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One of the most reported triggers of Visual Stress is light. Lighting in public spaces, offices, classrooms, and other environments may be perceived as too bright by individuals with Visual Stress. The most reported light triggers are:

  • fluorescent light 

  • LED lighting; and 

  • computer screens. 


The Intuitive Colorimeter is an effective Visual Stress assessment tool that can help optometrists evaluate and identify the effect of light (and colour) on an individual’s visual and perceptual environment.  

office building sun light

Visual Stress triggers

Introduction to triggers

There are seven categories of triggers that can lead to Visual Stress symptoms: light, flicker, movement, colour, glare, pattern, and contrast. By identifying these triggers in the visual environment, it will be easier to remove or modify them. Reducing triggers should lead to a more comfortable environment and fewer Visual Stress symptoms.


When changes cannot be made, individuals should consider assistive tools and technologies to alter the visual environment. These include precision tinted lenses, coloured overlays, screen tinting software, E Ink (ePaper) electronics, LED lights, and coloured paper.  

7 Visual Stress triggers


Potentially, any stimulus that creates an on-off signal in the visual cortex can trigger Visual Stress. Flickering lights or images cause headaches in many people, especially those who suffer from migraines, and they can trigger seizures in people with photosensitive epilepsy.  


Flicker can come from light sources such as:

  • improperly installed lights;

  • strobe lighting;

  • electronic signage;

  • sparklers; and

  • sunlight on the surface of ocean waves.


When an image moves or changes quickly, the visual signal can trigger discomfort and Visual Stress. The visual system may become overwhelmed with the speed of the changing images and may not capture images adequately. Examples include: 

  • scenery moving past you while you are in a vehicle or on a bicycle; 

  • images or text scrolling up your phone or computer screen; 

  • the movement of fan blades; and 

  • busy environments (i.e., stores and public spaces).

If you have, or think you have, a sensitivity to motion or feel nauseous in busy environments, consider that it may be a sensitivity to the movement of light and images in your visual environment. 

Man Riding Bicycle on City Street


Light is different wavelengths that the human eye sees as independent colours. When an individual reports that they are triggered by light, it is usually a specific wavelength that triggers their discomfort, not the brightness of the light. 


Specific colours can create a sense of calm, while others can create discomfort or overwhelm. For example, you may feel happy in a room filled with shades of blue and purple but agitated in another that is a sunny yellow and orange.  


As mentioned in the “light” section above, the Intuitive Colorimeter is an effective tool that can help identify the effect of colour (and light) on an individual’s visual and perceptual environment. 

Prism and rainbow


Public spaces are filled with colours and lights, causing unavoidable glares and reflections. It can be observed on polished surfaces, glass doors, plastic, and more.  


At home or work, reflection and glare can sometimes be avoided, for example, by moving the angle of the light source or material. However, other sources of glare are not so easily, or cannot be, reduced. For example

  • vehicle lights at night;

  • a reflection of lights on wet surfaces;

  • shine on desks; and

  • reflections from walls, posters, and windows.


Geometric repetitive patterns, such as stripes, create an on-off signal similar to those caused by flashing lights explaining why these patterns can cause unpleasant somatic and perceptual side effects. 


Examples include: 

  • tiled flooring; 

  • horizontal and vertical blinds; 

  • an Excel spreadsheet; and 

  • patterned clothing and fabrics. 


A proportion of people who have photosensitive epilepsy also report that stationary gratings, stripes, or checkered patterns can trigger seizures, especially when there is a strong light/dark contrast in the pattern. Research has found that about 30% of photosensitive patients were also sensitive to patterns. 


High contrast can be overwhelming for some individuals. Text, usually black on white, also resembles a pattern of stripes with visually stressful characteristics. This explains why it can provoke Visual Stress symptoms of perceptual distortions and headaches. In addition, the visual grating created by moving the eyes across lines of print, especially where the pattern is glaring, can generate similar physiological effects to those produced by flicker and movement. 


Contrast can also be the differentiation, the variation between colours, shapes, and lines, that create an intense visual effect. Just like patterns found in texts, these can easily become overwhelming and cause perceptual distortions. 

Want to learn more about Visual Stress and its causes? Click here!

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