trials

Dry eye syndrome (DES) is multifactorial and likely to be a cause of concern more so than ever given the rapid pace of modernization, which is directly associated with many of the extrinsic causative factors. Additionally, recent studies have also postulated novel etiologies that may provide the basis for alternative treatment methods clinically. Such insights are especially important given that current approaches to tackle DES remains suboptimal. This review will primarily cover a comprehensive list of causes that lead to DES, summarize all the upcoming and ongoing clinical trials that focuses on treating this disease as well as discuss future potential treatments that can improve inclusivity.

Occupational ocular health problems among marble workers at Shaq El Tho'ban industrial area in Egypt

Eye health of the working population is an essential condition for productivity. Marble industry is processed at large scale at Shaq El Tho'ban area where much dust, crushed pieces of stone, and fluctuating temperatures are endangering employees' health generally and eye health specifically. The objectives of this study were assessing the prevalence of the most common ocular health problems associated with marble industry and investigating the impact of the working environment and occupational risk factors on the oculo-visual status of marble workers. A cross-sectional study was conducted among 250 workers, working at Shaq El Tho'ban area in Egypt during the period from August 2020 to September 2021, using a semi-structured questionnaire and eye examination comprised of full ocular history, visual acuity testing (unaided/aided), slit lamp examination, ophthalmoscopy, and Schirmer's type I and tear break up time tests. The current study showed that gritty sensation (65.2%) and eye dryness (51.2%) were the commonest symptoms complained. By examination, conjunctival hyperemia (59.6%) was the most prevalent finding. By performing dry eye tests, dry eye was diagnosed in 60.4% and 51.2% of workers by Schirmer's test and tear break up time test respectively. The study's results indicated that age, working category, smoking, and diabetes had significant impact on development of ocular symptoms, while working duration, diabetes, smoking, ocular symptoms, and ocular foreign body had significant impact on development of dry eye disease. Implementation of engineering control measures, proper designing, and supply of eye PPE together with adequate health education to all workers about occupational health risks and preventive measures are recommended.

Lignin and Keratin-Based Materials in Transient Devices and Disposables: Recent Advances Toward Materials and Environmental Sustainability

Rising concerns and the associated negative implications of pollution from e-waste and delayed decomposition and mineralization of component materials (e.g., plastics) are significant environmental challenges. Hence, concerted pursuit of accurate and efficient control of the life cycle of materials and subsequent dematerialization in target environments has become essential in recent times. The emerging field of transient technology will play a significant role in this regard to help overcome current environmental challenges by enabling the use of novel approaches and new materials with unique functionalities to produce devices and materials such as disposable diagnostic devices, flexible solar panels, and foldable displays that are more ecologically benign, low-cost, and sustainable. The prerequisites for materials employed in transient devices and disposables include biodegradability, biocompatibility, and the inherent ability to mineralize or dissipate in target environments (e.g., body fluids) in a short lifetime with net-zero impact. Biomaterials such as lignin and keratin are well-known to be among the most promising environmentally benign, functional, sustainable, and industrially applicable resources for transient devices and disposables. Consequently, considering the current environmental concerns, this work focuses on the advances in applying lignin and keratin-based materials in short-life electronics and single-use consumables, current limitations, future research outlook toward materials, and environmental sustainability.

The Adverse Effects of Air Pollution on the Eye: A Review

Air pollution is inevitably the result of human civilization, industrialization, and globalization. It is composed of a mixture of gases and particles at harmful levels. Particulate matter (PM), nitrogen oxides (NOx), and carbon dioxides (CO₂) are mainly generated from vehicle emissions and fuel consumption and are the main materials causing outdoor air pollution. Exposure to polluted outdoor air has been proven to be harmful to human eyes. On the other hand, indoor air pollution from environmental tobacco smoking, heating, cooking, or poor indoor ventilation is also related to several eye diseases, including conjunctivitis, glaucoma, cataracts, and age-related macular degeneration (AMD). In the past 30 years, no updated review has provided an overview of the impact of air pollution on the eye. We reviewed reports on air pollution and eye diseases in the last three decades in the PubMed database, Medline databases, and Google Scholar and discussed the effect of various outdoor and indoor pollutants on human eyes.

Impact of Climate Change on Eye Diseases and Associated Economical Costs

Climate change generates negative impacts on human health. However, little is known about specific impacts on eye diseases, especially in arid and semi-arid areas where increases in air temperatures are expected. Therefore, the main goals of this research are: (i) to highlight the association between common eye diseases and environmental factors; and (ii) to analyze, through the available literature, the health expenditure involved in combating these diseases and the savings from mitigating the environmental factors that aggravate them. Mixed methods were used to assess the cross-variables (environmental factors, eye diseases, health costs). Considering Southern Spain as an example, our results showed that areas with similar climatic conditions could increase eye diseases due to a sustained increase in temperatures and torrential rains, among other factors. We highlight that an increase in eye diseases in Southern Spain is conditioned by the effects of climate change by up to 36.5%; the economic burden of the main eye diseases, extrapolated to the rest of the country, would represent an annual burden of 0.7% of Spain's Gross Domestic Product. In conclusion, the increase in eye diseases has a strong economic and social impact that could be reduced with proper management of the effects of climate change. We propose a new concept: disease sink, defined as any climate change mitigation action which reduces the incidence or morbidity of disease.

