Glaucoma is Associated with Greater Exposure to Polluted Air

by | Dec 30, 2019 | 2019, Environmental Health, Eye Health, Pollution

Written by Joyce Smith, BS.  Study validates that long-term exposure to fine particulate matter pollution increases the risk of glaucoma.

Environmental HealthAmbient air pollution contributes greatly to our global disease burden 1,2 and is associated with pulmonary, cardiovascular, Alzheimer’s and Parkinson’s diseases, and even stroke 2,3. Of all air pollutants, long-term exposure to particulate matter larger than 2.5um in aerodynamic diameter (PM2.5) is one of the strongest and most consistent predictors of mortality 2.

Glaucoma is a common, age-related degenerative neuropathy and a leading cause of global blindness. According to the International Agency for the Prevention of Blindness, the term ‘glaucoma’ refers to a neurodegenerative disease that involves a group of conditions that can be classified in a variety of ways, all of which are characterized by optic nerve damage and visual field loss.  In England approximately 480,000 people have chronic, open-angle glaucoma that most commonly results in increased fluid build-up in the eye, causing damage to the optic nerve that connects the eye to the brain. Glaucoma is reported to be 50% more prevalent in urban populations 4, and 90% of the world’s population is exposed to air pollution above the recommended limits of the World Health Organization,  yet few studies have addressed the association between glaucoma and polluted air.

In this study 5, researchers analyzed questionnaire data, ophthalmic measures, and ambient residential area air quality data for 111,370 UK Biobank participants. Particulate matter with an aerodynamic diameter < 2.5 lm (PM2.5) was selected as the air quality exposure of interest. Eye measures included self-reported glaucoma, intraocular pressure (IOP), and average thickness of macular ganglion cell–inner plexiform layer (GCIPL). Assessing the inner structure of the retina, including the GCIPL that becomes thinner in patients with glaucoma, is a reliable measure for diagnosing glaucoma. Lastly, researchers determined whether there were any associations between PM2.5 concentration and self-reported glaucoma, IOP, and GCIPL.

  • The research team found that study participants residing in neighborhoods with higher amounts of fine particulate matter pollution (the most polluted 25% of areas) were at least 6% more likely to report having glaucoma than those in the least-polluted areas (odds ratio ¼ 1.06, 95% confidence interval [CI] ¼ 1.01–1.12, per interquartile range [IQR] increase P ¼ 0.02).
  • They were also significantly more likely to have a thinner retina, one of the changes typical of glaucoma progression. Higher PM5 concentration was also associated with thinner GCIPL (b ¼ 0.56 lm, 95% CI ¼ 0.63 to 0.49, per IQR increase, P ¼ 1.2 3 10 53).
  • There was no clinically relevant relationship between air pollution (PM5 concentration) and IOP, suggesting that air pollution may affect glaucoma risk through a different mechanism.

The use of participants’ home address for air pollution estimation, which failed to account for individual activities, indoor air pollution, and workplace exposure 6, in addition to self-reported glaucoma from questionnaires, may have increased the risk of misclassification bias.

While the association is not causal, researchers recommend future studies to determine whether air pollution does indeed cause glaucoma, and to determine potential strategies such as lifestyle modification, treatment, or policy changes that could potentially reduce air pollution exposure and mitigate health risks.

Source: Chua, Sharon YL, Anthony P. Khawaja, James Morgan, Nicholas Strouthidis, Charles Reisman, Andrew D. Dick, Peng T. Khaw, Praveen J. Patel, and Paul J. Foster. “The Relationship Between Ambient Atmospheric Fine Particulate Matter (PM2. 5) and Glaucoma in a Large Community Cohort.” Investigative ophthalmology & visual science 60, no. 14 (2019): 4915-4923.

© 2019 The Authors. This work is licensed under a Creative Commons Attribution 4.0 International License.

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Posted December 30, 2019.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

  1. WHO. Air quality guidelines – global update 2005. 2019; https://www.who.int/phe/health_topics/outdoorair/outdoorair_aqg/en/. Accessed February 20, 2019.
  2. Cohen AJ, Brauer M, Burnett R, et al. Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015. The Lancet. 2017;389(10082):1907-1918.
  3. Block ML, Calderón-Garcidueñas L. Air pollution: mechanisms of neuroinflammation and CNS disease. Trends in neurosciences. 2009;32(9):506-516.
  4. Vijaya L, George R, Baskaran M, et al. Prevalence of primary open-angle glaucoma in an urban south Indian population and comparison with a rural population: the Chennai Glaucoma Study. Ophthalmology. 2008;115(4):648-654. e641.
  5. Chua SY, Khawaja AP, Morgan J, et al. The Relationship Between Ambient Atmospheric Fine Particulate Matter (PM2. 5) and Glaucoma in a Large Community Cohort. Investigative ophthalmology & visual science. 2019;60(14):4915-4923.
  6. Izzotti A, Bagnis A, Saccà SC. The role of oxidative stress in glaucoma. Mutation Research/Reviews in Mutation Research. 2006;612(2):105-114.