Age-related macular degeneration (AMD) is the leading cause of blindness. It is just one form of macular disease, which affects the eye’s retina. An estimated 500,000 people in the UK suffer from AMD, 40% of these are over the age of 75. Also it is the leading cause of blindness in developed countries like USA, Canada and Australia. It was thought that the incidence of this disease is very low in a developing country like India, a decade earlier. But this scenario is no more true now, as we are seeing more and more cases of AMD.
What is AMD?
AMD is the most common form of macular disease, which affects the central part of the retina. It is an age-related process and usually develops after a person reaches 50 years. It generally involves both eyes, although they may not be affected at the same time or to the same degree. Some 90% of these cases are dry AMD which cannot be treated but 10% are wet ADM. Dry AMD means visual cells simply stop to function. Wet AMD is by far the most aggressive form of the disease. The condition is caused by the growth of new blood vessels under the centre of the retina. These can leak fluid, causing scar tissue to form and destroying central vision in a period of between two months and three years. Peripheral vision is retained. The condition causes problems reading, seeing small objects and distorted vision.
What are the symptoms?
In the early stages of AMD, central vision may be blurred or distorted. Objects may take an unusual size or shape. This process can happen quickly or develop over several months. People with the condition may become very sensitive to light or actually see lights that are not there. There may be some discomfort, although overall the condition is not painful.
How is AMD treated?
Variety of medical treatment is tried over several years, like prescribing high doses of B-complex tablets, Anti-oxidants etc. But the results are not good. But in recent years, PDT is tried in developed countries and has given fairly good results.
Photo dynamic therapy (PDT) is the first effective treatment for correcting wet AMD. It is a relatively new treatment and was first used in the UK in 1999 by doctors at the Royal Liverpool University hospital. PDT is thought to be suitable for around a third of patients with wet AMD since it is effective only if the condition is caught early. It involves injecting a light sensitive dye called Visudyne into the body, which sticks to the lining of abnormal blood vessels within the retina. The process takes half an hour. A light is then shone into the area through a contact lens, activating the dye and causing it to damage the abnormal blood vessels.
The treatment may need to be repeated every three months and it is fairly costly.
Side effects include lower back pain, a reaction to light and a temporary loss of vision in around 3% of cases.
– Dr.H.S.Mohan