Exposure to Ambient NO2 Increases the Risk of Dry Eye Syndrome in Females: An 11-Year Population-Based Study

Previous studies have indicated that women suffer from dry eye syndrome (DES) more significantly than men. Therefore, we specifically explore the associations between air pollutant levels and the risks of DES for women. The study obtained 27,605 participants from the 29 recruitment centers of the Taiwan Biobank, which was established in October 2012. A large scale cross-sectional study involving DES sufferers and age- and education-matched control groups without DES was designed. Based on the municipality of residence, the predicted concentration levels of various air pollutants, including PM_2.5, sulfur dioxide (SO₂), ozone (O₃), and nitrogen dioxide (NO₂) were estimated by using hybrid kriging/LUR model. Multiple logistic regressions were applied to estimate the prevalence ratios (PR) of DES and 95% confidence interval. Hormone supplementations, DBP, allergies, and arthritis were considered as important comorbidities for increased PR risk of DES. In addition, with each standard deviation (SD) increment of PM_2.5 and temperature, women had significant increases in PRs of DES of 1.09- and 1.07-fold, respectively; conversely, each SD increment of relative humidity (RH) had a protective effect against the risk of DES. After considering hormone supplementation, arthritis, and allergy, the SD increment of NO₂ and temperature were associated with the PRs of DES. In conclusion, significant associations of ambient NO₂ concentration, RH and temperature with DES indicated the importance of increased environmental protection in the female population. Female exposure to high levels of NO₂ when receiving hormone supplementation, or suffering with allergies or arthritis, had significantly increased risk of DES.

Trace elements exposure and risk in age-related eye diseases: a systematic review of epidemiological evidence

This systematic review aimed to evaluate existing evidence on the associations between trace elements exposure and age-related eye diseases. PubMed and Google scholar databases were searched for epidemiological and postmortem studies on the relationship between exposure to trace elements and Age-related eye diseases such as age-related macular degeneration (AMD), cataract, glaucoma and diabetic retinopathy (DR), in population groups aged 40 years and above. Available evidence suggests that cadmium (Cd) exposure may be positively associated with the risks of AMD and cataract. There is also evidence that exposure to lead (Pb) may be positively associated with higher risk of cataract and glaucoma. There is limited number of relevant studies and lack of prospective studies for most of the investigated associations. Evidence for other trace elements is weak and inconsistent, and the number of available studies is small. Likewise, there are very few relevant studies on the role of trace elements in DR. Chemical elements that affect the distribution and absorption of other trace elements have never been investigated. The suggestive but limited evidence motivates large and quality prospective studies to fully characterize the impact of exposure to trace (toxic and essential) elements on age-related eye diseases.

Environmental and Air Pollution Factors Affecting Allergic Eye Disease in Children and Adolescents in India

The aim of this study was to describe the correlation between the meteorological and air pollution parameters with the temporal pattern of presentation of recent onset allergic eye disease (AED). This cross-sectional hospital-based study included new patients (≤21 years of age) presenting between January 2016 and August 2018 from the district of Hyderabad with a clinical diagnosis of AED and an acute exacerbation of recent onset of symptoms of less than 3 months duration. Correlation analysis was performed with the local environmental rainfall, temperature, humidity, windspeed, and air pollution. Of the 25,354 new patients hailing from the district of Hyderabad, 2494 (9.84%) patients were diagnosed with AED, of which 1062 (4.19%) patients had recent onset of symptoms. The mean monthly prevalence in this cohort was 4.13%, and the month of May (6.09%) showed the highest levels. The environmental parameters of humidity (r² = 0.83/p = < 0.0001) and rainfall (r² = 0.41/p = 0.0232) showed significant negative correlation, while temperature (r² = 0.43/p = 0.0206) and ground-level ozone (r² = 0.41/p = 0.0005) showed significant positive correlation with the temporal pattern of AED in the population. An increase in rainfall and humidity was associated with a lower prevalence, and an increase of temperature and ground-level ozone was associated with a higher prevalence of AED cases during the year among children and adolescents.

Temporal Trends over a Decade in Serious Vision Impairment in a Large, Nationally Representative Population-based Sample of Older Americans: Gender, Cohort and Racial/Ethnic Differences

Purpose: The objectives of this study are:1)To identify temporal trends in the age-sex-race/ethnicity adjusted prevalence of vision impairment among Americans aged 65+ from 2008-2017; To determine if these temporal trends in vision impairment differ by 2)gender and age cohort, and 3)race/ethnicity, and; 4)To investigate if improvements in cohort educational attainment partially attenuate these trends.Methods: Secondary analysis of 10 years of annual nationally-representative data from the American Community Survey with 5.4 million community-dwelling and institutionalized older adults aged 65+. The question on vision impairment was "Is this person blind or does he/she have serious difficulty seeing even when wearing glasses?".Results: The prevalence of serious vision impairment in the US population aged 65+ declined from 8.3% to 6.6% between 2008 and 2017. There would have been an additional 848,000 older Americans with serious vision impairment in 2017 if rates had remained at the 2008 level. After age, sex and race/ethnicity were controlled, women had a 2.1% per year decline in the odds of vision impairment (OR = 0.979; CI = 0.977, 0.980), which represents a 21% decline over the decade, and men had a 9% decline over the decade (OR = 0.991; CI = 0.989, 0.993). Adjusting for education attenuated the decade decline among women, reducing it to 13%, and completely attenuated the decline among men. Most of the decline was among those aged 75+. Racial/ethnic disparities narrowed over the decade.Conclusion: Between 2008 and 2017, the prevalence of serious vision impairment among older Americans declined significantly, with steeper declines among African Americans and Hispanic Americans than among non-Hispanic White Americans.

