CHICAGO (Reuters) - Taking vitamin D and eating fish -- especially those high in omega-3 fatty acids -- may reduce the risk of the most common cause of blindness among the elderly, researchers said on Monday.Doctors do not know how to prevent age-related macular degeneration, the leading cause of blindness after age 60, but two studies in the Archives of Ophthalmology suggest nutrient-based treatments may help.>>> Discuss This Story