Choosing the Right Sunglasses

In the off-screen, practical world of flying, however, cool-looking but inappropriate shades can definitely mean the wrong stuff from a safety standpoint. The price you pay for fashionable design could be a loss of visual acuity, distorted color and images, even blind spots—those places in your field of vision where other aircraft may be lurking, undetected.

That said, sunglasses do offer certain advantages. They can reduce eye fatigue and harmful glare, and can make it easier for your eyes to adapt to low-light conditions toward evening and night.

They can also block out potentially damaging ultraviolet light, the intensity of which increases 4 percent for every 1,000 feet of altitude. Too much of a certain wavelength of UV light over time may cause cataracts, or clouded lenses.

The goal, then, is to buy sunglasses tailored to your particular safety and health needs as an aviator. If they look good, too, so much the better!

For example, because older pilots have less pupil dilation than younger pilots do, and therefore need more sunlight to see well, they should wear shades that block out less light, according to Frank E. Dully Jr., MD, an aviation safety expert formerly at the University of Southern California in Los Angeles.

On the other hand, about one-fifth of the population reacts adversely to glare. So the pilots among them might consider sunglasses that keep out more, rather than less, light. (Lenses with a #1 rating block out 20 percent of incoming light, a #2 lens 70 percent, a #3 lens 85 percent and a #4 lens 95 percent.)

But all pilots should avoid polarized sunglasses, says Dr. William Monaco, an aviation optometrist in Wilmington, Delaware, because they eliminate the all-important glare or glint of light reflected from other maneuvering aircraft that catches your eye, alerting you to traffic nearby.

Other styles to avoid, according to experts, include:

Lenses that get darker when exposed to more light. They may not darken properly in the cockpit if adequate light can’t penetrate the window.
Cheap, department-store sunglasses made of soft plastic. They may not block out any of the harmful UV light.
Wrap-around glasses, which impede peripheral vision.
Yellow lenses, which make it difficult to distinguish between red and green—important colors on sectional charts and approach plates, for example, and at airports. However, yellow may be helpful in blocking out the blue light in smog, fog, haze and smoke.
Mirrored lenses. Aside from scratching easily, they can cause image distortions and blind spots.
Generally speaking, your best bet is #2 sunglasses with a soft green or gray tint that are lightweight and have adjustable nose pads so the frames can be moved close to your face for maximum eye protection.

When he isn’t flying, Paul Engstrom writes and edits from Sebastopol, Calif.

The information contained herein is meant for informational purposes only. Neither IFA, nor Paul Engstrom assume any responsibility or liability for events that occur due to actions you or others on your behalf take based on the information given in this article. You are proceeding at your own risk. It is strongly advised that you seek the opinion and advice of a qualified aviation medical examiner and appropriate medical physician for any medical needs you may have.