By Michael C. Schubert, PT, PhD
The vestibular system includes the parts of the inner ear and brain that help control balance and eye movements. If the system is damaged by disease, aging, or injury, vestibular disorders can result. Symptoms of vestibular disorders — which affect about half of the U.S. population — include unsteadiness, dizziness, vertigo, nausea, headaches, hearing and vision problems, and difficulty with concentration and memory.
A common complaint for people with vestibular disorders is that they have difficulty with their vision. They may experience problems focusing on an object or perceive that objects are moving from side to side or revolving around them. They may see their visual field jiggle or bounce during head motion or have double vision. When they hold their heads still, these visual instability problems might resolve.
Many people with vestibular disorders see an optometrist due to their visual symptoms. The optometrist typically conducts an eye exam while the patient’s head is securely braced against a head rest, thereby reducing the head motion and preventing the visual symptom. In a vestibular disorder, the eyes are not the cause of the problem; therefore the optometrist will not identify any eye pathology that would explain their report. Patients may become frustrated hearing the optometrist explain the normal results of their exam, which does not explain their symptoms.
How do vestibular disorders affect vision?
The vestibular system sends a signal through the brain to the muscles of the eyes. The “ear to eye” connection is known as the vestibulo-ocular reflex (VOR). The VOR has a critical role of keeping the eyes still during head motion. This is known as gaze stability. The VOR also sends a signal down to the postural muscles of the trunk/arms/legs, crucial for maintaining balance. Another way to explain this is to consider the video camera. Video cameras have motion stabilizing equipment built into them. This equipment stabilizes the visual world in order to capture a clear visual scene even though natural motions of the hand holding the video camera would otherwise blur the image. In the case of a deficient VOR, the eyes move during head motion, when they should instead be still.
Reading text on a printed page or computer can be difficult for people with an impaired VOR, because the small head motion destabilizes gaze. The result is that words and letters appear to bounce and shift. People with vestibular disorders may also have an illusion of motion in their peripheral vision and have difficulty looking over their shoulder when backing up in a car. These visual distortions may be especially problematic for a person who wears glasses.
The diagnosis of a vestibular disorder relies on a combination of careful history of the problem, physical examination, and a variety of vestibular function tests that are administered and interpreted by trained specialists. It is important to have a correct diagnosis before steps can be taken to treat the condition. The first approach to resolving most of the vision problems arising from a vestibular disorder is to treat the disorder. Depending on the specific diagnosis, treatment may involve vestibular physical therapy, surgery, medication, as well as optometric therapies like corrective lenses and eye exercises. Vestibular physical therapy incorporates specific exercises with the goal to improve gaze and gait instability, reduce head motion-induced dizziness, reduce fall risk, and improve fitness.
To facilitate the recovery process, certain strategies can be adopted to improve tolerance:
- When outside, use high quality sunglasses to reduce glare.
- Minimize visual distractions in the peripheral vision by using sunglasses with side visors.
- Focus attention on a large object a short distance away while walking toward it.
- Use a cane to increase touch cues.
- Ensure home or office lighting is consistent from room to room.
- Many people report increased sensitivity to fluorescent lights. If this is a problem, consider using a small incandescent desk light.
- Reduce home décor that involves a complicated, busy pattern. This might include replacing wallpaper, substituting light-filtering curtains for mini-blinds, and replacing or removing highly patterned carpet.
Vestibular disorders can be disabling and thus tempt those affected to stay home and avoid head motion or visual stimulation. However, this will undermine the brain’s ability to make adjustments and recover. Most vestibular disorders can be treated with options that offer significant relief.
To read the complete article on Vision Challenges or to read more about vestibular disorders, visit the Vestibular Disorders Association website at www.vestibular.org.
For more information locally on any type of Vestibular Disorder, including problems with balance or dizziness, you may contact Poonam McAllister at Central Illinois Institute of Balance by phone: 309-663-4900 or online: www.dizzyil.com. Poonam is specially trained in the evaluation and treatment of balance disorders using a comprehensive approach that looks at the complexities of balance problems in the context of the total patient. Her office is located at 211 Landmark Dr, Suite E-3 in Normal.
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