Vision changes in Parkinson’s disease
Parkinson’s disease (PD) is a neurodegenerative disorder. It causes tremors, stiffness, slow movement and other health issues. It can also affect eyesight, causing eye movement problems and double or blurry vision. Dry eyes, color vision changes and visual hallucinations can also occur.
Parkinson’s disease damages cells in a part of the brain called the basal ganglia. This region coordinates movement. It also helps regulate levels of a chemical messenger called dopamine. As PD progresses, the decreased dopamine disrupts body functions, including those of the eyes and vision. As a result, Parkinson's and eye issues often go hand in hand.
Common eye symptoms in Parkinson’s disease
Many people find that Parkinson’s disease affects eyesight. Four out of five people with the condition report difficulty with daily visual tasks. These include reading, driving and navigating spaces.
PD can cause:
- Double vision
- Dry eyes
- Impaired color perception
- Issues with eye control
Symptoms can be due to the condition or occur as side effects of medication.
Parkinson's disease and the eyes are closely linked. The retina — the light-sensitive layer at the back of the eye — relies on dopamine to function properly. As dopamine levels drop in PD, retinal cells degenerate.
Vision changes often go unnoticed until they interfere with daily life. Recognizing and managing vision changes early is critical.
Parkinson's disease eye symptoms may include:
Double vision (diplopia)
Double vision, or seeing two images instead of one, occurs when the eyes do not align. This condition is called convergence insufficiency. Normally, both eyes turn inward to focus on close objects like books. PD weakens the muscles controlling this motion. Because of this, double vision is common with Parkinson's.
Symptoms of double vision include:
- Overlapping text while reading
- Headaches from eye strain when doing close-up tasks
- Difficulty judging distances when walking or driving
Neuro-ophthalmologists are doctors who specialize in vision problems caused by nervous system issues. They can help guide your treatment and recommend support from other health care professionals.
Treatment for double vision includes:
- Prism lenses – Prism glasses have special prism lenses that bend light to align images
- Vision therapy – Exercises to strengthen eye coordination
- Temporary eye patching – Eye patches that cover one eye during tasks like reading and cooking
To build your support team, your doctor may refer you to low-vision specialists, occupational therapists and other care providers.
Dry eyes
Reduced blinking is a common sign of Parkinson’s disease. Fewer blinks can lead to dry, irritated eyes and an unstable tear film. Dry eyes can also be caused by certain medications used to treat PD.
Dryness can lead to excessive tearing as the eyes try to compensate. Due to this, Parkinson's often causes watery eyes as well.
Unstable tear film can result in blurry vision. Clarity may improve temporarily with blinking. But vision will become blurry again when new tears evaporate.
Reduced blinking may be the result of:
- Dopamine loss – Involuntary movements, such as blinking, become less frequent with less dopamine.
- Facial slowing (bradykinesia) – Facial movements slow down with PD, including blinking.
- Nervous system dysfunction – Parkinson's disrupts the autonomic nervous system. This system controls functions like heart rate and blinking.
Symptoms of dry eyes include:
- Irritation and gritty sensations, as if sand is in the eyes
- Blurry vision that temporarily clears with blinking
- Redness or crusty eyelid margins from inflammation (blepharitis)
- Watery eyes
Treatment for dry eye may include the use of:
- Artificial tears – Using artificial tears regularly can help keep the eyes moist and reduce irritation.
- Warm compresses – Applying warm compresses can help dissolve blockages in oil-producing glands. It can also relieve blepharitis symptoms and improve tear quality.
- Humidifiers – Adding moisture to dry indoor air can ease symptoms.
Blurry vision
Blurry vision in people with PD often fluctuates. This can make tasks like reading labels or recognizing faces frustrating. Blurry vision has several causes:
- Dry eyes – Uneven tear film disrupts light entering the eye.
- Medications – Anticholinergics reduce tear production. Examples include trihexyphenidyl (Artane) and benztropine (Cogentin).
- Focusing issues – Convergence insufficiency makes near vision blurry.
