Glaucomatous optic neuropathy is characterized by changes in the appearance of the
optic disk, pattern of visual field loss, and death of retinal ganglion cells. There is evidence to indicate that large ganglion
cells, presumably those in the magnocellular pathway, are affected selectively.
The neucodia device utilizes a novel version of the isolated-check
VEP (icVEP) technique (US patent) designed to tap cortical activity initiated primarily by afferents in the magnocellular
pathway. The techniques applied in this test incorporate quick and objective measurement procedures.
Procedure: Three electrodes were placed at Oz
(occipital) referenced to Cz (vertex) with floating ground at Pz (parietal). VEP was sampled in synchronize
with the stimulus frame rate. Statistic algorithm was applied for 8 independent runs to determine a circular 95% confidence
region around the mean, and a signal-to-noise ratio (SNR) defined
as the ratio of the mean and the radius of the circle was derived
as an indication for glaucoma likelihood. Total test time after applying electrodes is about three minutes for both eyes.
RIFGT: Stimuli: Arrays of low-contrast isolated-checks presented
in appearance-disappearance mode.