Bisphenol A Exposure Changes the Transcriptomic and Proteomic Dynamics of Human Retinoblastoma Y79 Cells

Bisphenol A (BPA) is a xenoestrogen chemical commonly used to manufacture polycarbonate plastics and epoxy resin and might affect various human organs. However, the cellular effects of BPA on the eyes have not been widely investigated. This study aimed to investigate the cellular cytotoxicity by BPA exposure on human retinoblastoma cells. BPA did not show cytotoxic effects, such as apoptosis, alterations to cell viability and cell cycle regulation. Comparative analysis of the transcriptome and proteome profiles were investigated after long-term exposure of Y79 cells to low doses of BPA. Transcriptome analysis using RNA-seq revealed that mRNA expression of the post-transcriptional regulation-associated gene sets was significantly upregulated in the BPA-treated group. Cell cycle regulation-associated gene sets were significantly downregulated by exposure to BPA. Interestingly, RNA-seq analysis at the transcript level indicated that alternative splicing events, particularly retained introns, were noticeably altered by low-dose BPA treatment. Additionally, proteome profiling using MALDI-TOF-MS identified a total of nine differentially expressed proteins. These results suggest that alternative splicing events and altered gene/protein expression patterns are critical phenomena affected by long-term low-dose BPA exposure. This represents a novel marker for the detection of various diseases associated with environmental pollutants such as BPA.

Risk Factors Influencing the Occurrence and Severity of Symptomatic Dry Eye Syndrome: A Cross-sectional Study

Propose: We aimed to investigate the prevalence and risk factors of dry eye syndrome (DES) among a population-based cohort study.Methods: This cross-sectional study was conducted on 475 subjects (184 men and 291 women) enrolled in the Study Group for Environmental Eye Disease at July 2013. Using the ocular surface disease index (OSDI), we measured the DES severity and defined DES as OSDI score ≥13. Current symptoms of DES and possible risk factors such as body mass index, occupations, comorbidities, exercise, smoking and drinking status were assessed by multivariate logistic regression.Results: Prevalence of DES was significantly higher in women (52.6%) than in men (41.9%) (p < .001). Compared to white-collar workers, blue-collar workers and unemployed persons showed significantly higher DES prevalence and severity. Compared to those with low BMI (<23.0 kg/m²), people with extremely high BMI (≥30.0 kg/m²) had significantly higher odds ratio (OR) of having DES after fully adjusted for sex, age, hypertension, diabetes, menopausal status, hormone replacement therapy, occupation, and lifestyle factors (OR: 2.83, 95% confidence interval: 1.04-7.71).Conclusions: We found some novel factors which have been unknown to the relationship with DES through the five years observation of the cohort. The positive associations of unemployment status, blue-collar work, alcohol habit, and obesity with DES suggests a person's comprehensive condition, not individual factors, contribute significantly in developing DES. Further studies will be helpful to understand the underlying mechanisms.

Dry eye syndrome risk factors: A systemic review

Dry eye disease has been recognized to be a global public health problem, as it has many consequences starting from daily life activities restrictions to economical costs of management. At present, there is a lack of knowledge regarding the most important risk factors for eye dryness. This problem is becoming important worldwide especially with the increase use of technology, smartphones, computers, and contact lenses. The aim of this systematic review is to determine the most relevant factors associated with dry eye symptoms to help in its early recognition, prevention and reduce its subsequent implications. PRIMSA 2009 checklist was used to conduct this systematic review. The inclusion and exclusion criteria were implemented first. Then, PubMed Database was explored for articles. The data extraction was based on three categories: Sociodemographic, diseases, and medications in the form of odds ratios. Predictive values, confidence intervals, and prevalence were recorded when the data were sufficient. This systematic review included 6 Articles and 48 evaluated variables. Female gender, contact lenses, use of computers, thyroid abnormalities, hypertension, antidepressant, and antihistamine were identified to be the strongest and the most common risk factors for dry eye syndrome.

Impact of Air Pollution and Weather on Dry Eye

Air pollution has broad effects on human health involving many organ systems. The ocular surface is an excellent model with which to study the effects of air pollution on human health as it is in constant contact with the environment, and it is directly accessible, facilitating disease monitoring. Effects of air pollutants on the ocular surface typically manifest as dry eye (DE) symptoms and signs. In this review, we break down air pollution into particulate matter (organic and inorganic) and gaseous compounds and summarize the literature regarding effects of various exposures on DE. Additionally, we examine the effects of weather (relative humidity, temperature) on DE symptoms and signs. To do so, we conducted a PubMed search using key terms to summarize the existing literature on the effects of air pollution and weather on DE. While we tried to focus on the effect of specific exposures on specific aspects of DE, environmental conditions are often studied concomitantly, and thus, there are unavoidable interactions between our variables of interest. Overall, we found that air pollution and weather conditions have differential adverse effects on DE symptoms and signs. We discuss these findings and potential mitigation strategies, such as air purifiers, air humidifiers, and plants, that may be instituted as treatments at an individual level to address environmental contributors to DE.

Long-Term Exposure to Urban Particulate Matter on the Ocular Surface and the Incidence of Deleterious Changes in the Cornea, Conjunctiva and Retina in Rats

We investigated the time-dependent deleterious ocular changes induced by urban particulate matter (UPM) in vitro and in vivo. UPM treatment decreased human corneal epithelial cell migration and survival. Fluorescein scores were consistently increased by UPM application for 16 weeks. One week of rest at 2 or 4 weeks led to a recovery trend, whereas two weeks of rest at 8 weeks induced no change. UPM treatment decreased the tear film break-up time at 2 weeks, which was thereafter maintained until 16 weeks. No changes were found after periods of rest. UPM-treated eyes exhibited greater corneal epithelium thickness than normal eyes at 2 weeks, which recovered to normal at 4 and 8 weeks and was significantly decreased at 16 weeks. Apoptotic cell number in the epithelium was increased at 2 weeks, which remained constant except at 8 weeks. IL-6 expression in the cornea of the right eye continually increased for 16 weeks, and significant recovery was only observed at 8 weeks after 2 weeks of rest. Ocular pressure was significantly increased in the right eye at 12 and 16 weeks. Topical UPM application to the eye induced deleterious changes to various closely related parts of the eye.

