Vision Testing
According to the Mayo Clinic, your optometrist may use a specific vision test called a perimetry that will check the range of you peripheral vision. During a perimetry test, you will look into a bowl-shaped surface at a central point. Lights will flash within your field of vision, and the doctor can effectively map loss of peripheral vision by noting which points of light you can and cannot see.
Examination
Your doctor will examine the back of your eye by using a special instrument called an ophthalmoscope. He will look for changes in the optic nerve fibers, which is a key sign of the beginning stages of glaucoma. He may take a photograph of your optic nerve to help him compare the loss of pressure.
Pressure Measurements
According to The Eye Surgery Education Council, there are several tests used to measure eye pressure and pressure loss. Some of these require that the instrument used be placed on the surface of your eye, so your eyes will be numbed with eye drops before the test. These tests include tonometry, using either a blue light or a puff of air to take a measurement of your intraocular pressure and pachymetry, which measures the thickness of the cornea to see how it relates to the ocular pressure.
Other Tests
If glaucoma is diagnosed, your doctor will perform other tests used to measure the extent of the glaucoma. These may include the gonioscopy, in which a special contact lens is place on the numbed eye to examine the angle where fluid drains from the eye and a new method of retinal and optic nerve imaging, in which a low intensity laser light is used to measure the thickness and shape of the optic nerve. This procedure is similar to a CT scan or MRI but with no radiation involved.
