For the most common type of glaucoma (open-angle glaucoma), symptoms gradually increase so subtly that it’s hard to notice. Once symptoms do appear, often the disease is fairly advanced. It’s important to get your eyes checked once a year, especially if you are over the age of 60, have a family history of glaucoma, or if you have certain medical conditions such as diabetes, heart disease, high blood pressure, or sickle cell anemia.