A polymer-based technique to remove pollutants from soft contact lenses

PURPOSE

To demonstrate an alternative to the rinse and rub (RR) method for cleaning pollutants from the exterior surface of soft contact lenses. This proposed technique is termed Polymer on Polymer Pollutant Removal (PoPPR), which utilizes the elastic properties of polydimethylsiloxane (PDMS) to physically remove contaminants from contact lens surfaces through non-adhesive unpeeling.

METHODS

Three different ratios of setting agent to polymer PDMS (1:30, 1:40, and 1:50) were evaluated using the PoPPR method against the control method of RR with a commercial multi-purpose lens cleaning solution. Three simulated pollutants of different sizes: pollen (25-40 μm), microbeads (1-5 μm), and nanoparticles (5-10 nm), were used to test the effectiveness of both cleaning methods. The fraction of pollutants removed from each contact lens was recorded and evaluated for significance.

RESULTS

PDMS 1:40 was found to be the optimal ratio for lens cleaning using the PoPPR method. For larger particles (>10 μm), no difference was observed between conventional RR and proposed PoPPR method (p > 0.05). However, the new PoPPR technique was significantly better at removing small PM_2.5 particles (<2.5 μm) compared to the RR method, specifically for microbeads (p = 0.006) and nanoparticles (p < 0.001).

CONCLUSION

This proof-of-concept work demonstrates that the PoPPR method of cleaning contact lenses is as effective as the conventional cleaning method for larger particles such as pollen. The PoPPR method is more effective at removing extremely fine particulate pollutants, including microplastics and nanoparticles. This method offers a potentially more efficient cleaning protocol that could enhance the safety, health, and comfort of contact lens users, especially those living in regions with significant air pollution.

Association Between Occupational Physicochemical Exposures and Headache/Eyestrain Symptoms Among Korean Indoor/Outdoor Construction Workers

Background

Headache/eyestrain symptoms are common health problems that people experience in daily life. Various studies have examined risk factors contributing to headache/eyestrains, and physicochemical exposure was found to be a leading risk factor in causing such symptoms. The purpose of this study was to examine the relationship of headache/eyestrain symptoms with physicochemical exposure among Korean construction workers depended on worksite.

Methods

This study used data from the 4th Korean Workers Conditions Survey and selected 1,945 Korean construction workers as participants. Multivariable logistic regression analysis was used to determine the relationship.

Results

Exposure to vibrations among all construction workers affected the moderate exposure group [odds ratio (OR) 1.53, 95% confidence interval (CI) 1.01–2.32], the high exposure group (OR 1.77 95%CI 1.17–2.67), and the indoor high exposure group (OR 1.61, 95%CI 1.02-2.55) and among outdoor construction workers, the moderate group (OR 6.61, 95%CI 15.4–28.48) and the high group (OR 6.61, 95%CI 1.56–27.98). When exposed to mist, dust, and fumes, the indoor high exposure group was significantly affected (OR 1.63, 95%CI 1.07–2.47). All construction workers exposed to organic solvents were affected, high exposure group (OR 1.69, 95%CI 1.15–2.49) and indoor high exposure group (OR 1.77, 95%CI 1.08–2.89). The high exposure group in all construction worker (OR 1.70, 95%CI 1.20–2.42) and the indoor high exposure group (OR 1.83, 95%CI 1.17–2.89) also were affected by secondhand smoking exposure.

Conclusion

Many physicochemical exposure factors affect headache/eyestrain symptoms among construction workers, especially indoor construction workers, suggesting a deficiency in occupational hygiene and health environments at indoor construction worksites.

The impacts of individual and combined exposure to cadmium and lead on intraocular pressure, electroretinography, and residual changes in the rabbit eyes

The human eye is very vulnerable to various environmental pollutants. Cadmium (Cd) and lead (Pb) are widely spread heavy metals. The goal of the existing study is to explore the impact of single or joint exposure to Cd and Pb on the eye indicators. In this study, male New Zealand white rabbits were treated orally for 30 days with Cd (5 mg Cd Cl₂/kg bw) associated or not with Pb (12.5 mg lead acetate/kg bw). Fundus and slit lamp examinations, electroretinography (ERG), intraocular pressure (IOP), Cd and Pb residues, and the histopathological picture of the eye were studied. The results revealed that the oral dosing of Cd or Pb evoked a significant (p < 0.05) decline in a- and b-wave amplitudes, under scotopic conditions, and IOP values. Single Pb or Cd treatment showed a significant (p < 0.001) increase in their residues in the whole eye tissue of the Pb- or Cd-treated group. Eye structures of Cd- or Pb-intoxicated rabbit showed mild degenerated changes of cornea and sclera tissues with the presence of irregular variably sized eosinophilic droplets in the lens. Notably, the simultaneous exposure to Cd and Pb leads to an antagonistic outcome in all of the estimated parameters. These findings concluded that oral exposure to Cd or Pb could significantly disturb the vision but their joint exposure caused an opposing effect on nearly all of these disturbances.

Relationship between Ocular Surface Alterations and Concentrations of Aerial Particulate Matter

Purpose

To evaluate ocular surface alterations in two populations at different exposure levels to particulate matter (PM) in their living and work environments.

Methods

A cross-sectional study was conducted, including 78 volunteers from Argentina who lived and worked under different pollution levels in an urban (U; n = 44) or industrial zone (I; n = 34). Mean exposure level to PM was evaluated. Responses to the Ocular Symptom Disease Index and McMonnies questionnaire were obtained from all subjects. Subsequently, an assessment through the Schirmer I test (ST), slit lamp microscopy, vital staining, and tear breakup time was conducted. Statistical analyses with Chi-square and Bartlett's tests, as well as Student's t-tests and principal component analysis (PCA), were performed.

