Timothy C. Hain, MD Page last modified: July 14, 2009
It is not unusual for vestibular therapists to propose "interesting" treatments. For example, therapists might have patients smear their glasses with Vaseline. The rationale is to reduce "visual dependency", which is an inappropriate reliance on visual input, in situations where it might be better to use somatosensory or vestibular inputs. In certain situations, this seems like a good idea. Does smearing vaseline on glasses reduce visual dependency ? Nobody knows. If we had a reliable method of measuring visual dependence, perhaps we could relate it to interventions. At this writing, posturography seems to be the closest to being a measure of visual dependency, but it is somewhat expensive. Cheap, quantitative and reliable methods are needed to measure visual dependence.
Virtual reality training (see here) might offer a method of reducing visual dependency. This promising technology is in its infancy right now, and research studies are needed to validate it. Right now, the equipment is expensive but it is rapidly getting cheaper.
We recently have proposed (Chang CP, Hain TC. "A theory for treating visual vertigo due to optical flow" CyberPsychology and Behavior. 9-2007), a theory for treating visual dependence. The essence of this idea is that, unlike the usual paradigm used in virtual reality training, it might be better to combine a gradually increasing, central moving field with a surrounding visual surround. The availability of both a "visual anchor" as well as a destabilizing input, might allow the health care provider to gradually recalibrate a person's oversensitivity to optic flow.
Visual dependence training is a mixture of the gaze-stabilization protocol and balance exercise protocol, but with a greater emphasis on suppressing abnormal visual input in real-life situations.
Heavy exposure to optokinetic stimulation does not have a strong effect on either optokinetic nystagmus (OKN) or circularvection (McDermott et al. 1999), but it may be helpful in visual dependency.
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