Visual Dysfunctions Causing Dizziness and Balance Problems
Aneisokonia is a condition where there is an excessive difference in
prescription between the eyes, which causes a significant difference in
magnification of images seen between the eyes. When this magnification
difference becomes excessive, generally more than about 4%, the effect
can cause disorientation, eyestrain, headache, and dizziness and balance
disorders. Treatment is with contact lenses, or special magnification
size matched lenses called isokonic lenses.
Normally the eyes work in perfect synchrony. However, following
trauma, fever, stroke, deconditioning, or sometimes for no apparent
reason, one eye will aim slightly higher than the other will. When mild
and not enough to cause double vision this is called a hyperphoria. If
excessive to the point of causing double vision, it is termed a
hypertropia. In an effort to adjust to the vertical misalignment of the
eyes, the person will frequently tip their head to mechanically help
align the eyes. This in turn can cause disorders in the fluid of the
inner ear and resultant dizziness and balance disorders. Treatment is
with therapy to correct the muscle imbalance and prisms.
Binocular Vision Dysfunction
Binocular vision refers to how the eyes work together as a team. It
is the coordination of convergence and divergence (eye teaming and
alignment) with accommodation (focusing). Following trauma, fever,
stroke, deconditioning, or sometimes for no apparent reason dysfunctions
can occur causing the eyes to be weak or overactive. When this occurs,
the eyes will manifest a tendency to drift outwards or inwards. This
in turn can cause eyestrain, double vision, muscle spasm and excessive
peripheral visual stimulation, which in turn can trigger dizziness and
balance problems. Treatment is with lenses, prisms and therapy.
Double vision is among the most disorienting and devastating vision
disorders. People suffering from double vision will often times go to
great lengths to alleviate the double image because it is so bothersome.
Many will actually even patch, or cover an eye, thereby eliminating
the vision from one eye just to get rid of their double vision. Double
vision is caused when the two eyes do not align, or work together and
one eye actually turns out, in, up, or down compared to the fellow eye.
The overall encompassing term for this is strabismus. The
disorientation from double vision will frequently trigger dizziness and
balance problems. Treatment is with lenses, prisms, therapy, partial
occlusion (the “spot patch” – please see the web section on double
vision), and rarely surgery.
Ambient Visual Disorder
The ambient visual process frequently becomes dysfunctional after a
neurological event such as a Traumatic Brain Injury (TBI) or Cerebral
Vascular Accident (CVA). Persons can often have visual symptoms that
are related to dysfunction between one of two visual processes: ambient
process and focal process. These two systems are responsible for the
ability to organize oneself in space for balance and movement, as well
as to focalize on detail such as looking at a traffic light.
Distortions of the spatial system may cause an individual to misperceive
their position in the environment. This in turn can cause dizziness
and balance problems with the person showing a tendency to lean to one
side, forward and/or backward. Treatment is with specially designed
prisms and partial selective occlusion. These techniques work
effectively in conjunction with physical and occupational therapy
attempting to rehabilitate weight bearing for ambulation.
Eye Movement Disorders
Eye movement disorders typically show up as instability of visual
gaze (nystagmus), jerkiness of pursuits (eye tracking), or jerkiness of
saccades (visual scanning). Eye movement disorders may be congenital,
or acquired. When acquired, some of the typical causes are brain
injury, stroke, vestibular dysfunction, multiple sclerosis, and other
neurological disease or disorder. Sometimes, an eye movement disorder
can occur for no apparent reason, termed idiopathic.
When there is an acute adult onset of nystagmus the brain does
not register that it is the eyes that are shaking. Rather, the brain
interprets that it is the world and objects in it that are moving. This
is called oscillopsia and will frequently cause dizziness and balance
Treatment is first aimed at correcting (if possible) the
underlying cause for the nystagmus, or other eye movement disorder.
Concurrently, the following neuro-optometric rehabilitation approaches
may be helpful. If there is diplopia, then work with prism, and/or
partial selective occlusion is indicated. Visual exercises may also
help expand the range of single binocular vision. Head position and
direction of gaze may help compensate for the oscillopsia by finding a
null point where the nystagmus is decreased. Partial selective
occlusion can be helpful where (typically) the nasal or temporal aspect
of the lenses in eyeglasses are partially occluded with tape. A
centimeter or less is usually sufficient. Nasal occlusion helps improve
peripheral ambient vision, and temporal occlusion helps block
peripheral stimulation. Low amounts of base-in prism (typically 1½ to 2
prism diopters) can help stabilize peripheral vision and help the