Blinded by the Light: Don't Ignore the Effects of Glare on Human Visual

January 9, 2018

What Is Glare?


Glare is the uncomfortable sensation you experience from light that is too bright or too disorganized for your visual system to process effectively. If you have driven home into the setting sun, you have experienced one example of excessive brightness. Disorganized light is often even more problematic. It is exemplified by harsh reflections and scattered light.


Glare does reduce visual performance and workplace efficiency. Not all glare is equal, however.  Discomfort Glare causes that unpleasant feeling and certainly degrades visual performance, particularly if you fight it all day long. Disability Glare is experienced when the visual system has lost its ability to function normally. It tends to happen suddenly and is referred to as “dazzle.” 


I Work Inside. Glare Doesn’t Affect Me


Glare affects everyone, whether you work in an office setting or outdoors. For someone in an office setting, the most common sources of glare are overhead, particularly fluorescent, lights and computer screens. You can check for the effects of glare on your workstation by holding a folder above your work surface (between your desk and the ceiling). If your desk or monitor is easier to see with the overhead light obstructed, glare is affecting your vision. The same quick test can be run by obstructing light approaching you from the sides.


Glare of this type often result in a squint, which leads to eye strain, headache, and visual fatigue. It is, really, a form of repetitive motion injury and certainly degrades workplace efficiency. 


In a different work setting as in a factory with large bay doors or on a construction site, sudden dazzle from the sun can have far more severe consequences. Dazzle from reflected sun causes significant degradation of vision. Essentially every component of visual performance suffers including visual acuity, reaction time, reaction accuracy, object tracking and many other components of human performance involving vision.  For a construction worker, for example, sudden visual dazzle could result in a loss of footing on uneven surfaces sometimes at considerable height. 


I’m Seeing Rainbows


Everyone has experienced seeing “colors” after looking at a bright light. Here’s why: The visual system does not recover instantly from sudden exposure to bright lights. You are experiencing the eye “recharging” itself after a depletion of light processing cells. We call this “Light Stress Recovery Time.” Quite simply: You do not see well during this period of recovery. If you are on a construction site with cranes moving around, and you experience a dazzling light exposure, you are at risk. Period. 


What Can I Do?


It is possible to reduce glare. 


·        Think about the illumination in your work space. Work to create adequate but not excessive light. 


·        Think about the surfaces in your work space. Try to limit surfaces, particularly horizontal ones, that are highly reflective. Horizontal surfaces tend to scatter light. This is why fisherman appreciate polarized glasses so much. The water’s surface scatters light.


·        Wear polarized lenses but understand their limitations: They are not appropriate for pilots; they can make screens and displays “black out.” They tend to be very dark so are only appropriate for outdoor use in bright light conditions.


·        Think about diet. An increasing amount of good science is revealing that naturally brightly colored foods (carrots, kale, spinach, red peppers, etc.) improve visual performance by maximizing the concentration of pigment compounds in our eyes. More on this in another article soon. 


Whether your employees work in an office setting or outdoors, their visual performance is surely affected by lighting and glare conditions. Moreover, whether your employees’ work setting places them at risk for chronic eye fatigue or significant bodily injury, you need to be aware of the effects of glare on human visual performance.


Keep a watch for the next article, “I Got a Piece of Metal in My Eye: The Very Real and Long-Lasting Effects of the Most Common Eye Injury.”


Until then, thank you, as always, for a small part of your day. Please write or call if I can be of any service.


Dr. Mark Kahrhoff

Complete Safety, LLC.

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