Parkinson’s disease affects movement, and this includes movement of the eyes. As such, eye problems are not unusual for people with Parkinson’s, especially as the condition progresses. But not all eye problems are related to movement, and some may be caused by Parkinson’s medication rather than the condition itself.
Eye problems and difficulties include:
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double vision –reduced dopamine levels in the brain disrupts the chemical messengers to the eye and other parts of the body and can lead to difficulty in moving the eyes. Fatigue and poor vision can also contribute, resulting in double vision. Eyes should ‘track’ and move in alignment - for example, when going from side to side or up and down around a page. This allows the images from the two eyes to be fused together in the brain so that we see only one image. If ‘tracking’ is poor more than one image may be seen at a time. For some people this happens only when looking in certain directions, or when reading words in the distance. This is known as ‘convergence insufficiency’. People who have double vision often say that words are blurred or start to run together, and their eyes tire easily
- (also known as blepharospasm) - occurs when the muscles that control eyelid movement go into spasm [see also Cramps & dystonia]. When these muscles rapidly contract the eyelid closes repeatedly causing excessive blinking or twitching. Eyelids may even completely close for a short time. Whilst levodopacan improve eye spasms in some people, it can actually cause blepharospasm in others
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deterioration in visuo-spatial orientation – the ability to judge the space around you or between objects may deteriorate making moving around difficult. This type of problem tends to be worse in those people whose Parkinson’s affects the left side of the body
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hallucinations and illusions - may occur, especially in late stage Parkinson’s, as a result of either the condition itself or anti-Parkinsonian medications, or due to other unrelated causes such as infection or other illnesses
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glaucoma (high fluid pressure in the eye) – whilst Parkinson’s does not actually cause this condition, anticholinergic medications may reduce the effectiveness of glaucoma-treating medication
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excessive watering of the eyes – people with Parkinson’s can experience this for several reasons; one being infrequent blinking due to impaired reflexes. Poor corneal wetting resulting from infrequent blinking stimulates the lacrimal (tear) gland to produce excessive lacrimal fluid. However, this does not improve irritation of the surface of the eye
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tired eyes - this is a common symptom in Parkinson’s, as well as many other neurological and non-neurological conditions. Reading, for example, may become difficult. There are several possible causes, the most common of which is problems with focussing and convergence insufficiency (an inability of the eyes to converge on close objects) due to rest tremor and dyskinesias
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colour vision and contrast sensitivity – due to a retinal dopamine deficiency, people with Parkinson’s may find it hard to distinguish between shades of the same colour, particularly blues and blue/greens. Some people also experience difficulty defining images on a background of similar shades or colours and reading fine print, particularly in low light levels. Parkinson’s causes a progressive loss of dopamine producing cells, including in the retina (the lining of the back wall of the eye that transmits images to the brain via the optic nerve) as well as other areas of the visual system.
Eye problems are not always directly related to Parkinson’s and may be a symptom of another condition. Age-related deterioration or being tired can make problems worse. If you have any problems with your eyes, see your doctor to determine if Parkinson’s is the cause or even a contributing factor. If necessary they will refer you to an ophthalmic optician or ophthalmologist (a specialist in the workings of the eye, eye conditions and corrective measures). They will determine whether or not glasses may help, and be able to rule out or diagnose other eye conditions.
Eye problems can impact considerably on quality of life, so it is important to establish the cause of any problem or discomfort as soon as possible. Unnecessary surgery or other intervention can be avoided if Parkinson’s-related problems are identified early.
