Age related macular degeneration (AMD), an irreversible condition, has suddenly risen to become the third biggest eye disease in India, next only to cataract and diabetic retinopathy and corneal scars.

AMD is recognised as the biggest cause of irreversible vision and retinal blindness in the US and Europe.

The sudden rise of AMD in India was revealed in a study conducted in Andhra Pradesh by L.V. Prasad Eye Institute. Earlier the estimated prevalence of retinal diseases was 10.3 per cent of which AMD constituted 2.7 per cent. That has now doubled, the study showed.

AMD generally strikes at about age 50. A person whose vision blurs in the centre may have AMD. It is a complex disorder and unlike other eye diseases treatment is limited and expensive and there is no reliable cure.

Change in food habits, smoking, hypertension, increase in cholesterol are cited as reasons for the increase in AMD incidence.

The eye institute also found a genetic basis for AMD. The Brien Holden Eye Research Centre of the institute stated in a report published in Investigative Ophthalmology and Visual Sciences that variation of a gene Complement Factor-H increased the risk of AMD by five to ten times.

Dr R. Narayanan, a retinal diseases consultant of the institute, said that the disease affects the macula, a part of the retina. Macula is the part on which light rays are focused.

Intake of anti-oxidants like Vitamin E, Vitamin C and Zinc can slow the onset of AMD if not prevent it. "There is no awareness of the disease in the public," the doctor said. "We see at least two to three patients a day at our institute alone. When we compare the figure with those three years ago, it is almost double."

Treatment can be lengthy and expensive. In photo dynamic therapy, a cold laser shrinks abnormal blood vessels and decreases swelling. It costs around Rs 60,000 per sitting and is spread over three sittings.

Macugen, a medicinal drug, is injected into the eye. Each injection costs Rs 40,000 and Between 10 to 20 per cent of patients show improvement.

Between 20 to 30 per cent of patients show improvement with Avastin, a drug used for intestinal cancer treatment. It costs Rs 1,000 injection.

Lucentis was launched in the US in July this year but it costs $2,000 a shot. Repeats indicate that 30 to 40 per cent of patients are benefited.