World Parkinson's Day: Talking Parkinson's and Vision with Liz.
Eyes on Oxford Optometrist and Optometric Adviser to the Parkinson's Association of Western Australia, Liz Wason, outlines the impact Parkinson's can have on vision and the treatments she commonly uses to help those with Parkinson's manage these effects.
What is Parkinson's?
Parkinson’s is a neurological degenerative condition affecting various body functions especially muscle movement and control. It is caused by reduced Dopamine levels being produced in the mid- brain. By the time symptoms occur, there is already approximately 70% reduction in normal Dopamine levels. Dopamine is a chemical responsible for transporting messages from the brain through the nerves to parts of the body. Low levels means no message, weakened message, or intermittent messages to initiate a body movement or response.
How does Parkinson's affect vision?
The most common and typical effects to the vision system are:
- Reduced blinking rate and tear film irregularity causing dry eye. This can present as gritty eyes, sometimes redness, excessive watering, smeary vision or fluctuating vision.
- Reduced visual awareness in dim or low light conditions caused by the outer retina having less sensitivity because of low Dopamine levels. Often Parkinson's patients will want the lights turned on in the house even during the day to increase light levels for seeing more easily and moving confidently inside.
- Poor eye movements for scanning the environment, reading fluently and looking up & down. This will affect safely moving around both indoors and outdoors, driving awareness and reading or writing speed and accuracy. Having to move the head and body instead of just eyes to look at objects increases the rate of falls and increases effort to complete tasks.
- Eye co-ordination control is typically impaired for holding attention and concentration especially for close tasks such as reading, writing and computer use. This can cause issues such as losing place while reading, having to re-read print, reduced comprehension, loss of enjoyment and extreme effort for these activities.
- Medications prescribed for PD often cause changes to pupil reactions causing slower adjustment for change of focus (e.g. far to near) and from well- lit to darker situations.
Optic nerve function can be monitored as an indicator for progression of PD so digital retinal photos and OCT scans are important tests to be checked regularly.
How can these effects on vision be managed?
Commonly, those with Parkinson's will need:
- Eye lubricants for dry eye.
- Separate near task spectacles with prism to assist eye convergence for improving visual comfort and concentration. Bifocal and multifocal are not recommended due to increased risk of falls associated with slow body movement and posture correction and due to poor eye movements exaggerated by disturbed spatial awareness from the lenses. It is also recommended to avoid tinted lenses for indoors.
- In some cases, special prism lenses can assist posture concerns or improve eye position for specific tasks or hobbies.
It is important that medications are discussed with your Optometrist due to possible side- effects. It is also important that your eye exam is performed during your ON medication time to ensure best outcomes & consistent results are measured.