The macula in the eye renders a clear central vision. Macular Degeneration is a serious medical condition that usually affects the elderly. It results in a loss of vision in the center of the visual field(the macula) because of the damage to the retina and causes the breakdown of the macula located in the retina. It affects around 30-50 million people globally. Scientific evidence shows that genes may play a role in the development of nearly three out of four cases of this devastating eye disease. Occurring after the age of 50, it leads to a progressive loss of central vision, which is needed for activities like reading, recognizing faces and driving. It occurs in either dry or wet forms and is often considered an incurable eye disease. Although enough peripheral vision remains to allow other activities of daily life, it never causes complete blindness. It can rob the individual of all but the outermost peripheral vision, leaving only dim images or holes at the center of vision. The injury to the macula in the center of the retina can impair the ability to see straight ahead and clearly.
It comes in two forms, i.e. in the dry (non-exudative) form, cellular debris called drusen accumulates between the retina and the choroid, causing atrophy and scarring to the retina. The cells of the macula tend to break down in the dry AMD that in turn produces blurred vision and blank spots in the eye’s central vision. In the wet (exudative) form, which is more severe, blood vessels grow up from the choroid behind the retina which can leak exudate and fluid and also cause hemorrhaging. The delicate new blood vessels begin to grow beneath the retina. These blood vessels leak blood and fluid into the macula and can cause scarring. It can be treated with laser coagulation, and more commonly with medication that stops and sometimes reverses the growth of blood vessels.
Risk Factors for Age-Related Macular Degeneration – Although macular degeneration definitely has a strong genetic component, its development is mostly due to a combination of factors, including:
- Age – The number one risk factor is age. The fact at one-third of adults over 75 are affected by AMD is a proof.
- Smoking – The chances of a person developing AMD is increased by two to five folds if s/he smokes. The reason being the high rate of oxygen consumption by the retina is severely affected when the oxygen delivery to the retina is prohibited. Smoking also causes oxidative damage that contributes to the development and progression of this disease.
- Family History – A person is more likely to develop AMD if someone in his or her immediate family has had it.
- Gender – Females live longer than the males and so are more likely to develop AMD.
- Race – Caucasians tend to develop AMD more than other races because of their genetic background or pigmentation.
- Prolonged Sun Exposure – Some studies suggest an association between AMD and cumulative eye damage from ultraviolet (UV) rays and other light. This light may damage the retina and increase the risk of AMD.
- Diet – People whose diets are high in fat, cholesterol and sugar and low in antioxidants and green leafy vegetables may be more likely to develop AMD.
- Obesity – People with a BMI (body mass index) greater than 30 are 2.5 times more likely to develop the disease than with that of a lower BMI.
- High Blood Pressure – Just like smoking, high blood pressure also leads to constriction (narrowing) of the blood vessels that nourish the retina, thereby restricting the oxygen flow.
- Eye Color – People with light-colored eyes are more likely to develop the dry type of AMD because the light-pigmented eyes offer less protection from damaging UV light.
- Inactivity – In dry AMD, the retina does not receive adequate oxygen, leading to the death of cells in the macula. Exercise improves cardiovascular health and might help prevent AMD.
- Presence of AMD in One Eye – If a person has AMD in one eye, he or she is more likely to develop it in the other eye.
- Heredity and Age-Related Macular Degeneration – Age-related macular degeneration typically affects people over 50. Scientific evidence shows that genes may play a role in the development of nearly three out of four cases of this devastating eye disease.
Treatment options for the AMD patients
Once AMD has reached the advanced stages, there is no treatment available that can restore the loss of vision. However, early treatment can help and can even prevent AMD from progressing. Researchers have found that people at a high risk of developing advanced stages of AMD can lower their risks by about 25 percent when treated with a high-dose of combination of vitamin C, vitamin E, beta carotene and zinc. These nutrients cannot restore the lost vision but can help in lowering the risk of developing advanced macular degeneration to a large extent. They can effectively reduce the risk of vision loss by as much as 19 percent. But the same nutrients provide no benefit to the patients who have no AMD or early AMD. Some of the treatments and interventions that can delay and possibly prevent intermediate AMD from progressing to the advanced stages are available. These treatments only reduce but do not eliminate the risk of severe vision loss:
- Lucentis or the Anti-VEGF medication injections – These medications were approved by the FDA in June 2006 and they work by inhibiting proteins called vascular endothelial growth factor (VEGF) that stimulate the development of new vessels and also blocking the leakage from the abnormal vessels leading to wet AMD. Overall, about one-third of patients undergoing Lucentis treatment in FDA clinical trials experienced vision improvement.
- Laser Therapy – A combination of a light-activated drug called a photosensitizer and a low-power, cool laser can be used to target the center of the macula. The photosensitizer drug is injected into the bloodstream and is absorbed by the abnormal blood vessels in the eye. This is followed by a cold laser, which activates the drug, closing off and damages unwanted blood vessels. Laser photocoagulation is another macular degeneration treatment for wet AMD. The procedure uses high-energy laser light to destroy or seal off the actively growing abnormal new blood vessels to prevent leakage and bleeding. But the therapy has its own flaws, i.e. it produces many small retinal scars that can cause blind spots in the patient’s visual field. For this very reason, the laser procedures are not widely used to treat the wet form of AMD.
- Implantable telescope – In July 2010, the FDA approved a tiny, implantable device that magnifies images onto the retina to improve central vision damaged by AMD or Stargardt’s macular dystrophy. The implantable Miniature Telescope magnifies the overall image while reducing the relative size of the blind spot that is caused by macular degeneration.
While not all factors that contribute to eye diseases in the elderly are controllable, they can be prevented to a large extent by eating healthy foods, not smoking, protecting the eyes from UV exposure, controlling body weight, blood pressure and cholesterol et al, being active as much as and as long as possible, by wearing safe eyewear and by being aware of any abrupt changes in ones sight and vision.