Standard testing, electrophysiology can work together for early glaucoma detection
PERG and VEP aid in earlier detection
Structural tests such as Humphrey visual field (HVF) and OCT provide valuable information, but electrophysiological tests of the retina and neurovisual pathways are objective tests that detect functional abnormalities. Studies have determined that pattern electroretinography (PERG) can detect abnormalities in patients up to 8 years earlier than structural testing. Additionally, because electrophysiological tests are objective, as opposed to subjective functional testing such as visual fields, the results are particularly reliable.
Visual evoked potentials (VEP) can help determine field loss by measuring the amplitude and latency of electrical activity from the retina to the visual cortex. Amplitude indicates the strength of the signal. Latency measures the length of time it takes for the signal to travel to the visual cortex from the retina. Increased latencies can indicate issues that affect the myelin sheath, such as optic neuritis or multiple sclerosis.
PERG measures function specific to the retinal ganglion cells. This test is useful in detecting diseases that have an expected pattern of macular degeneration. Electrically active cells in the retina elicit a stronger or weaker signal depending on the cell types that are stimulated.
Using PERG in conjunction with VEP and other tests is useful in distinguishing between retinal and optic nerve disorders as well as improving detection of neuropathies and maculopathies……..
Read more: http://www.healio.com/ophthalmology/glaucoma/news/print/ocular-surgery-news/%7Bf7ca44b7-d6be-47fa-9008-34abbb0fc945%7D/standard-testing-electrophysiology-can-work-together-for-early-glaucoma-detection