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Vision’s Role in Safety Protection is More than Just Eye Glasses

Dr. Mark Kahrhoff

Eye protection isn’t just about personal protective equipment.

Most eye safety programs are built around the idea that good vision requires only image clarity and sound eye health, so the focus is on safety eyewear only. While these aspects of an eye safety program are essential, we have found workplace performance is impacted by vision for many other reasons all totally unrelated to eyeglasses.

Vision and the processing of visual information impact all aspects of performance including how people direct attention and maintain spatial awareness. An understanding of vision will improve any global safety program, even in areas considered unrelated to the eyes.

Situational Awareness 

The combination of “attention” and “spatial awareness of surroundings” are important because they comprise a form of “situational awareness,” which is vital for safety. We scan for information while moving through a changing world. Imagine walking down the street and turning your eyes and head to read signs while your body moves forward. Yet you do not fall. Despite that you are moving, the words do not smear or jump.

Part of what supports this ability are your eye movements. Let’s briefly discuss two types. The first, the scanning type, you must choose to make. The purpose is to place your retina to “see” the word, which means present it to your attention. Your vision shuts off for a fraction of a second during this movement, so words don’t smear. Because this eye movement supports information gathering, it must always involve a shift in your attention.

Another type of eye movement, this one happening without your conscious awareness, holds the image upright and stable so you can see it. Even when you bend down or tilt your head your perception of the world stays upright. This is a requirement handled by your visual system though, in part, it is actually the regulation of your unconscious eye movements.

These eye movements, and the information they gather, is paired with other visual cues and sent to regions of your brain involved in planning movement, maintaining balance, and giving a sense of limb position, all impacting spatial awareness.

  Vision Takes Place Unconsciously 

Much of this visual processing happens unconsciously because people cannot pay attention fast enough to keep up with the demands of functioning in a complicated world. Attention takes a lot out of us. We would collapse in exhaustion before the morning coffee break if we had to consciously attend to all the visual information used to organize our world. Too great a perceptual load leads to fatigue.

 Consider the simple task of walking from your car into the market. When did you stop to look at the curb as you passed from the parking lot into a store? Answer: Never. When did you last trip over the curb? Answer: Never. Now consider a person walking to the market while attending to their cellular phone. If you watch this person, you will see their gait is not the normal smooth gait of a person moving unencumbered. Steps are halting, oddly timed, abnormally short and perhaps abnormally “wide.”

If you watch them long enough, you will see that person trip over the curb and fall or get clipped by the automatic door. This person is at grave risk for a fall or “struck by” bodily injury because they have disordered the essential flexibility between their conscious and unconscious visual processes.

The brain is so overloaded with information requiring active mental processing, the unconscious visual processes cannot exert influence. The person on their phone is experiencing a constriction of their “perceptual” awareness, and this perceptual constriction is how people can become more prone to falls or other forms of injury.

High visual concentration can be dangerous 

Think in terms of the skilled trades which demand significant visual concentration. Tradespeople might easily have a perceptual field that is constricted just doing their job the best way they can.

Construction sites are often busy, crowded, and loud which increases the perceptual load on the worker. These sites are thought dangerous because of hazards like unimproved ground and the demands for inherently dangerous equipment. This happens, in part, because of the tendency of the visual-perceptual system to reduce peripheral awareness during periods of high central concentration.

A warehouse worker examining towering racks of parts, while searching for one specific item, is an example of a person who can become so “centrally focused” that they lose awareness of what is happening around them. Seeking the part is an example of a person who is performing a complex visual skill called “visual figure-ground” perception.

Space awareness can easily be compromised by figure-ground perception

Figure-ground perception is isolating upon the specific in a sea of distracting detail. This process requires the ability to make rapid shifts of attention (yes, rapid eye movements) without “looking past” the desired item.

Most have experienced the difficulty of this looking for a grocery item. With so many nearly identical boxes, you can’t find your item. You summon the attendant who steps forward and puts their hand on a box directly in front of you at eye level. You were looking right at it. The longer you looked, the less aware of your surroundings the more perceptually constricted you became. Both your central processing of attention and peripheral processing of space awareness were compromised.

It’s not by accident that you are more likely to see a fall, spill or something dropped in a supermarket. Minor collisions of carts happen constantly and resolve with a smile and a “pardon me.”

People don’t suddenly become uncoordinated in the market. Shopping is an everyday task involving intensive central focus, frequent shifts of attention, and complex motor planning guiding the cart up and down the circuitous aisles. These collisions are no less evidence of visual-perceptual complexity for their harmlessness.

Mental Fatigue  

Warehouse workers, after so many sequential eye movements, each requiring mental processing and shifts of attention, can experience mental fatigue and perceptual constriction. The use of lifts and ladders for accessing high shelves relatively restricts the “base of support” or the foundation on which a person stands and which supports them in maintaining balance and coordination. Perceptual constriction on a reduced base of support is a bad combination.

Selective attention and space awareness are complex processes rooted in the complexity of vision, specifically the visual underpinnings of shifting attention and unconscious planning of movement. The ability to maintain simultaneous central-peripheral awareness is a skill that is not shared equally by all people and a physiological process that can be either supported or confounded by our working demands and conditions.

These processes have little or nothing to do with eyeglasses or eye health. They are, nonetheless, visual processes. Vision is the foundational sense we all possess. 80% of all brain connections function in vision and the integration of visual inputs across many regions of the brain. Workers can easily be at risk for injury due to visual limitations despite having the best glasses and pristine eye health. 

Fecha de publicaciónmayo 12, 2020

BELT.ES no se hace responsable de las opiniones de los artículos reproducidos en nuestra Revista de Prensa, ni hace necesariamente suyas las opiniones y criterios expresados. La difusión de la información reproducida se realiza sin fines comerciales. 

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