Age – Related Macular Degeneration ( AMD ) is a condition in which the Macula of the eye’s retina degenerate in old aged persons. This condition is one of the leading causes of blindness after the age of 50. Other leading causes of blindness among the elderly, are cataract and diabetic retinopathy. While cataract and diabetic retinopathy are well known, most people are not aware of AMD.
This progressive condition affects the macula, a small spot on the retina responsible for central vision. When macula degenerates, the patient sees a grey or dark spot in the centre on their visual field. When the patient looks at someone, the face where the person fixates vision appears blurred, especially in dim light.
Indians are prone to get it in their 40s. It rarely causes total blindness – most people retain good peripheral vision – but the loss of central vision is very damaging as it affects the person’s ability to drive, read, do fine near work and appreciate colours. AMD makes it difficult to even recognize family members and friends.
Exact cause of AMD is not known, but age, genetics and smoking are believed to be the primary factors. It is more common in females. Exposure to sunlight is also a factor. People who have moderate to severe high blood pressure and high cholesterol are at higher risk of developing AMD after the age of 40 – 50 years of life.
AMD IS OF 2 TYPES : DRY AMD AND WET AMD
DRY AMD :
This affects about 90 percent of the patients afflicted by AMD. Deposits called drusens collect in the macula and this results in marked visual loss in the central axis of the person’s field of vision. Dry AMD progresses slowly, usually starting in one eye and nearly always spreading to the other eye. Symptoms include blurred vision, and difficulty in recognizing faces at a distance. Patient needs more light to function.
The disease comes to light when both eyes get involved and the patient seeks an eye examination due to blurring of vision. Investigations have confirmed that a combination of vitamins C, E and beta – carotene along with zinc and copper significantly reduces the progression of dry AMD. To prevent further vision loss, it is now recommended that vitamin therapy begin immediately upon diagnosis. Anti-Oxidants play an important role in delaying the progress of the disease. Leafy green or coloured vegetables, such as spinach, lettuce, broccoli and carrots may reduce the risk of AMD. Also eating fish may prevent the development of AMD. Although many ophthalmologists believe that patients with poor vision cannot be helped much, a large number of patients with dry AMD can see better by adjusting lighting or using handheld magnifiers and other low visual aids.
WET AMD :
Only 10 to 15 percent of people develop this type of AMD, but it causes a far more rapid and severe vision loss than dry AMD. Abnormal blood vessels leak fluid into the macula, causing thickening of the macula and cause blurring of vision. An early symptom is that straight lines appear wavy. Early treatment is of utmost importance to save as much vision as possible. A person with wet AMD can lose a lot of vision in just a few days or weeks.
When a person sees wavy lines he should see a retina specialist and receive treatment that saves eyesight. Photodynamic therapy (PDT) was the treatment of choice earlier. Visudyne, was the drug used in PDT. Before its release in 2001, the only treatment for wet AMD was to seal the leaking blood vessels with a hot Laser. Unfortunately, the laser scarred any tissue it touched, resulting in permanent vision loss in that area.
In PDT, Visudyne ( vertiporfin ) is injected into the arm, and then activated by an infrared laser light that seals the blood vessels in the eye to prevent further leaking. The process does not harm healthy tissue and it is not painful. Best of all, those who receive PDT early enough do not lose any more vision and occassionly regain some. But, PDT is now almost given up. The mode of treatment nowadays is Intra – Vitreal Injection of ANTI VEGEF i.e. vascular endothelial growth affecting factors like Avestin, Lucentis or Macugen. The results with these have been quite encouraging.
Another laser procedure, called transpupillary thermotherapy ( TTT ), has been available in India since 2000. It costs around Rs. 1000/- to Rs. 3000/- per treatment. It is as good as PDT, but this has not been confirmed by large scale clinical trials.
Most AMD patients adapt well because they never become totally blind, and with vitamin therapy, TTT and PDT, fewer people will lose significant central vision. In future, new treatments such as silicon chip implants, gene therapy, retina surgery and transplants may restore vision to those who have lost it due to AMD or other eye diseases.
Preventive measures include not smoking, wearing a hat or sunglasses when in the sun, and monitoring blood pressure and cholesterol levels.
A healthy diet and regular exercises are also helpful. Some people might consider taking a multivitamin. Everyone should have an annual eye examination beginning at age 50, or earlier if there is a family history of AMD. And, a couple of times a week, cover your eyes one at a time and look at the lines on a graph or a calendar. If they look wavy or blurred see a doctor immediately. For an early detection of AMD eye doctors supply an Amsler’s Grid chart to the patient. This chart has a graph with horizontal and vertical lines with a central fixation spot. Patient is advised to see this chart daily with one eye at a time. If these lines appear wavy or distorted he must consult a specialist immediately for clinical evaluation and treatment.
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