Vestibular Rehabilitation Therapy

Visual Dependence training

This page is primarily intended to be a reference for patients who have been referred for therapy. 

Timothy C. Hain, MD Page last modified: July 14, 2009

Visual Dependence Exercises

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.

Visual dependence training with a stationary anchor.

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.

Protocol

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.

1. Visual stimuli
   1. Eyes closed (this is for practice of mental imagery)
   2. Blank background
   3. Busy background (i.e. checkerboard)
   4. Very busy background (i.e. grocery store). This is often a tough one.
   5. Very busy moving background
      1. crowds
      2. windy outdoors,
      3. watching waves come in
   6. Misleading background -- this is the main exercise. One does not have to do all of these. See the commentary above concerning use of a visual anchor.
      1. walking with a crowd
      2. walking against a crowd moving the other direction,
      3. rotating visual surround such as a disco-ball
      4. twisting golf umbrella
      5. x2 exercises - -where head and target move in different directions
      6. x0 exercises -- head and target move together
2. Environmental contexts with strong visual inputs
   1. Driving, in broad daylight, evening, dark, sleet/rain
   2. Going to the grocery store
   3. Going to the movies
   4. Escalaters
3. One combines the other sensory stimuli outlined in the other protocols to make this more difficult. For example, walking on sand at the beach, with head rotating back and forth, with the waves coming in.

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.