Progressive Lenses are the worst type of lens you can wear as a pilot.
Here are some of the problems:
1. You have to look directly at your target to see it clearly in focus. Good luck if you are older or have any neck arthritis, you will be swiveling your head to see clearly. Scanning your instruments frequently is difficult because your head has to be directed at the target, not just glancing your eyes up and down or to the sides.
2. When you look out of the corner of the lens, which you do when scanning the sky for bogies, the image will no longer be sharp. some brands are a bit better than others, but the higher your refraction, the worse it will be. You can easily lose 2 lines of an eye chart by looking out of the lateral edge of your lens. Two lines of a reading chart mean that an aircraft has to be half the distance from you before you will see it, compared to if your peripheral lens vision was the same as the center lens vision. Do you really want to give up that much of a safety margin?
3. When you look thru the intermediate section of the lens, the side distortion (to the left or right) gets much worse than the distance part of the lens. The intermediate and reader sections are quite narrow compared to the top distance portion. You won't see your instruments clearly on a scan unless you have only a very mild prescription in the lens.
4. When your eyes are forward (ex taxiing), and you want to catch the turn off numbers at an airport, these will be blurry because they are in the lateral portion of your lens (not straight ahead).
5. Because you will not be willing to do all the head tilting and swiveling necessary to keep your head pointed directly at what you wish to look at, you will wind up accepting poor vision in the periphery. That means you will miss seeing aircraft, because you can't scan the sky by directing your gaze up, down, left, or right. You actually have to point your head directly toward the area you are looking at, or else accept a reduction in visual acuity.
Opticians sell a lot of these lenses because they are about 3x the cost of regular lenses, and the profit margin is also about 3x. They usually ask only one question if you have reached an age where you need bifocals: "Would you like to have the invisible bifocal lenses (progressives)?" Of course, who would say no to that question? But, they will never tell you about all the compromises to your vision you have to accept in order to wear bifocals that are "invisible."
The best kind of glasses to wear as a pilot is single vision lenses. With these, when you glance to the far edge of the lens, everything remains in focus, just like the objects seen thru the center of the lens.
If you need bifocals or reading glasses, then the best type of bifocals for a pilot are called executive bifocals. These have a horizontal line just below the middle portion of the lens. Everything above that line is for distant vision. Everything below is adjusted for the focal distance to your instruments (approximately 24", rather than the 16" used for reading glasses). So, your outside vision will be perfect. Your instrument vision will be perfect. You will be able to glance left and right to see the sky or instruments without moving your head.
You will be able to go quickly between instruments and the sky without waiting for your eyes to accommodate to adjust to the difference in distance because that is already baked into the top and bottom prescriptions. Therefore, when glancing quickly at instruments, you will be able to regain your ability to see small aircraft without having to wait until your eyes "refocus."
What are progressive glasses good for?
1. Going out to dinner and impressing your younger boyfriend or girlfriend, you can read the menu without changing to bifocals or reading glasses.
2. Those who work in public relations positions, do podcasts professionally, or work in the public eye and have to have attractive glasses (newscasters, for example, that can't read their copy without bifocals, don't want to appear to be using bifocals).
For a pilot to give up the amount of visual acuity that exists in almost all progressive lenses is absolutely crazy and dangerous. Would you fly without your glasses if your vision was 20/40, and with glasses it was 20? If the answer is certainly not. Then why fly with progressives, where the periferal vision probably drops down to about 20/40, while the central vision is 20/20?
The FAA should ban progressive lenses in commercial pilots as a safety hazard!
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