Your eye doctor has a variety of diagnostic tools which aid in determining whether or not you have glaucoma -- even before you have any symptoms. Let us explore these tools and what they do.

The Tonometer

The Tonometer measures the pressure in the eye. If your doctor were to use applanation tonometry, your eye would be anesthetized with drops. Then, you would sit at the slit lamp, and a plastic prism would lightly push against your eye in order to measure your IOP. In air tonometry a puff of air is sent onto the cornea to take the measurement. Since this instrument does not come in direct contact with your eye, no anesthetic eye drops are required.

Visual Field Test

Testing your visual field lets your doctor know if and how your field of vision has been affected by glaucoma. The visual field is an important measure of the extent of damage to your optic nerve from increased IOP. There are several methods of examination available to your doctor.

In computerized visual field testing you will be asked to place your chin on a stand which appears before a computerized screen. Whenever you see a flash of light appear, you will be asked to press a button. At the end of this test, your doctor will receive a printout of your field of vision. Another test which is similar is the Goldmann perimeter. However, in this test, no computer is used. The examiner records your answers whenever you indicate that the light is in view.


Using an instrument called an ophthalmoscope, your eye doctor can look directly through the pupil at the optic nerve. Its color and appearance can indicate whether or not damage from glaucoma is present and how extensive it is.