 A person who has it usually has no symptoms until it has progressed to involve the macula, the part of the fundus (eye) where central vision is processed.There is a possible link with HLA-B7 and the condition is more common in Caucasians and individuals in their 40s and 50s.The name of the condition stems from the appearance of snakelike chorioretinal atrophy in the eye and is not contagious.