Published online Aug 12, 2014. doi: 10.5318/wjo.v4.i3.29
Revised: May 23, 2014
Accepted: June 10, 2014
Published online: August 12, 2014
A number of studies have shown that oxidative stress can be harmful for the retina. The real causal circumstances that lead to degenerative diseases like age related macular degeneration remain obscure. Whether light induced radical stress is a direct interaction of light with photoreceptors or a secondary mechanism within the pigment epithelium or choroid is in discussion. Among the molecular mechanisms involved are production of reactive oxygen species (ROS), secondary lipid peroxidation, protein oxidation and DNA-damage. The initial trigger to write this review was first a recent finding of our group that the photoreceptor outer segments produce great amounts of ROS and second the detection of ectopic enzymes of the respiratory chain localized there - in addition to the hitherto known ROS sources like the visual pigments with their intermediates and the photoreceptor mitochondria harbouring the respiratory chain.
Core tip: The role of blue light and oxidative stress in the pathogenesis of retinal degenerative diseases like age related macular degeneration is still under debate. Recent studies including ours have demonstrated that all molecules of the respiratory chain are present in the outer segment of the photoreceptors-also being the source of reactive oxygen species-even more than the reactive oxygen species production in inner segment mitochondria. These two new findings have also important implications for many degenerative diseases of the retina. In this respect we revisited the literature regarding the photoreceptor reactions after blue light and radical stress.