Spending more than five hours a day in the summer sun can double the risk of developing a type of blindness that commonly afflicts the elderly, researchers said on Wednesday.

A preliminary study of 5,000 middle-aged and older adults confirmed an association between exposure to bright summer sun when younger and age-related maculopathy (ARM). The problem, which is largely untreatable, occurs when damage to the retina causes hemorrhaging and other injuries that gradually degrade sight, beginning in the center of vision.

"These results fit with a small body of epidemiologic evidence that indicates that exposure to bright sunlight may be a risk factor for early ARM," researcher Karen Cruickshanks of the University of Wisconsin, Madison, wrote in this month's issue of the journal Archives of Ophthalmology.

In five-year follow-up examinations completed in 1995, the study found subjects who reported spending five or more hours a day outside during summer when in their teens and in their 30s were at double the risk of developing the vision problem, compared to those who reported spending little time outside during those younger years.

There was only a slight protective effect if hats or sunglasses were used during the heavy exposure periods.

Cruickshanks emphasized that her results were preliminary and that longer-term studies were needed but added the study may "support the idea that ARM may be partly preventable through modification of lifestyle factors."

(From ChinaDaily)