Ambient black carbon exposure may be a risk factor for increased intraocular pressure (IOP) in individuals susceptible to other biological oxidative stressors. The results of a recent study may point to the potential need to broaden the factors considered when evaluating and managing elevated IOP.

Researchers investigated the association of long-term ambient black carbon (a byproduct of combustion processes) exposure with intraocular pressure in community-dwelling older adults. The effort used data from the Normative Aging Study of the US Department of Veterans Affairs, an analysis that included 419 older men based in New England with a total of 911 follow-up visits. Of those exams, 57.1% had a high endothelial function allelic risk score, 70.7% had a high metal-processing allelic risk score and 68.4% had a high oxidative stress allelic risk score.  

They found the association of black carbon with IOP was greater in individuals with a high oxidative stress allelic score. When patients with high or low oxidative stress allelic risk scores were compared, the study detected a moderate difference in mean IOP (0.73mm Hg) for an increase in one year of black carbon exposure.

The team is interested in whether their findings persist in more diverse populations experiencing greater pollution and in study designs that can demonstrate causality. If future studies substantiate their association, the researchers suggest that integrated initiatives—combining environmental improvement, socioeconomic outreach and targeted pharmaceutical interventions—may prove useful for future policy or public health initiatives aimed at addressing eye disease.

Nwanaji-Enwerem JC, Wang W, Nwanaji-Enwerem O, et al. Association of long-term ambient black carbon exposure and oxidative stress allelic variants with intraocular pressure in older men. JAMA Ophthalmol. November 8, 2018. [Epub ahead of print].