Glaucoma affects about 5% of those over the age of 65 (approximate estimate) and 10% of those over the age of 80. In other words, about 1 in 20 people over the age of 65 are affected with this condition, so it is a fairly common condition. Glaucoma is commoner in some communities, for example in those from West Africa, and those from the Caribbean. Glaucoma is commoner in some families, and many patients with glaucoma have family members with the condition. Many genes have been identified as causing glaucoma, however generally the condition is not passed on directly and often might skip a generation. Nevertheless, for example, if you have a brother or sister with the condition then the risk of developing glaucoma yourself is increased significantly.