It affects the macula, the center area of the retina, and can lead to declines in sharpened central eyesight and blindness even, experts say. Scientists have linked a number of factors to the problem including genetics already, smoking and nourishment, said Bernstein, who was not involved in the new study. However, treatment for AMD may be limited based on the type of macular degeneration a person develops, he said. Prior research has produced combined findings about links between carotenoids and macular degeneration, the researchers said.Subjects between the ages of six months and 99 years who hadn’t previously received carbamazepine and who as a rule have received it at the time of screening were invited to participate in the study. We excluded subjects who had a past history of carbamazepine allergy, those who had undergone bone marrow transplantation, and the ones who were not really of Han Chinese descent. Status regarding Han Chinese descent was determined by using a multiple-choice questionnaire that asked the topics to recognize the ethnic group of their parents and grandparents. We prescribed and provided carbamazepine to all subjects at the time of the screening visit, but we requested that they defer taking the medication until we had obtained and relayed to them their genetic test outcomes.