The Influence of Visual Triggers on Symptoms in Brain Injury and Concussion

By Karen Monet

Stress, both good and bad, is something that we all deal with.  For many, managing stress is possible even though we may need help from supportive family, friends, coworkers, doctors, and therapists. The trauma of a brain injury, however, can cause a drastic change in our health, increasing the stress in our relationships, employment, finances, and lives in general.  What was once manageable, may now be too overwhelming to manage. 

It can be hard to identify everything contributing to this sense of overwhelm.  This article aims to point out some of the environmental influences that may be contributing to stress, and provide suggestion on how to modify these influences so recovery and rehabilitation can be improved.

Too Much Information

Our brains are subject to a non-stop barrage of information – what we are sensing, what we are feeling, and what we are thinking about both. Visual information accounts for approximately 80% of the sensory information we take in, so if the brain is injured and becomes sensitive to visual information, too much energy can be used dealing with the results of this sensitivity, and there may not be enough left to work on recovery.

Tolerance to visual information often decreases following a brain injury and it may be difficult to pinpoint the specific visual information that is uncomfortable and triggering symptoms. Initially following a brain injury, it is recommended to briefly avoid stimulation, bright lights, and computers. Many people are fine to get back to their regular lives shortly after a concussion. But for those who aren’t, changes to the visual environment are necessary to decrease sensitivities and encourage healing.

Visual Stress and Uncomfortable Images:

Visual Stress is the term used to describe the overwhelm (hyper-excitement) the brain experiences in the presence of uncomfortable visual triggers.  Uncomfortable images have been identified as those having a high spatial frequency such as those that are patterned and of high contrast. (Perception. 2008;37(7):1098-113. Uncomfortable images in art and nature. Fernandez D1, Wilkins AJ.) In addition, images that flicker or move quickly have been reported to be uncomfortable in those with hyper-excitable visual cortices (migraine, epilepsy, autism, head injury). (Wilkins et al. 1989 and Kowacs et al., 2004)

Functional magnetic resonance imaging (fMRI) has been used to demonstrate that “Most uncomfortable visual stimuli will reduce the sparseness of neural activity according to models of the visual cortex; and increase the amplitude of the haemodynamic response” (Arnold Wilkins, Discomfort and Hyper metabolism, Project October 22, 2016 ResearchGate)

Simplified, images that our brains find uncomfortable will:

1) increase the density of our brain activity, and
2) increase the energy (blood) sent to the area in response to the visual stimuli.

This increased density and energy can lead to difficulty focusing, headache, and perceptual distortions as the brain is overwhelmed with too much activity in one area.  If the trigger to the hyperexcitement is not stopped and this brain activity and energy is not reduced, the effect then cascades into other areas of the brain.  These same results have been shown using other brain imaging techniques including Near infrared spectroscopy and QEEG, shown here.

I often use the analogy of blushing to explain – when triggered by something embarrassing, our cheeks fill with blood, become red, burn with heat, and the skin can actually sting as the blood makes the area firm.  Until we remove ourselves from the trigger experience and start to calm down, this can be very uncomfortable.  And the same goes for our brain.

So what can be done?

Start by evaluating the visual environment, look for images that are uncomfortable that you avoid looking at.  The idea is to find these items/images and make changes where possible, even if the changes are only temporary until the original environment is more tolerable. A good rule of thumb is things that are similar to those found in nature will be comfortable and anything unnatural will likely be uncomfortable.

And, while wearing dark sunglasses may be a go-to solution, consider this, wearing dark sunglasses will block out almost all the visual information leading to eye strain. This is similar to having to strain to hear something through noise cancelling headphones.

1) Reduce High Contrast Images

Find and remove items in your visual environment with high contrast. This is not just black against white, but also colours that are opposite like red/green, purple/yellow, and blue/orange.  Also remove dark/light contrast images as they have the same effect that black/white has on hyperactivating the visual cortex.  

Difficulty reading is a commonly reported post-concussion symptom.  To reduce the contrast of black text on white paper select a comfortable colour of paper and write on it with a similarly coloured pen or print on it with a closely coloured font.  Reducing the contrast on your computer screen or phones is possible with specific software and apps that tint screens and change font colours.

2) Reduce Patterns

Repetitive narrow patterns like stripes are one of the most uncomfortable images, and the biggest triggers to visual stress.  Look at patterns around you in artwork, clothing, carpets, flooring, fabrics and window coverings. Text is also a pattern. Things that were liked and tolerated before injury may now be causing discomfort simply because of the pattern.  The more these items are present in the visual environment, the more the visual stress accumulates. Change out highly patterned artwork, cover patterned carpets or flooring with solids, soften items with sharp corners and edges with plants, blankets, or curtains. Think soft curves of nature.

A local rehabilitation centre changed their high contrast tile flooring because of complaints from patients who felt uncertain walking on it and afraid they would fall. Similarly, a local physiotherapy clinic with a highly patterned carpet must lay towels over the carpeting to reduce nausea of clients looking down from the therapy beds.

3) Reduce Flicker

Flicker is the on/off presentation of an image. It could be the flicker of a computer screen, fan blade, light reflecting off moving water, images moving past the car window, etc.  Think about how you feel when looking at these flickering images and do what you can to avoid looking at them.  There are specialty filters for computer screens and fanless fans.  As well, there are specific filter lenses that can be worn to reduce the effects of visual images that cannot be changed.

Another source of flicker is lighting, specifically fluorescent.  For those who have experienced a brain injury, sensitivity to this flicker may be heightened and can be perceived even if others around do not notice it. The CFL (compact fluorescent lights) bulbs that were put into lamps and lights when incandescent bulbs were phased out are fluorescent and can be contributing to discomfort. Look instead for dimmable and tunable colour LED bulbs to replace them.  These bulbs can also be used at the office for task and ambient lighting if the overhead fluorescent tubes can be turned off.

Blinds are both patterned and create a contrast with the bright light coming through the darker blind. When the windows are open, the breeze may move the blinds, causing flicker, and creating a three pack of uncomfortable.  We suggest keeping blinds all the way closed or all the way open to reduce this trigger or use unpatterned drape or roll blind material instead.

4) Wear precision tinted filters

While you can make modifications to your own environment, you can’t change the world to suit your needs, so an important option is to get tested for visual stress and have your unique visual filters identified.  Everyone has a different optimal filter to improve visual perception, just as everyone has a different prescription to improve vision refraction.

Experience a reduction in symptoms

Making these changes can reduce commonly reported symptoms of Post-concussion syndrome or ABI such as:

  • Visual sensory problems: light/glare sensitivity, movement sensitivity
  • Visual Processing Problems: reading difficulties (word movement, intermittent blurring), and balance difficulties (world appears off balance)
  • Cognitive difficulties: fatigue, concentration, comprehension
  • Physical difficulties: headache, eye pain, nausea

These modifications should provide a more tolerable visual environment and reduce symptoms, leading to an increased ability to focus on other important aspects of recovery and rehabilitation. It is important to continue with other visual and physical therapies as these will help your brain get back to tolerating life and all the stresses that were managed before brain injury.

Hopefully, therapists and other healthcare practitioners have learned how their visual environment can be uncomfortable to those with acquired brain injuries and have made some of these modifications for their clients.

For more information on this subject, please contact Karen Monet, Founder at Opticalm.  [email protected], 613-294-6437