FAQ's

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Q. How is glaucoma diagnosed?
When your eye doctor examines your eye, he or she can detect glaucoma damage by the appearance of your optic nerve. A normal healthy nerve has a small cup-shaped hole in the center (• See Photo). As damage from glaucoma progresses, this hole in the center of the nerve enlarges, and replaces the healthy tissue of the nerve (• See Photo). Your eye doctor can detect progression of the disease by periodically examining the appearance of the nerve.

Your doctor may also take photographs of the nerve in order to document the appearance at a specific point in time. This allows better comparison in the future to be certain that the disease has been stabilized. These photographs, called disc photos, are particularly helpful if your doctor has decided that you are a “glaucoma suspect.” A glaucoma suspect is a person whose optic nerve appearance is suspicious for glaucoma, but does not demonstrate definite glaucoma damage. If you are a glaucoma suspect, your doctor will want to examine your optic nerve two or three times a year, and compare to the baseline disc photos to detect definite glaucoma damage as soon as it occurs. This will allow your doctor to begin treatment before the glaucoma has a significant effect on your vision. A relatively new method of evaluating early glaucoma damage to the optic nerve is Heidelberg Retinal Topography (HRT). HRT uses a laser to scan the surface of the nerve then a computer determines if there has been any change from previous examinations (• See Photo).

Another way to measure the amount of damage to the nerve is to measure the amount of peripheral or side vision that has been lost. Glaucoma does not affect your central reading vision until the late stages of the disease. At this late stage, a glaucoma victim may already be partially blind. Therefore, it is important to measure the peripheral vision in the early stages of the disease, so that proper treatment can be given to prevent blindness. This is accomplished with visual field testing (• See Photos), which is an examination that measures the amount of vision lost.

To test the visual field, your doctor uses an instrument that flashes lights of various intensities. You place your head against a head rest and stare at a target light directly in front of the eye being tested. The machine then flashes lights in your peripheral (side) vision. Some of these lights are bright and easy to see. Others are so dim that they are impossible to see even if you have no visual damage. Most lights are somewhere in between. When you see the light, you press a button and the machine registers your response. The machine then prints out a map showing any areas that you cannot see properly. Your eye doctor can repeat this measurement periodically to determine if the glaucoma treatment has been effective in stabilizing the damage.

There are other types of specialized testing that have recently become available, such as measurement of the thickness of the nerve with a technique called scanning laser polarimetry (GDx Nerve Fiber Analyzer) or optical coherence tomography (OCT) (• See Photo), and short wavelength perimetry, which uses colored lights to test the visual field (peripheral vision). Both of these technologies are particularly helpful if a person is suspected of having glaucoma, but there is no definite damage visible (glaucoma suspect).

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