Optimizing Vision in Parkinson’s Disease
Vision is a capability that most of us take for granted. Did you know that ⅔ of the brain’s mass is dedicated to processing visual information?! Take a second and think about it… What activities do you do on a regular basis that don’t involve your vision? (Sleeping is about the only one I can think of!)
How does vision specifically relate to Parkinson’s Disease?
More than 75% of people with PD report experiencing at least one visual symptom!
Dopamine is present in the visual system! Some cells within the retina use Dopamine to communicate. Therefore, the general lack of Dopamine associated with PD may contribute to visual complaints and symptoms.
The eyes are muscles too! If you exercise the rest of your body, why not your eyes? Just like any other muscle, the eyes require range of motion or movement for scanning the environment, motor control, and coordination.
Visual deficits alone are strongly associated with postural instability. For those with PD and balance impairments, visual input is relied on even more heavily for stability. If balance and vision are both impaired, then postural instability is affected even more, and thus the risk for falls is also greater!
Visual symptoms in Parkinson’s Disease
Central and color vision abnormalities – may be described as:
Blurred vision
Colors appear “washed out” and less vibrant
Difficulty seeing in twilight hours or when raining
Ocular surface irritation – caused by poor tear production and reduced blinking response as a result of PD, with symptoms including:
Dry eyes
Irritation (gritty / sandy sensation)
Burning
Redness
Crusting on the lashes
Eyes “stuck shut” in the mornings
Sensitivity to light
Decreased contrast sensitivity or decreased ability to detect subtle differences in shading and patterns – for example:
Difficulty seeing in dim lighting
Difficulty discerning where one step starts and one step ends when ascending or descending stairs
Diplopia or double vision
Convergence insufficiency or decreased ability to adduct (“cross”) the eyes and maintain fusion/alignment of the eyes while focusing on a near target, often described as experiencing the following symptoms:
Blurred or double vision
Headaches
Eye strain
Difficulty reading
Impaired visual processing
Impaired depth perception (most common complaint!)
Impaired object perception, such as difficulty identifying overlapping objects and/or impairment in mental ability to rotate objects
Impaired visuospatial construction, in which copying and recalling complex figures becomes difficult
Impaired motion perception, with difficulty accurately judging the direction and/or speed of a moving object
Impaired face and emotion recognition
Peripheral vision deficits – as compared to other disorders, these deficits may present as distractibility by visual information in the periphery rather than loss of peripheral vision
Visual hallucinations
Blepharospasm or the forceful contraction of the eyelid
Apraxia of eyelid opening or impaired motor command to open the eyes
Vertical eye movement limitations
Each of these visual abnormalities alone are typically mild and subtle, but when they occur in combination (especially in conjunction with balance deficits), the functional impact can be significant.
What should I do now to optimize my visual skills?
Maintain routine annual ocular health and acuity assessment with your optometrist and/or ophthalmologist
Ensure your eyeglasses or contact lenses are corrected for your best possible acuity
Treat ocular surface issues to protect the eyes and optimize visual clarity
Keep your primary care physician, neurologist, and/or movement disorder specialist updated on any visual changes or new symptoms
If visual changes or symptoms are present, consider a referral to a neuro-ophthalmologist
Request a script from your physician for occupational therapy
Remember, the earlier these visual symptoms (or any PD symptoms for that matter!) are identified and treated, the greater the improvement in quality of life!