Results

Particles of size < 2.5 μm (PM2.5) level was significantly higher in the I group than the U group (P = 0.04). Ocular surface parameters including bulbar redness, eyelid redness, and the degree of vital staining with fluorescein (SF) and lissamine green (SLG) exhibited difference between the groups. With regards to the tear film, statistically significant differences in the ST value and meibomian gland dysfunction between the groups were detected (P = 0.003 and P = 0.02, respectively). Conjunctival SF and SLG, and ST values were identified as factors which could distinguish groups exposed to different PM levels.

Conclusion

Subjects exposed to higher levels of PM in the outdoor air presented greater ocular surface alterations. Thus, ST, SF, and SLG values could be used as convenient indicators of adverse health effects due to exposure to air pollution.

Ambient fine particulate matter and ozone higher than certain thresholds associated with myopia in the elderly aged 50 years and above

Although myopia has been largely ignored among the elderly population, there is an increased risk of myopia with advancing age. Ambient air pollution is one potential contributor to vision impairments, but few epidemiological studies have demonstrated such an association. This cross-sectional survey collected the information of 33,626 subjects aged ≥50 years in six developing countries during 2007-2010. Myopia was identified based on questions related to symptoms of myopia. The annual concentrations of fine particulate matter (PM_2.5) and ozone (O₃) were estimated with the satellite data and chemical transport model. We examined the associations between the two pollutants and myopia using mixed-effect Poisson regression models with robust variance estimation (sandwich estimation). We observed J-shaped associations between the two pollutants and myopia, and identified 12 and 54 μg/m³ as the threshold concentrations. The adjusted prevalence ratio was 1.12 (95% CI: 1.05, 1.21) and 1.26 (95% CI: 1.14, 1.38) for each standard deviation (SD) increase in PM_2.5 and O₃ concentrations above their threshold, respectively. In addition, the interaction analysis suggested a synergistic interaction of these two pollutants on myopia in the additive model, with a synergistic index of 1.81 (Bootstrapping 95% CI: 0.92, 4.94). Our results indicate that long-term exposures to PM_2.5 and O₃ might be important environmental risk factors of myopia in the elderly, and suggest that more efforts should be taken to reduce airborne PM_2.5 and O₃ levels to protect vision health.

Management Of Glaucoma In Developing Countries: Challenges And Opportunities For Improvement

Glaucoma is the leading cause of blindness in the developed and developing world. Not only is the clinical impact of this disease considerable, but associated economic and humanistic burdens - affecting patients, caregivers, and society - are substantial. Since glaucoma is an age-related disorder and populations in many developing countries are aging at a faster pace than in the developed world, increasing attention is being focused on ways to ameliorate the burdens of illness. In this paper, we examine the burdens of glaucoma with particular focus on developing countries, discuss some of the challenges that exist in delivering optimal glaucoma management within budget constraints, and bring into perspective how we could improve current healthcare systems, leverage technology, and strike an appropriate balance between cost and quality of care, thereby offering considerations to payors and policymakers in these countries that may result in longer-term cost savings, while concurrently striving to achieve the WHO Vision on the prevention of blindness and visual impairment.

Modification of lactoferrin by peroxynitrite reduces its antibacterial activity and changes protein structure

Lactoferrin (LF) is a multifunctional protein that plays important physiological roles as one of the most concentrated proteins in many human and other mammalian fluids and tissues. In particular, LF provides antibacterial properties to human milk, saliva, and tear fluid. LF also protects against stress-induced lipid peroxidation at inflammation sites through its iron-binding ability. Previous studies have shown that LF can be efficiently nitrated via biologically relevant mediators such as peroxynitrite (ONOO^- ), which are also present at high intracellular concentrations during inflammation and nitrosative stress. Here, we examine changes in antibacterial properties and structure of LF following ONOO^- treatment. The reaction induces nitration of tyrosine and tryptophan residues, which are commonly used as biomarker molecules for several diseases. Treatment with ONOO^- at a 10/1 M ratio of ONOO^- to tyrosine inhibited all antibacterial activity exhibited by native LF. Secondary structural changes in LF were assessed using circular dichroism spectroscopy. Nitration products with and without the addition of Fe³⁺ show significant reduction in alpha-helical properties, suggesting partial protein unfolding. Iron-binding capacity of LF was also reduced after treatment with ONOO^- , suggesting a decreased ability of LF to protect against cellular damage. LC-MS/MS spectrometry was used to identify LF peptide fragments nitrated by ONOO^- , including tyrosine residue Y92 located in the iron-binding region. These results suggest that posttranslational modification of LF by ONOO^- could be an important pathway to exacerbate infection, for example, in inflamed tissues and to reduce the ability of LF to act as an immune responder and decrease oxidative damage.

Ambient PM2.5 and O3 and their combined effects on prevalence of presbyopia among the elderly: A cross-sectional study in six low- and middle-income countries

BACKGROUND

Ambient air pollutant directly contacts with the eyes, however, the effect of ambient fine particulate matter (PM_2.5) and ozone (O₃) on vision impairment, such as presbyopia, has been kept largely unknown.

METHODS

We surveyed a total of 36,620 participants aged 50 years and above in six low- and middle-income countries. Ambient annual concentrations of PM_2.5 and O₃ for the residential community were estimated using satellite data and chemical transport model. A mixed effects model was utilized to assess the effects of ambient PM_2.5 and O₃ on presbyopia, as well as their combined effects.

RESULTS

A total of 13,841 presbyopia cases were identified among the participants with a prevalence rate of 41.17%. For both PM_2.5 and O₃, we found a J-shaped exposure-response relationship with the threshold being identified at 15 μg/m³ for PM_2.5 and 55 μg/m³ for O₃. The odds ratio (OR) of presbyopia was 1.15 (95% CI: 1.09, 1.21) for each 10 μg/m³ increase in PM_2.5 above 15 μg/m³ and 1.37 (95% CI: 1.23, 1.54) for O₃ above 55 μg/m³ after adjusting for various potential confounding factors. There appeared to be a synergistic interaction between ambient PM_2.5 and O₃ on presbyopia in the additive model, the combined effect was significantly larger than the sum of their individual effects, with a synergistic index of 2.39.

