One of our latest additions in electronic wizardry is the GDx Scanning Laser Polarimeter from Zeiss Meditec. This instrument scans the retina to measure the thickness of the nerve fiber layer which transmits visual signals along the optic nerve to the brain.
     Glaucoma is an optic nerve disease in which nerve fibers progressively die, leading to impaired peripheral (side) vision, tunnel vision, and blindness if not treated. Obviously, the sooner the diagnosis, the better chance of preserving vision.
      It used to be we would wait for the visual field to be affected to begin treatment, but newer research shows that we can lose up to half of our  retinal nerve fiber layer before a visual field defect shows up. The trend has become to begin treatment when changes to the optic nerve are apparent. The GDx takes it a step further and measures the change in the actual nerve fibers even before the optic nerve shows change.
     Who should have a GDx scan? Anybody with a family history of glaucoma, suspicious looking optic nerves on examination, or higher than normal intraocular pressure (you know, your favorite air puff test). If you are at risk for glaucoma, the test may be reimbursed by your major medical insurance or Medicare.