As pilots we are exposed to more of the sun's harmful rays than most everyone else, in large part because even when it is cloudy at the earth's surface we are operating above the clouds, high in the atmosphere and closer to the sun. Because of this it is important to understand how pilot's eyes interact with ultraviolet and blue light. Ultraviolet light waves carry a lot more energy than visible light waves, and therefore a pilot's eyes are at greater risk of damage from absorbing ultraviolet and blue light radiation. This is different from visible light which does not harm our eyes. Ultraviolet light, or UVA light, along with blue, or UVB light, can cause serious injury to eyes and have also been shown to be a cause of skin cancer. Prolonged exposure to these light rays can also cause permanent damage to your eyes, damage which can never be reversed; however, the effect of these rays on one's eyes various greatly from one person to the next. Blue light is visible light in the blue portion of the light spectrum and an example of blue light is the kind of glare that we see reflected from the surface of water or from snow. Eyes can not focus clearly in blue light, and routine exposure to UVB rays over long periods of time can age the retina and cause the onset of blindness in people over 60 years of age. Remember, all light is a form of energy, and when your eyes absorb light they cause a process within the eye that generates heat and can cause a chemical reaction within the eye itself. For example, the surface layers of the eye absorb UVB rays while the lens will absorb UVA rays and the retina absorbs visible light. UV radiation can cause drying of the eye or even temporary blindness and discomfort, and over a long period of time has been known to cause cataracts which in turn cause the eye's lens becomes cloudy. The preferred solution, of course, is to wear a very good pair of sunglasses which are capable of blocking out both UVA and UVB radiation. It is not the tint of the lens that causes a sunglass lens to block out these UVA and UVB rays, but rather the molecular construction of the lenses themselves. Polycarbonite lenses are very effective, when properly treated, of both blocking most, if not all, of the UVA and UVB radiation, and are durable and scratch resistant as well. There is another factor concerning sunglasses to be considered as well. For example, the past Sunday my wife was flying a Cessna 205 back from a trip we took up North, and was wearing her Randolph Aviator sunglasses. They were the 52mm (small) black aviators with bayonet temples and gray lenses. She remarked several times at how her eyes felt cooler, less stress and that she could see items more clearly through those sunglasses, better even than the ones she used to wear. Because the Randolph Engineering aviator sunglasses block the UVB, or blue light, so effectively she could see more clearly. In fact, as we were getting close to Lansing, MI she was able to spot the parachute of a skydiver that the rest of us struggled to locate when we looked for him. So not only were her eyes better protected and her vision improved, but she experienced no eye strain during the flight and her eyes felt cool and relaxed when we landed. You can find a great selection of these wonderful Randolph Engineering Aviator Sunglasses right here in our Pilot Shop. Until next time keep your wings straight and level Hersch! JetAviator7 What is the cause of most aviation accidents: Usually it is because someone does too much too soon, followed very quickly by too little too late. — Steve Wilson, NTSB investigator, Oshkosh, WI , August, 1996. ps: Don't forget to sign up for our newsletter "All Things Aviation" here!