A review of 41 studies involving millions of people across East Asia and the United Kingdom suggests that air pollution exposure is associated with glaucoma and cataracts. Presented in September at a European eye-surgery congress in London, the findings point to environmental exposure as a factor alongside aging, which increases susceptibility to both conditions. Glaucoma damages the optic nerve, potentially causing irreversible vision loss, while cataracts cloud the eye's lens and can eventually cause blindness.
The clearest associations involved PM2.5, airborne particles measuring no more than 2.5 micrometers. Most studies estimated long-term exposure near participants' homes through monitoring networks, satellite data, or computer models. Associations involving other pollutants were less consistent, as was the evidence linking pollution to age-related macular degeneration, a condition affecting detailed central vision. Because the studies were observational, their findings establish associations rather than demonstrate that pollution causes these diseases.
Researchers have proposed biological pathways that could help explain the connection. Fine particles can enter the body and trigger oxidative stress, in which damaging molecules overwhelm natural defenses, as well as persistent low-level inflammation. These processes may harm proteins that keep the lens transparent or damage nerve cells involved in vision. The eye's surface also remains directly exposed to outdoor air. Supporting experiments found elevated eye pressure in mice exposed to PM2.5 for nine months, while laboratory-grown human retinal tissue showed disrupted cell development and increased cell death after exposure. How these mechanisms interact in people remains uncertain.
