Molecular mechanisms of retinal toxicity induced by light and chemical damage

In recent years, important advances have been made to decipher the multiple defense mechanisms of the retina (a highly specialized sense tissue) against several extreme conditions, such as constant exposure to systemic toxins, oxidative stress, and focused light rays. These studies have importantly contributed to improving our understanding of the principles underlying various drug- and light-induced disease processes, specifically at the eye level. When the different retinal cell layer defenses are overwhelmed by various xenobiotics, environmental agents such as pollution, cigarette smoke, or excessive light exposure, particularly high-frequency blue light and ultraviolet light, a pathological process may develop. Herein, we describe the main aspects of the structure and function of the retina in connection to some of the most relevant mechanisms which may generate retinal toxicity, and possible alternatives to counteract these effects. Furthermore, we summarize current knowledge about light-induced retinal toxicity as well as the effects of different natural and synthetic compounds on the molecular mechanisms underlying toxicity in the retina. Finally, the potential approaches undertaken to counteract these toxic effects, i.e., polyphenols and others, are discussed.