Tar that enters the body in cigarette smoke hastens the onset of age-related macular degeneration, according to Duke University Medical Center researchers.

High exposure to ultraviolet light and a high-fat diet appear to increase the effects of smoking on macular degeneration, though smoking alone–and even second-hand smoke–can hasten the disease, researchers said.

The tar contributes to the formation of deposits and thickening in the retina that leads to AMD. The disease is the leading cause of blindness among older adults. The results of the study appear in the February 2006 issue of  the journal Investigative Ophthalmology & Visual Science.