The GDxVCC - Technology

The Retinal Nerve Fiber Layer (RNFL)

The GDxVCC measures the phase shift of polarized light passing through the eye. This phase shift is affected by the arrangement of the RNFL tissue thickness. If the RNFL is thinning, a recorded measurement is taken and imaged (see below). The RNFL carries the signal to the brain giving us our peripheral field and vision. Glaucoma destroys the RNFL and, thus, causes blindness.

The new GDX Variable Corneal Compensation (VCC) corrects for each patient's individual abberation caused from optical structures within the eye to examine the RNFL. The GDx VCC can detect minute changes many years in advance before your vision or peripheral field is lost.

Examples of what this test may reveal:

Normal

A healthy human retina. Orange colors are the 'hot' areas, i.e. normal, with colors transitioning to 'warm' colors, or the yellow to bluish areas. As we examine your eyes over time, we'll look for any unusual trends--as seen in the next pictures.

Early RNFL changes

Here we see some 'cooling' off of an area of the RNFL--- which correlates with loss of nerve tissue. The RNFL changes signify a loss to your peripheral field is imminent. The right picture shows 'probability spots' with varying colors that tell us how likely you have Glaucoma. The red spots indicate a stronger liklihood of you have damage to your RNFL from Glaucoma or another issue that may mimic a similiar look.

Moderate RNFL changes

Cool colors dominate the GDxVCC map (on the left picture). Visual field changes will be apparent. You may notice some clumsiness, worsening night vision or headaches among other things.

Advanced RNFL changes

At this point, your peripheral field most likely will be just about gone leaving you with just central vision-- which will slowly start to go. Most areas of the 'probablilty spots' are reddened (right picture)-- meaning the RNFL is undergoing profound damage and blindess is very likely.

Bottom line: We will look for trends over time to catch this disease early on, so we can treat it. Risk factors for developing Glaucoma include, among other things, folks with a high degree of prescription, menopausal women, people of African descent, diabetics and those with a family history, especially if a brother or sister has it.