SYDNEY: Descendants of the famous Bounty mutineers who now live on an isolated Pacific Island have among the lowest rate of myopia in the world and may hold the key to unlocking the genetic code for the disease, according to a new study.

A study of residents on Australia's Norfolk Island, 1,600 km (1,000 miles) northeast of Sydney, showed the rate of myopia, or short-sightedness, among Bounty descendants was about half that of the general Australian population.

Fletcher Christian led a mutiny on the British Royal Navy ship HMS Bounty against captain William Bligh in 1789 in the South Pacific. The mutineers settled in Tahiti but later fled, along with their Tahitian women, to remote Pitcairn Island to escape arrest.

Some 60 years after arriving on Pitcairn, almost 200 descendents of the original mutineers relocated to Norfolk Island to avoid famine.

"We found the rate of Pitcairn group myopia is approximately one-half that of the Australian population and as a result would be ranked among one of the lowest rates in the world," said David Mackey, the managing director of Australia's Lions Eye Institute which led the studies.

Mackey said there may be genetic differences in the Norfolk Island population that could lead to breakthroughs in the causes of short-sightedness, but added it was also apparent that spending too little time outdoors raised the risk of myopia.

"The big cities of East Asia like Singapore, Taiwan, Hong Kong, and mountain cities of China, myopia has become very common and we think that there are environmental factors that have changed," he said.

Myopia affects one in six people in Australia and more than one in four in the United States. A quarter of the world's population, 1.6 billion people, suffer from the disease.