Although we can list multiple reasons to do and see outdoors, such as taking a walk and taking a deep breath to release stress, new research developed by the School of Optometry at the State University of New York (USA) offers new clues about which keeps our eyes healthy. And it has to do precisely with going outdoors.
Their study found that daylight improves visual brain cells, helping people better distinguish the finer details. The discovery could lead to improvements in mobile screens, further protecting humans from bad viewing habits, since, for example, spending too much time in front of the screen has already been linked to a phenomenon called “computer visual syndrome.” or “digital visual fatigue” (with symptoms like blurred vision, headache, double vision …).
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Read in different light conditions
The researchers conducted various tests on both cats and humans, measuring the response of visual neurons in response to dark or light squares. The participants wore EEG (electroencephalography) headphones that monitor brain waves.
The results revealed that visual contrast increased outdoors, indicating that reading in bright light stimulates the visual brain more effectively.
The amount of reflected light, or luminance , can change more than 10,000 times during the day. These fluctuations represent that the black and white parts of a traffic sign, to cite another clear example, can reflect 1,000 times more light at noon than at night.
“To our surprise, we found that the shape of the luminance response function changed with both range and polarity in black and white,” the authors explain.
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The importance of contrast
Vision research has operated for decades under the assumption that luminance contrast does not change with light intensity ; that is, a dark letter on a white page has the same contrast outdoors in brighter light than indoors in dimmer light. The study shows that this assumption is incorrect.
“The amount of light is continually changing in our visual world,” says Hamed Rahimi-Nasrabadi, leader of the work. “Our work shows that image brightness changes our sensitivity to light and dark contrast to efficiently extract information from natural scenes .” Exterior lighting improves contrast levels, making it easier to see lettering on pages.
In light of these results, we can already say that it is scientifically proven that visual contrast increases outdoors and therefore reading in bright light such as sunlight stimulates the brain more effectively. By increasing the amount of light, the contrast sensitivity changes for stimuli darker or lighter than their surroundings in opposite directions: it allows us to see the letters better and helps our eyesight.
“The new findings can also be used to improve current image processing algorithms and visual contrast metrics,” says the expert.
Referencia: The investigation was conducted by Dr. Hamed Rahimi-Nasrabadi and collaborators in the laboratories of Jose Manuel Alonso, MD, PhD, at the State University of New York College of Optometry.
