Candidates will undergo a medical history and comprehensive eye examination. The eye examination includes dilation of the pupils to fully examine the retina. In some studies, photographs of the eye are required. This is done using fluorescein angiography. In this procedure, a dye called sodium fluorescein is injected into the blood stream through a vein. After the dye reaches the blood vessels of the eye, photographs are taken of the retina. Other diagnostic procedures may include physical examination, questionnaires, routine laboratory tests and other standard or specialized tests, as needed.