Thursday, 14 November 2013

One of the main causes of sight loss in the world is Age Related Macular Degeneration (AMD). There are two types of macular degeneration, wet and dry. Wet progresses more rapidly than dry and can be treated using certain drugs.  For many years scientists have searched for a cure to dry AMD but without much success. The following information may help to explain the current thinking on prevention.
George Torrey, Ph.D., a graduate of Brown (‘61), Harvard (‘62) and the Univ. of Connecticut (‘68), writes for the AMDF Newsletter and the AMDF Web site. Both his parents suffered from macular degeneration.
Consumption of fruits and vegetables containing two carotenoid pigments may be linked to a reduced risk for age-related macular degeneration, the leading cause of vision loss in people over the age of 55. According to research, lutein and zeaxanthin comprise a component of the central region of the retina and may play a role in some aspects of visual acuity. Increasing the concentration of these pigments in the eye may prevent the devastating vision loss caused by age-related macular degeneration.
Increasing macular pigment density may slow, or possibly even reverse, the progression of age-related macular degeneration.
Carotenoids are phytochemicals (chemicals found in plants) commonly found in certain fruits and vegetables that provide the red, orange and yellow colours of these foods. Lutein and zeaxanthin are found primarly in broccoli, corn, squash and dark green leafy vegetables like spinach and kale.
Lutein and zeaxanthin are concentrated in the fovea, the central region of the retina, in a spot known as the macula lutea, or yellow spot. The macula helps produce the sharp central vision needed for activities like reading, sewing and driving.
For the vast majority of those with age-related macular degeneration (AMD), there is no known cure or treatment. Symptoms of AMD include blurred or fuzzy vision; the illusion that straight lines, such as sentences on a page, are wavy; and the appearance of a dark or empty area in the center of vision. Risk factors for the disease include cigarette smoking and family history of AMD. Exposure to sunlight/UV, having light coloured irises, and even being a woman appear to be additional risk factors.
According to an article in The British Journal of Ophthalmology(2.) eating green leafy vegetables, which are rich in lutein and zeaxanthin, may decrease the risk for age-related macular degeneration. The goal of this study was to analyse various fruits and vegetables to establish which ones contain lutein and/or zeaxanthin and can serve as possible dietary supplements for these carotenoids.
Egg yolk and yellow corn contain the highest mole percentage (% of total) of lutein and zeaxanthin (more than 85% of the total carotenoids). Yellow corn was the vegetable with the highest quantity of lutein (60% of total) and orange pepper was the vegetable with the highest amount of zeaxanthin (37% of total). Substantial amounts of lutein and zeaxanthin (30-50%) were also present in kiwi fruit, grapes, spinach, orange juice, courgette, and different kinds of squash. The results show that there are fruits and vegetables of various colours with a relatively high content of lutein and zeaxanthin.
Most of the dark green leafy vegetables, previously recommended for a higher intake of lutein and zeaxanthin, have a 15-47% of lutein, but a very low content (0-3%) of zeaxanthin. This study shows that fruits and vegetables of various colours can be consumed to increase dietary intake of lutein and zeaxanthin.
Dr. Johanna M. Seddon and her associates at Harvard University(3.) found that 6 mg per day of lutein lead to a 43 percent lower risk for macular degeneration. Half a cup of cooked kale contains 10.3 mg of lutein while half of a cup of cooked spinach provides 6.3 mg.
The Schepens Eye Research Institute 1998 study concluded that vision loss associated with aging maybe preventable - even reversible - through improved nutrition. Although visual sensitivity decreases with age, this process need not be inevitable.