May 24, 2005.
New Straits Times (Malaysia).
LEONG accepts that his vision will diminish one day; his father became blind at the age of 65. He has been diagnosed with retinitis pigmentosa, an inherited eye disease that affects the retina.
The retina sits at the back surface inside the eye and directly opposite the lens. It contains millions of photosensitive cells called rods and cones that differentiate intensities of light and colours. When light hits the rods or cones, a biochemical reaction occurs, which initiates the transmission of signals along nerve cells to the brain, thus translating the image we see.
Retinitis pigmentosa (RP) causes the degeneration of rod cells and cone cells resulting in progressive vision loss. Rod cells are concentrated along the outer edge of the retina, which are responsible for our side or peripheral vision. Rod cells also help us to see in a poorly lit environment. Cone cells, which help us see colours, are concentrated in the centre of the retina also known as the macula and they provide the central vision.
There are several forms of retinitis pigmentosa and usually the signs and symptoms often first appear in childhood and develop into severe visual problems by early adulthood. Degeneration of the rod cells result in night blindness and the inability to adjust even to dimly lit environment. As the disease progresses and more rod cells degenerate, patients lose their peripheral vision. Another form of retinitis pigmentosa sometimes called cone-rod dystrophy, affects the cone cells resulting in loss of central vision and colour perception. This group of eye disorders is rather rare and it is estimated that the incidence is approximately one in 4,000.
There is no effective treatment for this condition. The disorder will continue to progress slowly and not all who suffer with retinitis pigmentosa will go completely blind though their vision will be severely hampered. Some studies indicated that treatment with antioxidants such as vitamin A may slow the progression of retinitis pigmentosa. Vitamin A is a basic nutrient required by the rods and cones to aid in responding to light and for the transmission of messages to the brain. Deficiency in vitamin A is associated with night blindness and the surface area of eye to become rough and opaque which leads to distorted and impaired vision.
A recent comprehensive epidemiologic study concluded that very high daily doses of vitamin A palmitate (15,000 IU per day) slow the progress of retinitis pigmentosa by about 2 per cent per year. Researchers however warn that the effects are modest and must be weighed against the uncertain risk of long-term adverse effects from large chronic doses of vitamin A.
A safer form of administering Vitamin A is in the form of beta-carotene. Beta-carotene is a provitamin A compound, as it is converted in the body into retinol, the active form of vitamin A. Beta-carotene is found in green, yellow and orange vegetables, fruits and herbs such as eyebright which is traditionally used for eye health. Antioxidants destroy free radicals, which are believed to be associated with many of the degenerative changes in age-related eye health.
Among all the foods, plant sources contain the most varied antioxidants. It is a known fact that a rich plant-based diet reduces the developmental risk of several chronic diseases due to their antioxidant protection. Researchers in Norway screened a variety of dietary plants used worldwide that includes various fruits, berries, vegetables, cereals, nuts and pulses and found that berries such as bilberries were exceptionally high in antioxidants.
The health of the eye depends on the availability and balance of nutrients and a well-balanced diet high in plant foods is highly recommended. The use of sunglasses to protect the retina from ultraviolet light is also encouraged as this habitual practice may have a vision-preserving effect. Regular visits to your eye care specialist are important to monitor the progression of the condition.
Yam Cher Seng is a pharmacist who is actively involved in the dissemination of information on natural healthcare and holistic therapies. The writer can be contacted at firstname.lastname@example.org
Source URL: http://www.nst.com.my/Current_News/NST/Tuesday/BodySoul/20050523161442/Article/indexb_html
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