Large systematic review finds PM2.5 exposure associated with increased glaucoma and cataract risk, with the highest pollution exposure linked to up to 70% higher odds of glaucoma
Long-term exposure to higher levels of air pollution may be associated with an increased risk of glaucoma and cataract, according to a large systematic review and meta-analysis presented at the 44th Congress of the European Society of Cataract and Refractive Surgeons (ESCRS).
The analysis included 41 observational studies involving millions of people, with data from East Asia and the United Kingdom. Researchers evaluated exposure to several major air pollutants, including fine particulate matter (PM2.5), PM10, nitrogen dioxide, sulphur dioxide, ozone, and carbon monoxide, and examined their associations with glaucoma, cataract, and age-related macular degeneration.
The strongest and most consistent associations were observed with fine particulate matter (PM2.5). People living in areas with the highest PM2.5 exposure had up to 70% higher odds of glaucoma compared with those in areas with the lowest exposure. Higher PM2.5 exposure was also consistently associated with increased cataract risk.
Study Examines Air Pollution and Major Eye Diseases
The research was presented by Dr Ahmed Alnabihi from King Khaled Eye Specialist Hospital and Research Center in Riyadh, Saudi Arabia.
Researchers conducted a systematic review and meta-analysis to bring together available epidemiological evidence on the relationship between air pollution and age-related eye diseases.
The analysis considered particulate matter, nitrogen dioxide, sulphur dioxide, ozone, and carbon monoxide. These exposure levels were compared with diagnoses of glaucoma, cataract, and age-related macular degeneration.
According to the researchers, evidence for age-related macular degeneration was less consistent, while associations involving several other pollutants were weaker or mixed.
PM2.5 Shows Strongest Association With Glaucoma
Fine particulate matter emerged as the clearest pollution-related factor associated with eye disease.
The analysis found that for each meaningful increase in PM2.5 exposure, glaucoma risk increased by approximately 8%. When the highest and lowest exposure groups were compared, people in the most polluted areas had up to 70% higher odds of glaucoma.
The pooled analysis reported an odds ratio of 1.08 for glaucoma per interquartile-range increase in PM2.5, while the highest-versus-lowest exposure comparison showed an odds ratio of 1.70.
Cataract Risk Also Increased With Pollution Exposure
Higher PM2.5 exposure was also associated with an increased risk of cataract.
Researchers estimated that each meaningful increase in fine particulate exposure was associated with approximately a 4% increase in cataract risk. The analysis showed a consistent relationship between greater pollution exposure and cataract risk.
Cataract occurs when the eye’s lens becomes cloudy and can lead to blurred vision and loss of sight. According to the ESCRS, cataract affects approximately 94 million people worldwide.
How Could Air Pollution Affect the Eyes?
Researchers suggest that fine particulate matter may contribute to inflammation and oxidative stress, biological processes that could affect ocular tissues after prolonged exposure.
Long-term exposure may potentially damage the optic nerve, which is central to the development of glaucoma, or affect the lens, which is involved in cataract formation.
The eye is also directly exposed to the surrounding environment. Its ocular surface, including the tear film, conjunctiva, and cornea, comes into direct contact with outdoor air.
However, the researchers emphasized that the available evidence does not establish that air pollution directly causes glaucoma or cataract. The underlying studies were observational, meaning they can identify associations but cannot prove causation. Further research is required to clarify the biological mechanisms and long-term effects.
Evidence for Macular Degeneration Less Consistent
The researchers also examined age-related macular degeneration (AMD).
Compared with the findings for glaucoma and cataract, the evidence linking air pollution with AMD was less consistent. Some research supported an association, while the overall evidence was not as clear.
The analysis also found weaker or mixed associations for pollutants such as nitrogen dioxide and ozone.
Researchers Call for Further Eye Health Studies
The researchers said additional studies are needed, particularly in regions experiencing high levels of air pollution.
Because the current analysis combined observational studies, future research may help determine whether reducing exposure to specific pollutants can lower the risk of eye disease and clarify which populations may be particularly vulnerable.
The findings nevertheless add ocular health to the broader range of potential health concerns associated with long-term air pollution exposure.
Important Highlights
- A systematic review and meta-analysis of 41 observational studies examined the relationship between air pollution and major eye diseases.
- Higher PM2.5 exposure was associated with increased risks of glaucoma and cataract.
- People in the highest pollution exposure groups had up to 70% higher odds of glaucoma compared with those in the lowest exposure groups.
- Each meaningful increase in PM2.5 exposure was associated with approximately an 8% increase in glaucoma risk and a 4% increase in cataract risk.
- Evidence linking air pollution with age-related macular degeneration was less consistent.
- Because the underlying studies were observational, the findings demonstrate associations rather than proving that air pollution directly causes glaucoma or cataract.
