Glaucoma is not contagious. It is not an infectious disease; rather, it is a group of diseases characterized by increased eye pressure, leading to optic nerve atrophy and vision decline. The most common cause is genetic factors, meaning if elders or parents in the family have this condition, the incidence of glaucoma in their offspring will also be higher. It is an eye disease caused by anatomical abnormalities of the eye. Additionally, some cases of glaucoma are caused by trauma or other reasons, so glaucoma is not contagious.