How Parkinson’s Might Affect Our Vision, Depth Perception, and Spatial Awareness
You’re riding in a car, and suddenly a vehicle in front of you slows down—or one zooms past you—and it feels like it appeared out of nowhere. You startle. Your heart jumps. You flinch so hard the driver freaks out.
For me, this happens much more when I’m a passenger than when I’m driving. It’s like my brain wasn’t expecting something to happen, so when it does, I overreact. I hadn’t really thought about it until I visited the Shaikh Parkinson’s research lab at the Cleveland VA last week and spoke with Dr. Aasef Shaikh, a movement disorder specialist and Parkinson’s researcher and one of his research fellows studying how Parkinson’s affects the way we see and interpret the world around us.
Dr. Shaikh’s lab made me think of Back to the Future—as if Doc Brown had ditched the DeLorean to help Marty McFly battle Parkinson’s instead of time travel. It’s full of all sorts of cool motion capture gadgets and eye-tracking machines. Dr. Shaikh is just as passionate about finding the solutions, often sharing his ideas in a way that assumes I am smart enough to keep up with all the thoughts and ideas going through his head. I loved it!
Twitchy is not fun to have as a passenger while you are driving.
👁️ Parkinson’s May Change How the Brain “Sees” the World
Dr. Shaikh explained that in people with Parkinson’s, the brain may rely more on what it expects to see than what it’s actually seeing through the eyes in real time.
That means your brain might “autopilot” through a familiar scene—until something unexpected appears, like a car passing or a sudden stop. The result? You’re startled, thrown off, and your body reacts late or incorrectly. He’s currently exploring whether deep brain stimulation (DBS) might help correct this mismatch between sensory input and brain expectations.
🚪 Freezing, Doorways, and Optical Flow
In addition to visual misinterpretation and startle responses, Dr. Shaikh’s research also made me think about something else many of us with Parkinson’s experience: freezing of gait, especially at thresholds like doorways or narrow spaces.
This might be related to something called optical flow.
🌀 What is Optical Flow?
Optical flow refers to the way our brain processes movement through space based on how visual information flows across our field of vision. When you walk forward, for example, the environment appears to move past you in the opposite direction—walls, door frames, furniture all shift across your retina in a predictable way. This flow helps your brain determine speed, direction, and spatial orientation.
🚫 When Optical Flow Gets Disrupted
In people with Parkinson’s, this system can misfire. The brain may struggle to interpret visual motion correctly, especially during transitions—like walking through a doorway. Your eyes are telling you one thing, but your brain doesn’t process the information fast enough or accurately enough. The result? Your body hesitates. You freeze.
It’s as if your internal GPS loses signal for a moment—you’re still moving, but your brain isn’t sure how or where to go.
This is especially true when:
The lighting changes suddenly (like going from a bright hallway to a dim room)
The visual scene becomes crowded or cluttered
The threshold is narrow or unexpectedly complex
It’s not always anxiety or distraction—it may actually be a delay or mismatch in how your brain is interpreting visual motion.
Sometimes Twitchy has problems with freezing gait
🧠 What the Research Says
Dr. Shaikh’s lab has published several studies on this. Two stand out:
1. Visual Search and Eye Movement Changes
People with Parkinson’s:
Take longer to find specific objects in cluttered scenes
Make fewer sweeping eye movements
Show more small, rapid eye movements (a sign of visual confusion or overcompensation)
2. Reduced Contrast and Motion Perception
As PD progresses, people may:
Struggle to see low-contrast or moving objects
Have a harder time walking in crowds, driving, or navigating stairs
Be more affected in dim light or visually complex environments
Driving has become very stressful for Twitchy.
🧩 Why You Keep Losing Stuff (And Struggle to Find It)
This visual confusion might also explain why so many of us lose things—even when they’re right in front of us. Your keys, your glasses, your phone… If they’re not where your brain expects them to be, your eyes may simply pass over them. Instead of processing what’s actually there, your brain fills in the gaps. It’s frustrating—but understanding this might help. Try placing frequently used items in consistent, well-lit locations, or using bright, high-contrast colors to draw attention to them.
Twitchy gets frustrated because he is always losing his phone and his glasses…
💬 What the Community Is Saying
After posting about this in theParkinson’s Fight Club Facebook group, I was amazed at how many people resonated with this experience. Some shared that driving had become too overwhelming; others said they startled easily as passengers, especially when not focused on the road.
A few described challenges with stairs, escalators, or just walking through busy spaces. Many didn’t even realize these issues could be related to Parkinson’s—they just assumed it was anxiety, age, or vision changes.
One member said it perfectly:
“It’s like being half a second behind real life—like your brain is buffering.”
Twitchy misjudged that last step…
🏠 Why This Matters
This isn’t just about driving. These subtle visual changes can impact:
How safe we feel in crowds
How well we navigate new environments
Our ability to multitask visually or react to sudden movement
Whether we can find things—or avoid bumping into them
And more importantly, they can increase fall risk, reduce independence, and create unnecessary frustration.
💡 What You Can Do
👁️ Practice intentional focus—don’t rely solely on reflexes
💡 Improve lighting and reduce clutter in your home
🎯 Use visual cues (like contrast or labels) for key items
🤝 Share your experience—others may be dealing with the same thing and not even know why
📚 References
Beylergil, S. B., Kilbane, C., Shaikh, A. G., & Ghasia, F. F. (2022).Eye movements in Parkinson’s disease during visual search. Journal of the Neurological Sciences, 440, 120299. 🔗 https://doi.org/10.1016/j.jns.2022.120299
Beylergil, S. B., Shaikh, A. G., & Ghasia, F. F. (2020).Severity‐dependent effects of Parkinson’s disease on perception of visual and motion contrast. Movement Disorders, 35(11), 1992–1999. 🔗 https://doi.org/10.1002/mds.28258