Symptoms of blurry vision include:
- Difficulty reading words up close or at a distance
- Trouble navigating a space
- Increased tripping due to problems with depth perception
Treatment for blurry vision with PD may include:
- Avoiding bifocals, which can worsen depth perception
- Improving contrast, such as using bold black pens on white paper for writing
- Medication adjustments
Color vision changes
Dopamine in the retina plays a role in your ability to distinguish colors. As PD progresses, dopamine neurons in the retina decrease. This can cause color perception to fade.
Symptoms include:
- Trouble telling apart blue/green shades (difficulty matching clothing colors)
- Reduced vibrancy seen in outdoor colors (grass appearing dull)
- Trouble reading colored text on a similarly toned background
Color vision changes may appear even before motor symptoms. Researchers have suggested that this decline may be an early warning sign of PD.
Decreased contrast sensitivity
Reduced contrast sensitivity is a common vision issue with PD. This problem stems most notably from the loss of dopamine in the retina and brain, which is crucial for visual processing. It affects how well people with PD can distinguish objects from their backgrounds.
This can make low-light conditions very challenging. While high-contrast vision might appear normal, low-contrast vision is often impaired. This can lead to difficulties with tasks like reading and cooking. Recognizing faces in dimly lit spaces can also be a struggle.
Visual hallucinations
Up to 25% of people with PD experience visual hallucinations. These range from seeing shadows and objects to complex scenes. They can be due to:
- Medication side effects – Dopamine agonist medications may overstimulate visual pathways.
- Retinal dopamine loss – The decreased dopamine can disrupt visual processing.
- Cognitive changes – Later stages of the disease can affect brain regions that affect thought processes.
Symptoms include:
- Brief flashes of light or patterns
- Seeing animals or people who vanish when approached
- A feeling that someone is present in peripheral vision
Treatment and management for hallucinations may include:
- Medication adjustments – Adjusting medications such as dopamine agonists
- Use of nightlights – Adding soft lighting to reduce shadows
- Focusing on distractions – Using television or another activity to distract yourself
- Lifestyle changes – Implementing good sleep habits, avoiding caffeine and alcohol, and relaxing before bed
Eye movement issues in Parkinson’s
Eye movement issues in PD are common. This is because dopamine is crucial for coordinating movements. As a result of dopamine loss, tasks like reading, walking and driving become more challenging. Eye movements that are affected include:
Rapid eye movements
These movements, called saccades, are quick eye jumps. They are used when reading or scanning a room. In PD, these movements become slower and less accurate. This contributes to difficulty reading, falls and missed steps.
Inward and outward eye movements
These movements, called vergence movements, help the eyes focus on near or far objects. PD weakens this ability, causing depth perception errors. This can cause difficulty with daily tasks. These include climbing stairs or pouring liquids.
Blinking and eyelid issues
Reduced blinking is a common sign of PD and can lead to dry eyes and irritation. Blepharospasms (eyelid spasms) can also occur. In fact, eye twitching with Parkinson's is not uncommon. Apraxia of lid opening (difficulty reopening closed eyes) may also be seen. Botulinum toxin (Botox) injections can relax overactive muscles.
How Parkinson’s medications affect vision
Parkinson's disease medications can improve movement. But the following medications may also affect vision in several ways:
- Levodopa – Levodopa (L-dopa) is a medication that is converted into dopamine in the brain. It may cause visual hallucinations or abnormal, involuntary eye movements called ocular dyskinesia.
- Dopamine agonists – Dopamine agonists mimic the effects of dopamine in the brain. They may have side effects such as visual hallucinations or involuntary eye movements.
- Anticholinergics – Anticholinergics can reduce tremors. But they can worsen dry eyes and cause pupil dilation (which increases light sensitivity). They can also make it more difficult to focus up close.
Some people with PD also have glaucoma. This is a group of eye diseases that damages the optic nerve. For these people, certain medications — including anticholinergics and levodopa — may need to be avoided.
Always inform your eye doctor about any PD medications you take and report any new symptoms. Side effects from medications can vary with each individual. Discuss symptoms with your doctor so they can adjust the dose or switch the medication.
Tips for managing vision changes in Parkinson’s
A neuro-ophthalmologist specializes in treating vision changes in Parkinson’s. Your optometrist or ophthalmologist will check your vision and eye health. They may also test your contrast sensitivity and color vision. Your eye doctor may also perform optical coherence tomography (OCT). This is a test used to detect retinal thinning linked to PD progression.
