SOME CAUSES OF VISUAL IMPAIRMENT

Macular Degeneration
Reproduced courtesy of The Macular Degeneration Foundation

Adult MD

Adult macular degeneration is traditionally described as that form of the disease that affects individuals over the age of 55 years. However we have recently discovered that a significant number of these individuals may have a major genetic component that contributes to the disease.

What does macular degeneration do to your vision?
Your retina contains an extraordinary photosensitive array of cells that line the back of your eye. The light falling onto these cells in the retina is transformed into electrical signals rich which are transmitted to the brain centers that process and interpret them.

The most concentrated collection of photosensitive cells in your retina including those that enable critical color and fine detail vision are found in the Bulls-Eye center zone in an area called the macula.

Macular degeneration is the imprecise historical name given to that group of diseases that causes sight-sensing cells in the macular zone of the retina to malfunction or lose function and results in debilitating loss of vital central or detail vision.  Because the brain cleverly learns to compensate and fill in the missing part of the picture in early cases with spotty macular cell damage or dysfunction, most people only present to their ophthalmologist when disease is fairly advanced. Compared to the huge numbers of people affected (over 12 million), research efforts towards discovery of cause and cure by government, public and private institutions are inappropriately small.

What are the Symptoms of Macular Degeneration?
Macular degeneration can cause different symptoms in different people. Sometimes only one eye loses vision while the other eye continues to see well for many years. The condition may be hardly noticeable in its early stages. But when both eyes are affected, reading and closeup work can become difficult.  See: Seeing with MD.

Who gets adult macular degeneration?
If you have been diagnosed as having an adult macular degeneration you are in good company. Another case of adult macular degeneration is diagnosed every three minutes in the United States of America. One in six Americans between the ages 55 and 64 be affected while one in four Americans between 64 and 74 will be smitten. Over age 75 one in three of your peers will be affected. Each year 1.2 million of the estimated 12 million people with macular degeneration will suffer severe central vision loss. Each year 200,000 individuals will lose all central vision in one or both eyes.

While the causes of macular degeneration are unknown some tantalizing clues have become available. Genetics researchers supported in part by the Macular Degeneration Foundation have recently discovered a group of set of genes termed ABCR.

Possession of these genes may increase the likelihood of an individual developing macular degeneration by approximately 30 percent. However, most macular diseases have a complex genetic makeup compared with simple single gene-causation diseases. In most individuals macular degeneration is likely due to a combination of environmental and genetic factors combining to cause damage and disease.

Genetic typing of patients with macular degeneration is likely to assume more and more importance in the future. It will enable ophthalmologists to identify high-risk individuals and to better understand the relationships between genetic defects, the appearance of the macula and how the disease progresses. This information will hopefully provide scientists with some of the tools they need to develop therapies that can prevent, slow and even arrest the progression of the disease.

What should you or loved one do if you have macular degeneration? First it is important to modify those environmental risk factors that we know about. You should:

1. Detail a low-fat, low cholesterol diet.

2. If you are a postmenopausal or among you should together with your physician consider estrogen replacement therapy because this has a favorable impact upon cholesterol lipid levels that play a role in worsening the disease.

3. Wear sunglasses outdoors whenever possible. Amounts do not protect against ultraviolet light.

4. Try to consume at least two servings of leafy dark green vegetables per day.

5. Do not smoke and avoid exposure to secondhand smoke from others.

6. Eat food and or supplements rich in vitamin E, C and Lutein. Lutein is plant antioxidant found in high quanties in spinach, kale and other leafy dark green vegetables Some emerging theories about what may have a role in causing or worsening macular degeneration are as follows:

 

A. The macular contains many highly active and sensitive photoreceptors that require and consume a great deal of energy. Generating this energy requires a constant and rich supply of oxygen, nutrients and ions. Consequently, the macular has one of the highest rate so blood flow through its supply vessels. Anything that interferes with this necessary rich blood supply can cause the macula to malfunctioning and possibly become diseased.

B. Smoking can reduce this vital blood supply on a contributing to narrowing the blood vessels and thickening the blood as it does in other parts of the body such as the heart and brain where this process contributes to heart attacks and strokes respectively.

C. A high-fat high cholesterol diet can lead to fatty plaque deposition in the macular vessels hampering blood flow. 4. Shortage of antioxidants may also increase the tendency for fatty deposits to stick to blood vessel walls.