The only way for people to determine whether or not they have glaucoma is to be examined by an ophthalmologist, a medical doctor who specializes in eye care. The doctor will perform a number of tests. If there are indications that glaucoma is present, other tests can confirm it.
Checking For "Cupping"
Doctors use eye drops to dilate (enlarge) the pupil so they can look through it to the back of the eye. What they are looking for is abnormal "cupping" at the end of the optic nerve that is visible along the back wall of the eyeball. There is usually a slight depression there. If this depression is abnormally large, it is referred to as cupping. Cupping is often the first indication of glaucoma.
Visual Field Test
The doctor will also perform a visual field test to check your peripheral vision (what you can see on your sides while you are looking straight ahead), since that is the vision that glaucoma destroys first.
Measuring Eye Pressure
The doctor uses a simple and painless technique to measure the pressure within the eye. An anesthetic eye drop is given first, to ease any possible discomfort.
If the first three tests indicated that glaucoma might be developing, there are two more tests that can be performed.
Gonioscopy. In this test, doctors place a lens on the surface of the eye to study the drainage channels that should be taking aqueous humor out of the eye. This can help determine whether glaucoma exists and, if so, what type it is.
Photographing the optic nerve. While the eyes are dilated, photographs are taken of the optic nerve. These are studied and kept so the doctor can determine if the condition is changing.