Vestibular Eye Movement Testing
Why Measure Eye Movements to Test the Vestibular System of the Inner Ear?
Clear vision requires a stable image on the retina. However during normal everyday activities there are considerable head movements and so to provide a stable retinal image during head movements there has to be a mechanism to stabilize the eye. Receptors in the vestibular (balance) system of the inner ear detect head movement because head movements cause fluid flow in the semicircular canals of the inner ear resulting in receptors being activated. Neurons from those receptors drive the eyes via short fast pathways and act to correct for the head movement. In healthy people the eye movement is equal and opposite to the head movement so the image on the retina of the eye is stable and visual perception is clear. This process is called the vestibulo-ocular reflex (VOR). So while jogging it is possible to read signs because the vestibular receptors correct for head movements and provide stable gaze, or in other...
- MacDougall HG, McGarvie LA, Halmagyi GM, Curthoys IS, Weber KP (2013a) Application of the video head impulse test to detect vertical semicircular canal dysfunction. Otol Neurotol 34(6):974–979. doi:10.1097/MAO.0b013e31828d676d [doi]Google Scholar
- MacDougall HG, McGarvie LA, Halmagyi GM, Curthoys IS, Weber KP (2013b) The video head impulse test (vHIT) detects vertical semicircular canal dysfunction. PLoS One 8(4):e61488. doi:10.1371/journal.pone.0061488 [doi]Google Scholar