Eye pressure is measured with a tonometer that is placed on the eye for a few seconds. Because eye drops are first applied to numb the eye, you do not feel the tonometer touching it. You do see a bright blue light approaching. The tonometer gently pushes a little bit against your eye. To what extent the tonometer can indent the eye depends on the eye pressure and that is how it is being measured.
Another type of tonometer applies pressure to the eye with a puff of air. The advantage of this method is that it is not necessary to numb the eye or to touch it, the disadvantage however being that measurements are somewhat less accurate.

Your eye doctor can look inside your eye through the pupil. This is done to view the optic nerve. Sometimes a picture will be taken. Progressive cupping of the optic nerve, documented during consecutive exams, is a sign of (worsening of) glaucoma. Sometimes an eye drop has to be applied to open the pupil and allow full view of the optic nerve. In that case, vision is slightly blurred for about 2 hours, disabling you to drive a car.

The perimeter is used to check the damage to any area of vision. This test can detect visual field loss long before you are able to observe this yourself. The perimeter is a hemisphere against which small lights are being projected, one by one. You are asked to place your chin on a stand, sit still and look straight ahead to the center of the hemisphere. You have to press a button every time you see a light appear. It can take up to about 10 minutes to test one eye. Obviously your cooperation and attention is very needed. After the test, the computer processes the data and a map of your visual fields can be printed out.

Depending on the gravity of the situation, these test are repeated one to four times a year so that treatment can be initiated or changed timely.