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As a pilot myself I have experienced eye strain and vision fatigue when piloting an aircraft but found a great solution which saved me many hours of discomfort.
But why do we experience eye strain and vision fatigue in the cockpit?
Is it worse today than in the past?
Vision Fatigue and Eye Strain
We have moved into the computer age and more and more computer screens are found at home, work and in the cockpit.
Our eye muscles change the shape of the lens in our eyes thereby adjusting the shape to focus for different working distances.
This is a particularly serious issue for pilots because we are required by the Federal Aviation Administration "to see and avoid" other aircraft traffic.
So we are constantly moving our focus from heads down looking at the computer screens to heads up and searching for other traffic.
When we look at a computer monitor we are asking the ciliary muscles of the eye to constantly contract a fixed amount to keep the screen in focus. This is just the same issue when our bicep muscles fatigue when we hold an object in a steady position.
I recall when learning to fly how I had to hold the yoke of the airplane steady in order to fly straight and level. This caused some real fatigue of those biceps on long cross country flights as I had to constantly work the trim tab.
What happens to our eye is that they get dried out from not blinking as often as they should. This means that the required rapid change from looking for other aircraft and watching our computer screens our eyes may not change focus as rapidly as necessary.
Most of the time we are flying clear of clouds and in bright sunlight, particularly at higher altitudes.
The ozone layer has been thining, the ultraviolet rays are stronger at higher altitudes and the bright light causes our eyes to dry out.
These extremely bright lighting conditions and large amounts of reflected light cause our pupils to constrict. This means our eye muscles are constantly adjusting the amount of light to reach our retina.
Different muscles, but the same fatigue sympoms.
So what do we do?
The key to reducing eye strain and muscle fatigue is to take frequent breaks from the screens and focus our eyes on distant objects.
Another option is an excellent pair of sunglasses to reduce glare and excessive light from reaching our eyes.
There are many types of sunglasses available, but no single type is ideal for every pilot. Needs change based upon age, light sensitivity of your eyes, ambient light conditions and flying conditions.
Sunglasses are important in the aviation environment to enhance contrast, reduce glare, decrease UV exposure, improved night vision adaptation and the avoidence of eye strain and fatigue.
Although style and appearance may be considered when choosing a pair of sunglasses, it is more important for pilots to focus on the lens features and frame style.
The most important issue for pilots is visual acuity.
Visual acuity varies with the amount of light available and the sensitivity of an individual pilots eyes. Older pilot's eyes may require more light than younger pilot's eyes.
Department of Defense Recommendations
The U.S. DoD has published Military Specifiations for sunglasses for pilots in a document called Mil-S-25948J_1984 and the Federal Aviation Administration (FAA) has published an Advisory Circular titled "Aviator Sunglasses for Pilots: Beyond the Image".
When it comes to sunglasses, however, there is a lot more to learn in order to make a great choice.
In my next post I will detail a lot of things to consider when purchasing a pair of sunglasses.
In the meantime checkout the very sunglasses that exceed the DoD Mil-S-25948J_1984 specifications: Randolph Engineering Aviator Sunglasses.
These are the very same sunglasses issued to U.S. military personnel.
In the meantime keep your wings straight and level Hersch!
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