Cataracts and age-related macular degeneration are the main causes of blindness and both are age-related. Both diseases are thought to be a direct result of accumulated oxidative damage. Research is now looking at the connection between the free radical theory of ageing, with cell damage being caused by reactive oxygen species (ROS). Sources of ROS are known to be solar radiation, biomass fuels and smoking. There is also strong evidence of links between smoking and cataracts, moderate evidence of a link between sunlight and cataracts and some suggestion of links between biomass fuels and cataracts.
What are Free Radicals?
Various reactive species are free radicals and have free-floating electrons, which can donate the oxygen to other substances, thereby changing their structure. Free radicals are derived from natural metabolic processes in the body, from the respiratory process, inflammation and exercise or from external sources such as exposure to ozone, x-rays, smoking, ultraviolet light, pollution and chemicals.
When electrons become unhinged in any of these processes they roam the body and can wreak havoc on molecules they attach to. Their activity has been likened to letting a bachelor attend a couples' dance. He will cut in for a dance, leaving another bachelor without a partner and soon the break up of couples has spread across the dance floor.
In the same way, if free radicals are not inactivated, their chemical reactivity can damage other molecules. This destructive effect on proteins is thought to play a part in causing cataracts, among other diseases.
Counteracting Free Radical Damage
The body has several ways it can counter the damage of free radicals, including the production of enzymes that decrease concentrations of the most harmful oxidants in the tissues. Selenium, copper, manganese and zinc are necessary for the body to produce these enzymes and lack of them will mean action against the harmful free radicals may be impaired.
Antioxidants are molecules that are strong enough to neutralize free radicals in the body. Some antioxidants are found in the body, some are produced during the metabolic process and others are found in the diet. The best known are vitamin E, vitamin C and carotenoids, hence their vital importance to overall good health.
The balance between the production of free radicals and the antioxidant defenses are therefore vital. A lack of antioxidants can create a situation of oxidative stress in the body, which is thought to cause chronic damage.
Antioxidants and Eye Disorders
Oxidative processes are now thought to be a cause of cataracts and maculopathy, an age-related disorder of the retina. In cataracts, oxidation induced by exposure to ultraviolet rays (sunlight) is thought to cause damage to the lens, making it cloudy and opaque. Vitamin E, vitamin C and carotids are all proven to decrease the risk of cataract and slow down the lens from becoming cloudy, limiting vision. How exactly these antioxidants work is still being studied and not all studies are showing consistent results.
Exposure to light is also associated with age-related macular degeneration and while vitamin E has not so far been found to make a difference, carotenoids have been found to decrease the risk of this disorder.
No doubt future studies will reveal greater insight into the prevention and treatment of eye disease, but in the meantime there is nothing to be lost and everything to be gained from including antioxidants in your daily supplement intake.