The Ocular Surface as a Target of Air Pollution

Abstract

The health effects triggered by air pollution exposure cause great concern worldwide. Particulate matter (PM) is a critical component of polluted air and has been pointed out as the main responsible for the negative impact on human health associated with air pollution exposure. The ocular surface is constantly exposed to the environment, only separated by the tear film. For this reason, it has become increasingly relevant as a target of air pollutants. Moreover, it has been reported that people living in highly polluted areas, such as populated urban centers, show eye discomfort symptoms, as well as aggravation of preexisting ocular diseases. These effects are likely a result of vascular and neurotoxic mechanisms, as well as a consequence of changes in the intraocular fluid redox homeostasis that communicate the different eye structures. In this sense, in vivo and in vitro studies have described the deleterious effects of air pollutants on the cornea and the conjunctiva, suggesting that PM alters the ocular surface by inducing an imbalance in redox metabolism, intracellular signalling, and pro-inflammatory mediators’ release. In this context, oxidative damage to macromolecules occurs, leading to morphological changes that can affect tissue function. In this chapter, we will review the main effects observed in the ocular surface triggered by PM exposure, highlighting the role of oxidative stress and inflammation in the cornea and the conjunctiva.