Sex differences in how we move our eyes ... wink, wink

I knew that men and women look at different things and suspected they sometimes look differently at things. But it was a surprise to learn that men and women move their eyeballs differently as well, in a fundamental neurological way.

Eye movement tracking may be a niche, but that's what's on the menu today at Brainwoosh.

Why guess when we can measure?
Diagnosing brain disorders often feels like detective work—relying on symptoms that can be tricky to interpret. That’s why scientists are on the hunt for objective biological markers to help take the guesswork out of neurology. One promising area of brain research is eye movement as a diagnostic tool.

Eye-tracking technology has the potential to be a diagnostic tool for a wide range of conditions. It plays a significant role in detecting Parkinson's disease by identifying abnormalities in smooth eye movements, which are linked to disease severity. These movements can act as biomarkers for disease progression.

Traumatic brain injury also impairs eye movement, and eye-tracking can detect these issues. For athletes with sports-related concussions, this technology provides a non-invasive way to track brain function, cognitive deficits, and indicators of recovery.

In the case of Alzheimer’s disease, eye-tracking may offer a non-invasive method for early detection. Similarly, eye-tracking can be used to assess conditions like schizophrenia, where eye movement abnormalities can point to neuroanatomical features of the disease.

For mental health disorders like depression, post-traumatic stress disorder, and autism spectrum disorder, eye-tracking can provide biomarkers that improve diagnosis. It can detect patterns in gaze and eye movements that reveal cognitive and emotional issues.

One big problem? Most medical research has historically focused on men, meaning our diagnostic tools aren’t always tailored to women’s biology - and the not-so-small physiological and hormonal differences between sexes.

Ignoring these differences and just using the same test and same numbers for both men and women can lead to misdiagnoses and delayed treatments in women.

So, if we want medicine that works for everyone - and that we do - we need to collect more data specific to female biology. In other words, we need basic data for men and for women.

Eyes: The windows to the brain
Our eyes are not an organ in itself. It is the frontmost part of the brain that shoots forward to the eye sockets during development.

The way our eyes dart around isn’t random—it’s controlled by complex neural circuits that can reveal a lot about brain function.

However, despite knowing that both age and sex can influence eye movements, scientists have often lumped everyone together in studies, regardless of age and gender.

That’s a problem because aging is known to slow down certain eye movements, and early research suggests that men and women may have different visual processing patterns.

Young and old people see the world differently.
Well, older people see it more slowly and a bit less smoothly. Age-related changes in eye movement are well-documented, showing slower saccades and reduced tracking accuracy in older people.

Saccades are the rapid eye movements we make when shifting focus from one point to another. It happens automatically, like when we read, look around a room, or follow a moving object. Instead of gliding smoothly, the eyes jump in small, quick steps because the brain constantly adjusts vision to create a clear image.

Visual tracking accuracy is how well your eyes can follow a moving object smoothly and precisely. If your tracking is good, your eyes stay locked onto the target without losing focus. Think of it like following a fast-moving ball in a game—your eyes should smoothly trace its path rather than lagging behind or making jerky movements.

Understanding these differences isn’t just interesting—it could help distinguish normal brain aging from signs of neurological disease.

Despite the findings of age differences, there is a lack of studies examining sex differences in eye movement.

Men and women see the world differently.
Well, that is not a surprise. But that is not just a cultural difference, but also a neurological one definitely is.

Past research shows that men may have quicker reflexes in tasks requiring hand-eye coordination, while women rely more on landmarks for navigation (perhaps explaining why dads refuse to use GPS).

Some past studies found sex differences in gaze duration and scanning behavior, Other studies even suggest that women naturally pay more attention to people’s left eye when recognizing faces.

The big questions:

Is the difference between the sexes so big that it should be taken into account when measuring eye movements as part of diagnostics for a neurological disease?

Big data, big discoveries
In this study, data from 804 clinics using high-tech eye-tracking systems were reviewed. 23,557 participants ranging from age 6 to 80 completed six tests measuring how well their eyes tracked moving objects, how fast they shifted focus, and how stable their gaze remained.

The massive amount of data on eye movements was then divided into sub-groups based on both age and sex. It showed what has already been established, that changes in eye movements develop with age. That was used to benchmark how eye movements change across the human lifespan as a biomarker.

But it also showed that within the same age group, men and women had different patterns of eye movement for every one of the six tests. That's something, and yes, the difference is big and should be accounted for when testing eye movements.

How these differences come into good use ..
The findings add to the growing evidence that men and women don’t process visual information in the same way. This could have major implications for diagnosing neurological disorders.

Being an accessible part of the brain, eye-tracking technology has the potential to serve as a non-invasive tool for detecting neurological conditions, particularly when sex-based differences can be taken into account.

A simple eye-tracking test could one day reliably flag early signs of conditions like Parkinson’s or Alzheimer’s in men and women. Imagine what a difference that would make.

About the scientific paper:

First author: Frederick Robert Carrick, USA
Published: Brain Sciences, December 2024
Link to paper:  https://www.mdpi.com/2076-3425/14/12/1288