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Killer Contrast Kate

Updated: Aug 19


Introduction


This note is all about contrast, reflection and glare from bad lighting that causes a range of painful and sometimes long-lasting conditions that go under the collective name of computer vision syndrome - estimated to affect around 40% of the population to a greater or lesser extent.

Symptoms include headaches, blurry watery or dry eyes, disturbed vision, sensitivity to light or photophobia. An estimated 25% of children experiencing these symptoms grow up believing that this is normal and are not diagnosed correctly for underlying conditions, leading to longer term issues. 




What is ‘contrast?

Our eyes were designed to adjust to light levels in natural scenes - the pupil, or muscles at the front of the eye, open and close to let in just enough light to stimulate the delicate tissue that lines the back of the eye, while keeping out the harmful rays that might bleach or burn it. 

But the glowing screen in the centre of a dark scene that is all too common creates a massive problem: the eye is constantly switching between those two conditions - causing the range of symptoms that go under the general heading of computer vision discussed above.



When the pupil is dilated to accommodate the dark condition, the delicate retina is exposed to an excess of the high energy blue wavelengths emitted by screens and cool white LED’s. This is worse for young eyes as some of the protective pigments are still forming - and continue to do so until late adolescence. 





Adding glare from a window, overhead lights or other sources compounds the issue, generating multiple focal planes and varying levels of contrast. 


What you can do about it

  1. Discuss the dangers and solutions with the people around you so that you can all look out for each other 

  2. Check for contrast, reflection and glare in critical zones of your home or work space - as a general rule, the screen should be no more than 50% brighter than the ambient light so that the eye can adjust to an overall level without strain

  3. Adjust screen settings – phones, screens and other displays

  4. Adjust ambient lighting – consider adding blinds and screens to defuse daylight, use low-level task lighting rather than overhead lights to minimise glare and reflections from overhead light sources

  5. Use timers and light-sensor switches to create a healthy balanced ecology of light that is healthy for eye and brain.

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