Figure 1.

Redox homeostasis in the eye. A homeostatic balance of antioxidants and reactive oxygen species (ROS) is required for the healthy functioning of ocular tissues. An imbalance of antioxidants (AOX) and ROS through either the depletion of antioxidants or excessive ROS accumulation will result in oxidative stress and drive subsequent disease progression. Antioxidants are categorized as either enzymatic or non-enzymatic. ROS can be derived from either endogenous or exogenous sources. Examples of heavy metals include lead (Pb), arsenic (As), and mercury (Hg).