Management strategies often include:
- Task-specific glasses – Use separate pairs for reading and distance.
- Keeping eyes moisturized – Use artificial tears and warm, moist compresses.
- Optimized lighting – Create a well-lit home environment while reducing glare.
- Improved contrast – Use black and white or other contrasting colors.
- Screen modifications – Increase text size and use "dark mode" settings to ease eye strain.
- Vision therapy – To address convergence insufficiency and other muscle imbalance.
- Lifestyle changes – Maintain a healthy diet and exercise regularly.
Are macular degeneration and Parkinson’s disease connected?
Age-related macular degeneration (AMD) is an eye disease that affects the center of the retina. This region is called the macula. AMD impairs your ability to see the details of what you’re looking at. It is the most common cause of vision loss in adults over 50.
A study in Taiwan analyzed over 20,000 individuals with macular degeneration. It found that the risk of developing Parkinson's disease rose if individuals had AMD, were older than 60 and had one of the following conditions:
- Diabetes
- High blood pressure
- Osteoporosis
People with AMD who were taking specific medications showed a much greater risk of developing PD. These medications included:
- Calcium channel blockers – Typically prescribed for high blood pressure
- Statins – Typically prescribed for high cholesterol
AMD and Parkinson's disease have some similarities in how they affect and damage the body.
They are both degenerative and they both have older age as a risk factor. In addition, the two conditions overlap in the following ways:
- Thinning of the retinal nerve fiber layer (RNFL) – Studies have found that advanced AMD is associated with a thinner retinal nerve fiber layer. Individuals with Parkinson's disease also experience this thinning.
- Dopamine – The retina (affected by AMD) and the brain (affected by PD) both depend on dopamine to function properly.
- Inflammation – Inflammation is an immune response that helps the body remove harmful substances. It also helps heal injured tissue. Several studies have found that inflammation plays a role in the progression of AMD and PD.
- Oxidative stress – Inflammation can cause oxidative stress. Autophagy dysfunction — problems with how the body clears out debris — can also cause it. Oxidative stress is commonly present in both AMD and PD.
When to see a doctor for vision problems
Parkinson's disease does not cause blindness, but it can cause vision issues that affect daily life. These eye problems can be managed with the help of your eye doctor.
Persistent double vision
If you experience double vision, see a doctor if it persists or gets worse. Double vision can be a sign of convergence insufficiency. It can also be caused by dry eye, the need for a new eyeglasses prescription or cataracts.
Your doctor can determine and treat the cause of your double vision. If you notice sudden changes in your vision, seek medical attention urgently.
Sudden vision loss or hallucinations
Sudden vision loss or hallucinations in Parkinson’s disease can happen for a few reasons:
- Medications – Drugs like dopamine agonists may cause hallucinations.
- Disease progression – Brain changes over time can affect vision processing.
- Medical conditions – Stroke may cause vision loss and hallucinations.
- Eye conditions – Acute angle-closure glaucoma due to medications can cause vision loss.
Seek medical attention immediately in case of:
- Sudden vision changes or a dark shadow coming over your vision
- Hallucinations that make daily tasks unsafe
- An onset of confusion, fever, headaches or another medical emergency
- A fall, especially with injury or loss of consciousness
Difficulty with daily tasks
Parkinson's disease can impact daily activities like reading and driving. This is due to blurred vision, double vision, and difficulty focusing. These problems can make it challenging to read or judge distances while driving. It's important for people with Parkinson's to have regular eye exams for optimal vision and safety.
How an eye doctor can help
Regular comprehensive eye exams are crucial for maintaining your independence and safety. During an appointment, your eye doctor can:
- Prescribe prism glasses for double vision
- Recommend separate glasses for near and far vision
- Treat conditions like dry eyes with artificial tears
- Address other vision issues that impact daily activities, like reading and walking safely
Your eye doctor can also coordinate care with your neurologist. Medications can be adjusted if you need treatment for glaucoma or other eye conditions. They can also communicate with your health care team if you experience visual hallucinations.
Parkinson's can affect your eyesight, but advances in treatment offer hope for managing your vision changes.
