Visual Motion Sensitivity
Another common symptom experienced by concussed individuals is visual motion sensitivity (VMS). For these concussed patients, driving on busy roads or walking down supermarket aisles can visually overwhelming. These dynamic and moving environments, which Gibson has termed “optic flow,” can be difficult for the concussed patient to manage as it can induce visual vertigo.
According to one theory, VMS is due to a sensory conflict between the visual, vestibular and somatosensory systems caused by the concussion. Another theory suggests that as result of a vestibular disturbance from the concussion, there is a sudden dependence for one’s balance on the visual system rather than on vestibulo-proprioceptive inputs.
In any case, a repetitive moving stimuli in the visual field of a concussed individual may result in the sudden onset of visual vertigo. To simulate optic flow, Dr Ken Ciuffreda and colleagues have advocated the use of an Opto-Kinetic (OKN) drum held in a patient’s peripheral field to create a relatively controlled visual motion.1,2 We have used the OKN feature of the Smart Optometry App installed on an I-PAD as another way to generate this motion.
Holding the I-PAD generated OKN pattern about 6-8 inches away and angled to either side of the face of a patient who is gazing forward, the VMS patient will have difficulty disambiguating the external peripheral motion from their internal self-generated motion, resulting in a strong provocative response. Like the Senaptec Strobes, rehabilitation training strategies using peripheral motion stimulation can help a concussed patient to habituate or become desensitized over time.
- Ciuffreda KJ. Visual vertigo syndrome: clinical demonstration and diagnostic protocol. Clinical Eye Vis Care. 1999; 11:41-44.
- Ciuffreda K, Tannen B, Ludlam DP, Han MH. Vision-based concussion/mild traumatic brain injury diagnostic tests/ biomarkers: An update and reappraisal. Vision Dev & Rehab 2019;5(3):187-193.