Oxidative Stress Induced Damage of the Human Retina: Overview of Mechanisms and Preventional Strategies

Abstract

A number of studies have shown that excessive visible light or a special wavelength (blue light) can induce damage to photoreceptor and retinal pigment epithelial cells of the retina, inducing apoptosis. Most of these studies were performed in experimental animal models. However, the mechanisms which lead to damage and subsequently to degenerative diseases like age related macular degeneration (ARMD) remain still unclear. Whether direct interaction of light with retinal cells or a secondary mechanism of transport or circulation of the retinal pigment epithelium or the choroid causes this retinal damage is currently under debate. Cellular mechanisms involved are lipid peroxidation, production of reactive oxygen species (ROS), apoptosis, DNA-damage and others. Clinical or epidemiological studies on this topic are rare and publications about light damage of retinal cells in vivo are difficult to achieve. Nevertheless, the clinical practise to implant yellow artificial lenses during cataract surgery is a common practise. These implants are expected to prevent blue light damage to the aging retina. We will address the fact that numerous basic scientific publications point to a rationale for this practice, although it is often difficult to derive clear-cut evidence from clinical epidemiological studies for the preventive use of yellow tinted artificial lenses. We refer to studies showing that the shortwave part of the visible spectrum of light can be harmful to the retina, especially to the macula and optic nerve. For this, we have screened the literature for the major sources of radical production and for the targets of oxidative stress after impingement of “blue light” on the retina. Furthermore, we can show that many studies in cell and molecular biology, animal experiments and first clinical trials point to a preferential use of yellow tinted lenses especially in the elderly and ARMD patients. As in several other fields, so too in this field does “cell biological knowledge” exceed clinical knowledge. Thus, prevention strategies and therapies are still missing. It is important that clinicians should become more aware of this topic so that more informed treatments decisions can be made.