CONCLUSION

This study supports that exposures to ambient PM_2.5 and O₃ might be important risk factors of presbyopia among old adults, and simultaneously exposure to high level of the two pollutants could intensify their individual effects.

Risk factors for ocular surface damage in Mexican patients with dry eye disease: a population-based study

PURPOSE

To analyze potential risk factors for ocular surface damage in a representative population of Mexican patients with dry eye disease (DED).

PATIENTS AND METHODS

A prospective and cross-sectional population-based epidemiologic cohort study was conducted through a survey of patients with symptoms, signs, known preexisting diagnosis, and clinical conditions related to DED. Fluorescein staining, tear break-up time (TBUT), and Oxford lissamine green staining were performed on both eyes of patients enrolled in the study.

RESULTS

A total of 2,725 surveys including 1,543 (56.6%) women and 1,182 (43.3%) men were analyzed. Most common pre-existing diagnosis included dry eye (58%), chronic blepharitis (17%), and ocular allergy (15%). More than 70% of patients had a positive fluorescein test, and this prevalence increased proportionally to the number of reasons for consultation. The same was true for gender (P<0.001) and age (P<0.0001), with women showing a strong correlation with age (R2=0.93912, P=0.001). The association between positive fluorescein staining and diagnosis was significant for dry eye (P<0.0001), Sjögren's syndrome (P<0.0001), and glaucoma (P<0.05). No significant association between TBUT and age or gender was found, but the shorter the TBUT, the larger the prevalence of fluorescein staining. Reduced TBUT was seen more frequently in patients with dry eye (57%), ocular allergy (16%), and chronic blepharitis (15%). Most patients (39%) with Oxford grades III and IV were older, complained of red eye (51.0%), foreign body sensation (47.0%), burning (46.0%), and were using eye drops (67%) and systemic medications (47%).

CONCLUSION

The Mexican profile of patients with significant ocular surface damage related to DED includes women at older ages, complaining of red eye, foreign body, and burning sensation. Diagnoses of dry eye, Sjögren's syndrome, and glaucoma were also risk factors for significant ocular surface damage, along with long-term use of preserved eyes drops and systemic medications.

Impact of environmental adaptation on tear film assessments

PURPOSE

The purpose of this study was to investigate the effect of ocular environmental adaptation on clinical tear film assessment.

METHOD

Thirty subjects (male, mean age 23±2.5) participated in this study. A number of clinical tear film tests were applied, including: fluorescein tear break-up time (FTBUT), Schirmer test and tear prism height test (TPH). The tear physiology of each subject was evaluated twice, once immediately when they arrived from the external environment, and then after 30minutes adaptation in the exam room environment.

RESULTS

The mean values were: Schirmer test A (22.1±2.99), Schirmer test B (24.2±2.63), FTBUT A (8.00±1.94), FTBUT B (9.13±2.04), TPH A (0.179±0.026) and TPH B* (0.187±0.023). Statistical testing using Wilcoxon-signed rank test showed a significant difference between the Schirmer test results measured at the different times (P=0.008). Also, the FTBUT and tear prism height test results showed significant differences between the two evaluation times, (P=0.001, 0.011, respectively) (A: tear assessed when the subject comes from the outside environment, B: tear film assessed after 30min adaptation in the clinical environment).

CONCLUSION

This study showed a significant difference between the tear film test results evaluated when the subjects were assessed immediately from the outside environment and after an adaptation time in the clinic environment. Practitioners must consider the effect of differences between external and clinical environment adaptation on clinical tear film physiology.

Effects of environment pollution on the ocular surface

The twenty-first century is fraught with dangers like climate change and pollution, which impacts human health and mortality. As levels of pollution increase, respiratory illnesses and cardiovascular ailments become more prevalent. Less understood are the eye-related complaints, which are commonly associated with increasing pollution. Affected people may complain of irritation, redness, foreign body sensation, tearing, and blurring of vision. Sources of pollution are varied, ranging from gases (such as ozone and NO₂) and particulate matter produced from traffic, to some other hazards associated with indoor environments. Mechanisms causing ocular surface disease involve toxicity, oxidative stress, and inflammation. Homeostatic mechanisms of the ocular surface may adapt to certain chronic changes in the environment, so affected people may not always be symptomatic. However there are many challenges associated with assessing effects of air pollution on eyes, as pollution is large scale and difficult to control. Persons with chronic allergic or atopic tendencies may have a pre-existing state of heightened mucosal immune response, hence they may have less tolerance for further environmental antigenic stimulation. It is beneficial to identify vulnerable people whose quality of life will be significantly impaired by environmental changes and provide counter measures in the form of protection or treatment. Better technologies in monitoring of pollutants and assessment of the eye will facilitate progress in this field.

Morphological, biochemical, and histopathological postmortem ocular indices following subchronic exposure to cadmium and/or lead in a rabbit model

