Normal aging affects your vision and eyes including cataracts, macular degeneration and glaucoma. People with Parkinson’s disease also have a variety of complaints regarding their vision. These complaints include trouble reading, double vision and dry eyes. Not only can visual disturbances interfere with reading or driving, they can worsen walking or balance problems, and even contribute to hallucinations.
Good news: These issues don’t affect every person with PD, but it’s important to recognize these issues and the variety of ways to treat them.
Eye Movement Problems with PD
There are three fundamental types of eye movements.
- Pursuit eye movements: When the eyes follow or pursue a moving target in the horizontal or vertical plane.
- Saccadic eye movements: Rapid eye movements where the eyes quickly jump to a new target. When reading, the eyes need to jump from the end of one line and to the beginning of the next.
- Vergence eye movements: When the target comes towards or away from a person, the eyes must move slightly together, or converge, to keep the target clear.
With PD, the saccadic movements tend to slow down, which means that reading can be difficult if the eyes are unable to find the correct place on the next line. If a person has Levodopa-induced dyskinesias, the saccades can become fast and erratic.
With PD, problems with vergence eye movements can cause difficulty in moving the eyes together. This is called convergence insufficiency, which can cause double vision and can also affect a person’s ability to read.
Managing Eye Movement Problems with PD
If you are experiencing visual changes, it may be time for a lens prescription adjustment, which is normal as we age. See an ophthalmologist or optometrist to rule this out. If they cannot solve the problem, ask for a referral to a neuro-ophthalmologist and/or movement disorder specialist.
Neuro-ophthalmologists bridge the gap between ophthalmology and neurology by diagnosing and treating the vision issues with neurological diseases.
If an eye movement abnormality is found, you may be prescribed two pairs of glasses, one for distance and the other for close activities and reading. This often works better than bifocals. If you are found to have convergence insufficiency, you may be prescribed glasses with prisms. Prisms help to bend light to the proper focal point on the retina when the eyes are not able to achieve this on their own.
Dyskinesia can also affect the eyes and cause blurred vision. If someone is experiencing dyskinesia in other parts of the body, this might be the reason for visual disturbances. Dyskinesia typically happens in the “on” state — when Parkinson’s symptoms are otherwise well-controlled, some people experience worsening of vision as medication starts to wear off and Parkinson’s symptoms return. Medication adjustments may be the solution.
If you’re experiencing changes in your sight, don’t automatically blame it on age or Parkinson’s. Ask your doctor what could be causing your symptoms and what treatments are available. Don’t hesitate to ask for a neuro-ophthalmologist if the symptoms persist.
Next week’s blog post will feature more information on other eye disorders due to PD, and the related treatments.
References:
https://www.apdaparkinson.org/what-is-parkinsons/symptoms/eye-vision-issues
www.michaeljfox.org/foundation/news-detail.php?ask-the-md-vision-and-parkinson-disease