ENG
electronystagmography
VNG
Videonystagmography
What is EOG measuring?
measures the changes in voltage due to eye movement
What is VOG measuring?
use of infrared light sensors to detect eye movement
Horizontal channel
Right eye movement is shown as an upward pen tracing
Left eye movement is shown as a downward pen tracing
Vertical channel
Upward eye movement is shown as an upward movement of the pen
Downward eye movement is shown as a downward movement of the pen
Benefits to ENG
Initially less expensive
Can record a larger number degrees of eye movement
can be used for certain populations (individuals with droopy eyelids, those who can’t keep eyes open, children younger than 5)
Drawbacks to ENG
affected by ambient light (needing frequency recalibration)
affected by retinal pathology
eye blink artifact
less accurate measuring vertical eye movement,
not sensitive to torsional eye movement,
Bell’s Phenomenon, and DC drift.
Benefits to VNG
Does not require electrodes
can video record movements for later analysis
easier to monitor eye movements while testing
easier to measure individual eye movements (if bilateral recordings)
Drawbacks to VNG
Narrow angular range
can’t be measured with eyes closed
size and weight of goggles
can be affected by eye makeup.
What is the potential we are measuring for ENG?
Uses EOG to record eye movements during a series of tests designed to assess the function of the vestibular and oculomtor systems. EOG is recording of changes in DC voltage that is caused by the eye movements