Air pollutants may cause eye disease
Outdoor and indoor air pollutants may contribute to the development of eye disease, according to a review published inInternational Journal of Environmental Research and Public Health.
“Outdoor and indoor air pollution is derived from different sources and can cause different eye diseases,”Chia-Ching Lin,of the department of ophthalmology at Kaohsiung Municipal Siaogang Hospital, Taiwan, and colleagues wrote. “Ocular surface irrigation, conjunctivitis and dry eye disease are the most direct results of air pollution. However, chronic inflammation, oxidative stress and toxicity resulting from air pollution can further cause cataracts, glaucoma, uveitis, retinal layer thinning, macular degeneration and diabetic retinopathy.”
In a literature review, Lin and colleagues searched the PubMed and Medline databases and Google Scholar for information published between Jan. 1, 1990, and July 31, 2021, on ocular diseases linked to air pollution. Studies published within the last 5 years were favored to highlight recent evidence.
Twenty-eight review papers and 83 research papers, including both human and animal studies, were analyzed, and conjunctivitis was the ophthalmologic disorder most associated with air pollution.
Additionally, outdoor pollutants were associated with ocular surface disease, glaucoma and retinopathy, while indoor pollutants were associated with ocular surface disease, glaucoma, retinopathy, cataract and uveitis.
Ozone, nitrogen dioxide, sulfur dioxide, lead, carbon monoxide and particulate matter (PM), which can be further identified as coarse, fine and ultrafine, were observed outdoor air pollutants that contributed to various eye diseases.
Studies in the review found that exposure to high levels of fine PM was related to a diagnosis of glaucoma, and early contact with coarse PM increased the chances of glaucoma in childhood.
Retinopathy and maculopathy were found to be a result of outdoor air pollution because of its ability to induce oxidative stress, activate inflammatory pathways and increase coagulation. Additionally, one study found that fine PM and nitrogen oxide exposure increased the possibility for developing myopic macular diseases.
Exposure to indoor tobacco smoking was shown to affect the ocular surface and cause itchiness, redness and irritation. This pollutant type also increased fine PM levels in homes and was significantly associated with cataract formation, according to the review.
Additionally, Lin and colleagues observed that the association between current cigarette smoking and primary open-angle glaucoma was stronger than it was in past smoking, and heavy smoking could mean a higher risk for developing glaucoma.
Studies in the review found that cigarette smoking may be linked to uveitis, more so in noninfectious uveitis.
Tobacco smoking was also linked to age-related macular degeneration, polypoidal choroidal vasculopathy and inflamed cystoid macular edema. Children whose mothers smoked were found to be at risk for stage 3 and 4 retinopathy of prematurity and having a thinner retinal nerve fiber layer.
“Further research on the effects of air pollution on retinal ganglion cells and the chorioretinal vasculature may help identify the underlying pathological mechanisms,” Lin and colleagues wrote. “In addition, further research on the association between air pollutants and ophthalmological disorders is needed to improve the understanding of exposure patterns and ocular effects. Such studies will help determine the long-term impacts of air pollutants on the eye, which are currently unknown.”