Cadmium (Cd) and lead (Pb) are ubiquitous environmental pollutants. There is a dearth of information on the mutual interaction between the antemortem metal intoxication and the postmortem changes of the eye. Thus, this study aimed to follow the morphological, biochemical, histopathological ocular perturbations and the retinal DNA damage up to 8 h postmortem (PM) in Cd and/or Pb intoxicated rabbits. The animals orally received 5 mg Cd Cl₂/kg bw and/or 12.5 mg lead acetate/kg bw for 30 consecutive days. At time of death, eye pupil of different groups had a normal diameter except Pb-intoxicated group had marked myosis. After 8 h of death, different rabbit's eye corneas appeared wrinkled and covered with thin white cloud while the pupils were in the mydriatic stage. Up to 8 h PM, the individual exposure to Cd or Pb resulted in a significant elevation in GGT, urea, K, DNA damage and obvious retinal lesions. However, their co-exposure evoked an antagonistic outcome. The eye of Cd and/or Pb intoxicated rabbit showed mildly degenerated tissue of cornea and sclera and the presence of irregular eosinophilic droplets of variably size in the lens with a gradual degeneration and vacuolization in the different cell layers of retina especially ganglion up to 8 h PM. Also, by increasing post mortem interval (PMI), retinal DNA damage in Cd and/or Pb intoxicated group significantly decreased. It is concluded that Cd and/or Pb intoxication induced ocular alterations which retain the same trend in correlation with PMI as natural deaths except for the retinal DNA damage. Also, the simultaneous exposure to Cd and Pb evoked an antagonistic outcome in the eye. The findings of the current study should be taken into consideration when estimating PMI in areas with high Cd and/or Pb contamination.

Ocular surface symptoms among individuals exposed to ambient levels of traffic derived air pollution - a cross-sectional study

Background: The ocular surface is separated by a thin layer of tear film from outdoor air pollutants making individuals exposed to outdoor air pollution prone to various ocular surface disorders. The aim of this study was to determine the magnitude of ocular surface disorders symptoms among traffic police officers of Kathmandu, Nepal. Methods: Two hundred traffic police officers working at different traffic police office branches of Kathmandu, Nepal were invited to the police headquarters for eye and vision examination. Among them, 91 individuals (95% males) completed the ocular surface disease index (OSDI) questionnaire and underwent Schirmer's I tear test. Results: Symptoms of ocular surface disorders were reported by over 80% of the individuals. Approximately two fifths of the individuals (38%) reported severe symptoms.  Only 17% of the individuals' tear secretion was found to be below normal using the Schirmer's tear test.  There was no association between the OSDI score and Schirmer's tear test scores (r = 0.008, p = 0.94). A weak but significant relationship was observed between the OSDI score and job duration (r=0.21,p = 0.04). Individual exposed to outdoor air pollution for more than 10 years had higher odds of reporting ocular surface complaints as compared to those who were exposed for less than 10 years (OR = 3.94, p = 0.02). Conclusion: Ocular surface disorder symptoms are common among traffic police officers of Kathmandu, Nepal. The duration of exposure appears to significantly contribute to the increased symptoms in this vulnerable population.

Ocular surface symptoms among individuals exposed to ambient levels of traffic derived air pollution - a cross-sectional study

Background: The ocular surface is separated by a thin layer of tear film from outdoor air pollutants making individuals exposed to outdoor air pollution prone to various ocular surface disorders. The aim of this study was to determine the magnitude of ocular surface disorders symptoms among traffic police officers of Kathmandu, Nepal. Methods: Two hundred traffic police officers working at different traffic police office branches of Kathmandu, Nepal were invited to the police headquarters for eye and vision examination. Among them, 91 individuals (95% males) completed the ocular surface disease index (OSDI) questionnaire and underwent Schirmer's I tear test. Results: Symptoms of ocular surface disorders were reported by over 80% of the individuals. Approximately two-fifths of the individuals (38%) reported severe symptoms.  Only 17% of the individuals' tear secretion was found to be below normal using the Schirmer's tear test. No significant association was observed between the OSDI score and Schirmer's tear test scores (r = 0.008, p = 0.94). A weak but significant relationship was observed between the OSDI score and job duration (r=0.21,p = 0.04). Individual exposed to outdoor air pollution for more than 10 years had higher odds of reporting ocular surface complaints as compared to those who were exposed for less than 10 years (OR = 3.94, p = 0.02). Conclusion: Ocular surface disorder symptoms are common among traffic police officers of Kathmandu, Nepal. The duration of exposure appears to significantly contribute to the increased symptoms in this exposed population.

A mouse dry eye model induced by topical administration of the air pollutant particulate matter 10

AIM

To introduce a novel dry eye mouse model induced by topical administration of the air pollutant particulate matter 10 (PM₁₀).

METHOD

A total of 60 male BALB/c mice were used in this study and divided into two groups: group A (PBS eye drops, n=30) and group B (PM₁₀ eye drop group, n=30). Each treatment was dosed four times a day, every time 50ul with the concentration of 5mg/ml PM10, for 14 consecutive days in the right eye. The clinical manifestations of dry eye were measured before therapy and 4, 7 and 14days post-treatment respectively, which included the tear volume, tear break-up (BUT) time, corneal fluorescein staining, rose bengal staining, Lissamine Green staining and inflammatory index. Eye samples were collected on D14 and examined by histologic light microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), corneal cytokeration 10 (K10) immunnostaining, and tumor necrosis factor-α (TNF-α), NF-κB-p65 and NF-κB Western Blot analysis.

RESULTS

At 0d, 7d and 14d, there were no statistical changes in tear volume, BUT after treatment (P>0.05) with PBS in group A. In group B, all items showed statistical differences at each time point (P<0.05). At 14d after therapy, the fluorescein staining score of group B was higher than group A (P<0.05). The score of rose bengal staining and Lissamine Green staining in group B was also higher than that in group A (P<0.05). The number of mean layers of corneal epithelial cells in the group A was significantly lower than that in the group B (P<0.05). TEM and SEM revealed that the number of corneal epithelial microvilli were drastically reduced in group B. The number of corneal chondriosome/desmosomes was also reduced in group B by TEM. PM₁₀ induced apoptosis in the superficial and basal corneal epithelium, and leaded to abnormal differentiation and proliferation of the ocular surface with higher expression levels of K10 and reduced number of goblet cells in the conjunctival fornix in group B. PM₁₀ significantly increased the levels of TNF-α, NF-κB-p65 and NF-κB in the cornea.

