Orthoptists diagnose and treat problems of the eye, especially those related to eye movement and how the eyes work together to focus, known as binocularity. Patients of any age may come to see an orthoptist, but most of their patients are children due to the developmental nature of many binocular disorders. Orthoptists perform diagnostic tests and measurements of color vision, visual acuity, and the pace of motor development related to vision development. After interpreting test results, orthoptists may refer patients to ophthalmic surgeons and other physicians or they may perform nonsurgical interventions such as corrective lenses, patches, drops, exercises, and more. The majority of orthoptists work full time. They practice in hospitals, clinics, private offices, and medical facilities attached to universities as well as visiting schools to administer testing. Some orthoptists teach or conduct clinical research. Orthoptists must complete a 2-year training fellowship after earning a bachelor’s degree, usually with a science or health care major. Typically, orthoptist students evaluate at least 1500 patients as part of their clinical studies. After completing training, they must pass a certifying examination given by the American Association of Certified Orthoptists.