Zietchick Research Institute: Learn about eye problems associated with Parkinson’s Disease

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Parkinson’s disease is a progressive deterioration of brain function, mostly occurring in people over the age of 60.  Men are affected more often than women.

In all, over 200,000 people each year are diagnosed with this condition. Zietchick Research Institute explains that the underlying problem of this disorder involves the inability of nerve cells to produce enough quantity of the neurotransmitter known as dopamine.

Because dopamine helps control motor function, a deficiency of dopamine in the brain, such as occurs in Parkinsons, causes significant problems with movement.  Thus, the symptoms that we most commonly associate with Parkinsons are motor problems such as tremor, slowed movement, rigid muscles, problems with posture and balance, speech changes and loss of automatic movements (such as less ability to blink or to swing arms when walking).

Zietchick Research Institute wants to increase awareness that the eyes are frequently affected by this disease. In fact, many eye problems occur in early stages of the disease, even before the diagnosis of Parkinson’s has been determined. The vision researchers at Zietchick read over the article “Early ophthalmologic features of Parkinson’s disease: a review of preceding clinical and diagnostic markers” by Turcano, et al which has been published in Journal of Neurology (September 2019).

The authors of the literature review report that problems with color vision and contrast sensitivity are not uncommon and that these problems may occur due to decreased production of dopamine by neurons in the retina, the photosensitive layer of the eye.  When color vision is affected in this disease, the hues of blue and blue-green become most difficult to recognize.

When contrast sensitivity is affected, the patients may have difficulty in distinguishing  objects from background. This can especially be troublesome in low light circumstances such as driving at night. Patients need to be made aware of this so that they can adjust their driving habits accordingly.

Many other types of eye problems also occur, both from the disease itself as well as from the treatment of the disease.  For example, blurry vision, dry eye and double vision are frequently reported.  These symptoms may be due to difficulty in blinking or irregular eye movements caused by the disease.

Blinking and eye movements depend upon the motor activity of the eye lid and eye muscles. Therefore, it is not surprising that Parkinson’s Disease, known to affect movement of other body parts, would also involve movement of the eyes. Abnormalities in eye movement can affect both fast eye movements (known as saccades) or slow eye movements (known as pursuits). Double vision can occur to a  failure of the eyes to coordinate with one another.

Alternatively, these symptoms may be the result of the medications, such as anticholinergics, that are used to treat the disease. Dry eye and blurry vision are common side effects of anticholinergics. Zietchick Research Institute also notes that visual hallucinations can occur.

When hallucinations occur, they are not directly to problems in the eye. They are more likely due to problems in the visual cortex—the part of the brain that play a role in vision. It is important that patients with Parkinson’s Disease tell their eye doctors if they experiencing any problems with vision in order to receive proper treatment.