The Sun: Man's Friend & Foe

[Picture of a pilot and plane] A pilots most precious commodity, their sight, will be the first thing to go if they don't take special precautions to protect themselves from the Sun. The Sun's glare can cause eye fatigue, astigmatism, and other eye problems. Aviators sunglasses are more than just a fashion statement; they can play an important part in safeguarding a pilot's vision.

There are several good reasons a pilot should wear sunglasses while flying. Glare is harmful to the eye; sunglasses, cut down glare and enable a pilot to make wiser decisions by protecting vision while in the air without being distracted. Eye fatigue is another good reason to wear sunglasses; pilots who do not wear sunglasses have a better chance of getting eye fatigue, and eventually, astigmatism. Exposure to heightened levels of harmful UV light reflected from the clouds is minimized by UV filtering sunglasses. The most convincing reason, however, is the adverse effect on night adaptation vision when unaltered high ambient light levels are endured during the day.

Older pilots should definitely wear sunglasses as older eyes require the rest that sunglasses provide. They should wear sunglasses that aren't very tinted and that allow the passage of more light to the retina but still cut down glare. This is because a 40 year old pilot's eyes require 40% more light than that of a 20 year old to see the same amount of contrast. A 60 year old pilot requires up to 100% more light than a 20 year old.

Ultraviolet Radiation
up to 290 nm	above 290 nm	above 315 nm
UVC Absorbed by ozone layer; little reaches earth	UVB The sunburn rays can cause snow blindness and cataracts.	UVA Passes through glass, causes sun related drug reaction.

Ultraviolet light with a wavelength of less than 315 nanometers is a known cause of cataract formation. Cataracts cloud the ocular lens making seeing difficult and can get so bad that it is nearly impossible to see. UV light with a wavelength between 300 and 400 nanometers causes fluorescence of the cornea and lens.

It is not necessary to wear special lenses, inside the aircraft, to protect a pilot from UVB light because the canopy and cockpit windows will block it, regular sunglasses will work. Open cockpit and ultralight fliers should always fly with either glass or polycarbonate sunglasses as they do not have windows to protect them from the adverse effects of UVB light.