Glaucoma is a disease that damages the nerve fibers carrying images from the eye to the brain. The nerve is the optic nerve it is like a cable made up of many fibers (like wires). Once damage occurs blind spots appear in your visual field. As you can imagine it takes time for enough fibers to be damages for recognition of a ‘blind spot’.
Blindness may eventually result. In the USA it is the leading cause. As I hinted once glaucoma causes damages it can not be reversed. However medicated eye drops and laser surgery can reduce pressure and help prevent further damage. In certain people oral medications are also prescribed to ward off blindness. A simple eye pressure measurement is not enough to recognize glaucoma-you need a complete eye exam. There are many types of glaucoma. Please read more about this condition, treatments and research at this website.