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Home » Eye Care Services in St. Louis » Advanced Technology » GDx Optic Nerve Fiber Analyzer

GDx Optic Nerve Fiber Analyzer


The GDx optic nerve fiber analyzer takes a very detailed image of the optic nerve and its approximately 1 to 1.5 million fibers that go from the back of the eye to our brain to be processed for good vision.  This technology is used primarily to assess the risk or advancement of glaucoma, which is a disease that slowly destroys the optic nerve.  It is an objective test and requires no responses from the patient, and it usually takes no more than 5 minutes to complete.  It does not require the patient to be dilated, although in some cases it can help.  

It has been known since the mid-19th century that changes in the optic nerve appearance correlate with vision and visual field loss in glaucoma. Increased attention to the structure and appearance of the optic nerve has been a key element in understanding glaucoma.

Recently, techniques utilizing sophisticated laser scanning with digital image processing have been used to assist clinical evaluation of the optic nerve and the nerve fiber layer. The optic nerve (optic disc, optic disk, optic nerve head) area changes in early life but is usually stable after age 10. 

The optic nerve appearance often provides evidence of the presence and progression of glaucoma. Changes in the optic nerve which are tracked to provide evidence of glaucoma are classically considered to be cupping and pallor of the disc. Increased intraocular pressure is the greatest risk factor for development of ganglion cell loss. As the rim thins from ganglion cell loss, the cup becomes larger and often deeper exposing the lamina with increased pallor of the cup.

The most important aspect of the GDx is that it can pick up changes in the optic nerve BEFORE vision loss occurs.  In the past, eye doctors had to wait for glaucoma to cause vision loss before initiating treatment.  This allows for much more proactive care in managing glaucoma.