Double vision
Double vision resulting from reduced dopamine levels in the brain may respond well to standard Parkinson’s medications. Rest is also helpful, so if double vision occurs when reading, it may be a good idea to have a break and rest the eyes for a while. If medication and rest do not help, special lenses may be prescribed by your optician.
Occlusion, the covering of one eye, is another possible solution because double vision can not occur when only one eye is being used. Special translucent patching materials are available to occlude one eye. They are barely noticeable, and in some cases only a part of a glasses lens needs to be covered so that the rest of the lens permits clear vision.
Blurred vision and difficulty focussing
Some Parkinson’s medications, in particular anticholinergic medications, can cause blurred vision and difficulty focussing. Such medications may only affect vision when a course of treatment starts and vision may improve after a while. They can also affect vision if an established dose is altered.
If blurred vision does not improve - or worsens - over time, your doctor may reduce your medication. Reading glasses, if worn, may also be modified successfully, especially for those who are on an existing course of medication that is working well.
Difficulty moving the eyes or difficulty in focusing on moving objects
This may be particularly noticeable when following a fast-moving object such as a vehicle or ball. The eyes may move slowly and jerkily. This can be a result of the reduced or slow movement found in Parkinson’s and there are medications available used to treat such motor difficulties.
If significant difficulties are experienced in moving the eyes up and down you should discuss this with your doctor because it is a common symptom of Progressive Supranuclear Palsy (PSP), a form of Parkinsonism.
Dry eyes
Blinking is necessary to keep the front of the eye moist and to maintain the tear film that coats the front of the eye surface (the cornea). Blinking also acts as a ‘windscreen wiper’ for the eyes, clearing away any debris or dust. If blinking is reduced, vision may be impaired and the eyes can become dry and sore.
Special eye drops, often known as artificial tears, are available from pharmacies to lubricate the eyes and reduce discomfort. There are many varieties available so you may need to experiment to find the type that works for you. It is best to use drops that are preservative-free. Using an eyewash may also help to flush out debris and moisten the eye.
Hot, dry, smoky atmospheres can irritate the eye and are best avoided. If the eyes become particularly red and sore you may have developed conjunctivitis, which needs to be treated with antibiotics, so do check symptoms with your doctor.
Involuntary closure of the eyelids (blepharospasm)
Treatment of blepharospasm can be tricky because levodopa may, in fact, be the cause of it. In other cases, however, levodopa can improve eye spasms. Your doctor may therefore need to adjust your medication.
Rubbing the eyelids can help in mild cases, and sometimes an injection of botulinum toxin may also be helpful.
Deterioration in visuo-spatial orientation
If your ability to judge the space around you or objects deteriorates an occupational therapist can help. Moving around, particularly through narrow spaces, may become difficult and an occupational therapist can re-organise rooms to make navigation as easy as possible. Some people find it helpful to move around by touching objects in their path or by feeling the sides of narrow doorways.
Hallucinations and illusions
Particularly in the later stages of Parkinson’s, some people see objects, people or animals that are not really there (hallucinations), or they misinterpret real objects (illusions).
Hallucinations may be in black and white or in colour, still or moving. They can be very disturbing for those who see them. Parkinson’s itself is the most likely cause, although some anti-Parkinsonian medications can also be responsible, particularly in older people who already have some memory problems. Poor eyesight, infection and other illnesses may also cause hallucinations, so all should be investigated when diagnosing. To ascertain if your medication is responsible, your doctor may try adjusting your medications. Sometimes, no specific action is required if the hallucinations are not distressing; simple reassurance that they are harmless may be all that is needed. If Parkinson’s is the cause neuroleptic medications, such as quetiapine, risperidone or olanzapine may be prescribed. These medications suppress hallucinations without exacerbating other symptoms. However, such medications can have side effects so it is important to discuss any changes or new symptoms with your doctor.1
Illusions, or visual misinterpretations, are often not linked to Parkinson’s and may have another underlying cause such as poor eyesight. If their onset is sudden then an infection or other illness may be the cause – this may be referred to as delirium. You should always tell your doctor if you are experiencing illusions or hallucinations.
Glaucoma
The effectiveness of medications for glaucoma may be reduced by some anticholinergic medications, and levodopa. For people with open-angle glaucoma, these medications should be used cautiously with close monitoring because they could cause increased pressure within the eyes. Anticholinergics and levodopa are not recommended for those who have closed-angle glaucoma. They dilate the pupil (mydriasis) and could cause blockage of trabecular meshwork, that is the network of fibres that is responsible for draining the fluids from the eye.
If you have glaucoma it is helpful for your doctor and opthamologist to work together in prescribing and monitoring medications. Always remember to tell your doctor that you have glaucoma when your Parkinson’s medications are being reviewed.
Excessive watering of the eyes
Excessive watering is usually a response to irritation, which is often eased by using eye lubricants. If the watering does not settle with such treatment, your neurologist should be informed as it may be appropriate to be referred to an ophthalmic surgeon for an opinion. Based on the few new reports published 2, botulinum toxin A injections into the lacrimal (tear) gland may also help.
Tired eyes
Management of tired eyes is simple: take regular rest breaks from visual activities. For example, after 20 minutes working at a computer or reading a book, look into the distance, perhaps out of the window, for a minute. Also, have regular reviews by an optometrist to correct any ophthalmic dysfunction and always ensure you have good light when reading.
Colour vision and contrast sensitivity
Levodopa and other Parkinson’s medications may help with these problems and your doctor will be able to advise you on this.