CONCLUSION

PM₁₀ can damage the tear film function and cause the destruction of the structural organization of ocular surface in mice. Topical administration of PM₁₀ in mice induces ocular surface changes that are similar to those of dry eye in humans, representing a novel model of DES.

Associations of PM2.5 and Black Carbon with Hospital Emergency Room Visits during Heavy Haze Events: A Case Study in Beijing, China

In January 2013, severe haze events over northeastern China sparked substantial health concerns. This study explores the associations of fine particulate matter less than 2.5 μm (PM_2.5) and black carbon (BC) with hospital emergency room visits (ERVs) during a haze season in Beijing. During that period, daily counts of ERVs for respiratory, cardiovascular and ocular diseases were obtained from a Level-3A hospital in Beijing from 1 December 2012 to 28 February 2013, and associations of which with PM_2.5 and BC were estimated by time-stratified case-crossover analysis in single- and two-pollutant models. We found a 27.5% (95% confidence interval (CI): 13.0, 43.9%) increase in respiratory ERV (lag02), a 19.4% (95% CI: 2.5, 39.0%) increase in cardiovascular ERV (lag0), and a 12.6% (95% CI: 0.0, 26.7%) increase in ocular ERV (lag0) along with an interquartile range (IQR) increase in the PM_2.5. An IQR increase of BC was associated with 27.6% (95% CI: 9.6, 48.6%) (lag02), 18.8% (95% CI: 1.4, 39.2%) (lag0) and 11.8% (95% CI: −1.4, 26.8%) (lag0) increases for changes in these same health outcomes respectively. Estimated associations were consistent after adjusting SO₂ or NO₂ in two-pollutant models. This study provides evidence that improving air quality and reducing haze days would greatly benefit the population health.

External eye symptoms in indoor environments

Eye irritation, for example dry or irritated eyes, is generally among top three reported symptoms in office-like environments, in particular among workplaces with cognitive demanding visual display unit (VDU) work. The symptoms are especially among middle and advanced ages and particularly among women more than men. The symptoms are also among the most commonly reported complaints in the eye clinic. To be in a position to interpret the high prevalence of eye symptoms, a multidisciplinary and integrated approach is necessary that involves the external eye physiology (separate from internal eye effects), eye diseases (evaporative dry eye (DE), aqueous-deficient DE, and gland dysfunctions), and risk factors that aggravate the stability of precorneal tear film (PTF) resulting in hyperosmolarity and initiation of inflammatory reactions. Indoor environmental, occupational and personal risk factors may aggravate the PTF stability; factors such as age, contact lenses, cosmetics, diet, draft, gender, low humidity and high temperature, medication, outdoor and combustion pollutants, and VDU work. Psychological stressors may further influence the reporting behavior of eye symptoms. The impact of the risk factors may occur in a combined and exacerbating manner.

Mechanisms of housedust-induced toxicity in primary human corneal epithelial cells: Oxidative stress, proinflammatory response and mitochondrial dysfunction

Human cornea is highly susceptible to damage by dust. Continued daily exposure to housedust has been associated with increasing risks of corneal injury, however, the underlying mechanism has not been elucidated. In this study, a composite housedust sample was tested for its cytotoxicity on primary human corneal epithelial (PHCE) cells, which were exposed to dust at 5-320μg/100μL for 24h. PHCE cell viability showed a concentration-dependent toxic effect, attributing to elevated intracellular ROS. Moreover, when exposed at >20-80μg/100μL, dust-induced oxidative damage was evidenced by increased malondialdehyde and 8-hydroxy-2-deoxyguanosine (1.3-2.3-fold) and decreased antioxidative capacity (1.6-3.5-fold). Alteration of mRNA expression of antioxidant enzymes (SOD1, CAT, HO-1, TRXR1, GSTM1, GSTP1, and GPX1) and pro-inflammatory mediators (IL-1β, IL-6, IL-8, TNF-α, and MCP-1) were also observed. Furthermore, the mitochondrial transmembrane potential was dissipated from 9.2 to 82%. Our results suggested that dust-induced oxidative stress probably played a vital role in the cytotoxicity in PHCE cells, which may have contributed to dust-induced impairment of human cornea.

Pollutant exposures and health symptoms in aircrew and office workers: Is there a link?

Sensory effects in eyes and airways are common symptoms reported by aircraft crew and office workers. Neurological symptoms, such as headache, have also been reported. To assess the commonality and differences in exposures and health symptoms, a literature search of aircraft cabin and office air concentrations of non-reactive volatile organic compounds (VOCs) and ozone-initiated terpene reaction products were compiled and assessed. Data for tricresyl phosphates, in particular tri-ortho-cresyl phosphate (ToCP), were also compiled, as well as information on other risk factors such as low relative humidity. A conservative health risk assessment for eye, airway and neurological effects was undertaken based on a "worst-case scenario" which assumed a simultaneous constant exposure for 8h to identified maximum concentrations in aircraft and offices. This used guidelines and reference values for sensory irritation for eyes and upper airways and airflow limitation; a tolerable daily intake value was used for ToCP. The assessment involved the use of hazard quotients or indexes, defined as the summed ratio(s) (%) of compound concentration(s) divided by their guideline value(s). The concentration data suggest that, under the assumption of a conservative "worst-case scenario", aircraft air and office concentrations of the compounds in question are not likely to be associated with sensory symptoms in eyes and airways. This is supported by the fact that maximum concentrations are, in general, associated with infrequent incidents and brief exposures. Sensory symptoms, in particular in eyes, appear to be exacerbated by environmental and occupational conditions that differ in aircraft and offices, e.g., ozone incidents, low relative humidity, low cabin pressure, and visual display unit work. The data do not support airflow limitation effects. For ToCP, in view of the conservative approach adopted here and the rareness of reported incidents, the health risk of exposure to this compound in aircraft is considered negligible.