Understanding Oxidative Stress
Oxidative stress is a broad, well-understood platform for degenerative diseases and the aging process. It occurs when a cell is incapable of maintaining a biologically-balanced level of Reactive Oxygen Species (ROS). ROS include oxygen ions, free radicals and peroxides (both inorganic and organic). They are generally very small molecules and are highly reactive due to the presence of unpaired valence shell electrons. These molecules react with other key organic substrates such as lipids, proteins and DNA and often cause instability in cells by disturbing normal cell function. This is the basis for the oxidative stress disease pathology.
During times of increased environmental risks (e.g., ultraviolet radiation from sunlight, smoking, alcohol consumption and age); ROS levels can increase dramatically; resulting in significant damage to cell structures. Thus, oxidative damage is characteristic of aging and diseases of old age. Not only does it lead to the development of senile cataract, it is also a well-known and accepted pathogenesis of many other types of human diseases, including diabetes, cardiovascular disease, and neurological diseases, among others.
Oxidative Stress in Ocular Conditions – Free metal ions play a key role in catalyzing oxidative stress and causing tissue damage in ocular conditions. In particular, free iron ions (Fe⁺⁺ and Fe⁺⁺⁺) become more abundant with age and are the catalyst for the development of ROS. In addition, metal ions (typically calcium; i.e., Ca⁺⁺) act as a binder for damaged lipids and proteins, causing aggregations and even further tissue damage; the basis for most degenerative ocular diseases.
For example, metallo-lipid/protein aggregates have been implicated in cataracts (where they cause opacities of the lens), in glaucoma (where the aggregates block the natural drainage mechanisms of the eye), and in asteroid hyalosis (where they form asteroid bodies which are suspended throughout the vitreous humor). While these lipid/protein aggregates may be different in each disease, they are all characterized by their properties of being bound by Ca⁺⁺.