Now a new exam that helps meet the need for early detection and more sensitive follow-up is available the GDx Nerve Fiber Analyzer. The GDx is an advance for many reasons. It is objective—it doesn't rely on your response to various stimuli that may influence the results. And the support and the GDx is able to determine if you have glaucoma prior to you experiencing any vision loss. Existing tests have limitations. For example, the tonometry test that measures ocular pressure is ineffective for detecting glaucoma in many people. Half of diagnosed glaucoma patients are found to have normal intraocular pressure, yet still have the disease. Perimetry (visual field testing) measures vision already lost to test for glaucoma and can be unreliable. The GDx exam is very fast—usually less than 5 minutes—and completely painless. No pupil dilation is necessary: the eye is not even touched. You simply rest your chin on the support and focus on the light indicated. A safe, invisible laser scans the back of your eye and acquires an image in less than one second.
The result of the GDx exam is a color-coded "thickness map" of the nerve fiber layer at the back of your eye. This provides your doctor information that he can't get from other exams and helps him determine whether you have glaucoma.
GDx is used to test for glaucoma and to track the progression of the disease. If your doctor determines you have glaucoma he or she will continue to use the GDx to check for damage or changes in your condition. If you do not currently have glaucoma, but are in a risk group for the disease, your doctor may recommend that you be examined.
Because GDx is a new technology, it may not be covered by your insurance carrier or Medicare in your state. Ask your doctor about payment options. If your insurance doesn't cover the exam, your doctor may ask that you pay for the exam yourself.