April 2005-
Sooner or later, it happens to most of us: You may be able to spot traffic before your passengers, but you find it getting harder and harder to read the fine print on an approach plate, or the tower frequencies on sectional charts. Squinting helps for awhile, but eventually most of us need reading glasses.
I was born nearsighted, and I’ve worn glasses since I was six years old to correct my distance vision; but never needed any correction for reading or other close work. At least, not until a couple of years ago.
Like so many others (including, I suspect, some of you) I found myself holding the newspaper further away, and squinting at the fine print. In the cockpit, it became difficult to read approach plates. I actually switched from NOS plates to Jeppesen plates after misreading a frequency on a NOS plate. Jepp uses bigger print, and that helped for awhile, but eventually I knew I was going to have to get bifocals.
That raised a question: Should I get traditional bifocals (the kind that Ben Franklin invented almost 200 years ago) or the newer “no-line” type? I thought about it, talked it over with my optometrist and decided to go with the older style for a couple of reasons.
First of all, they cost less—and that’s important, because I also wanted prescription sunglasses. Second, “no-line” bifocals actually have a shape that varies the magnification over the surface of the lens.
To maintain a given magnification, you have to turn your head, to keep the particular section of the lens that you’re using in line with your eye. I was concerned about whether or not that would interfere with my instrument scan. I’ve since talked to pilots who wear no-line bifocals and don’t have a problem, so evidently you can adapt to this.
My first bifocals, then, were no-lines, and I also came home with no-line bifocal sunglasses. Reading the newspaper at home, and approach plates in the airplane was much easier. I did find a few problems.
Since I wear glasses, I’ve used “Clip-and-Flips” instead of a traditional instrument hood. These look like flip-up sunglasses, but have most of the lens frosted over, leaving a clear area that looks similar in size and shape to where the bifocals were on my new glasses—and that’s the problem. The clip-and-flips blocked everything except the bifocals. That’s fine for reading the plates, but not for scanning the instrument panel.
I fiddled around and eventually found that I could fit the clip-and-flips to sit a bit higher on my frames and give me some non-bifocal lens for my instrument scan, but it’s not perfect, and one of these days I’ll probably give up and buy a regular hood.
The next problem came when I dropped my bifocal sunglasses and got a deep scratch across the right lens. It was so distracting that I really couldn’t use them anymore. As a stop-gap measure, I tried my old pair of single-vision sunglasses, and found they worked well enough to use—even for reading (with a bit of squinting).
In bright light, the pupil contracts, so you’re using a smaller part of the corneal lens, and evidently in my case that reduced the need for bifocal magnification. I could get by that way, and did for over a year. Then I found my eyes were getting tired at the end of the day, especially when I did a lot of reading, and I caught myself holding things further away and squinting at them—even with my bifocals. Time for a new prescription again.
This time, I opted for traditional bifocals on my regular glasses, but I decided not to bother with them on my sunglasses. Instead, I had the sunglasses made single-vision but with a gradient over the lens surface: They’re darkest at the top, and much lighter (almost clear) at the bottom of the lens.
I got the idea for this from a correspondent who wrote an email to me after I mentioned fumbling for sunglasses after bursting through clouds in one of my columns (whoever you are, thanks!) His idea was that by having the gradient on them, you can just look through a different part of the lens to reduce or increase the sun protection.
The one thing I gave up by doing this is polarization—I’ve always worn Polaroid sunglasses because they cut glare. Another reader wrote to point out that this can make traffic harder to spot. Often the first thing you see is glint from an aircraft, and Polaroid sunglasses cut the glint along with undesirable glare. Gradient coatings are non-polarizing. I compensated by asking the optician to make them as dark as possible across the top.
How did it all work out? Pretty well, but not perfectly. I find that I still need to switch glasses when climbing up into bright sunlight out of a fog bank. I also found that as my eyes continued to weaken, I really needed bifocals even on the sunglasses.
For awhile, I thought I’d have to throw my fancy new ones away—and then I found a solution. Aircraft Spruce and Specialty sells stick-on lenses made by Optx. They’re available in five magnifications from +1.25 to +2.5 diopters. The lenses are made of a flexible plastic.
To attach them, you clean your sunglasses, set them face down on a clean surface, and put a little water on the inside of each lens. Press an Optx lens against the water, and push to force the excess water out (it may take a couple of tries to get it positioned right).
Once the water dries you have bifocals—and the stick-ons cost just $19.95. This sounded too good to be true—but at such a low price, I figured it was worth a try (having custom bifocal sunglasses made costs me a couple of hundred bucks).
The one question was what strength to get. I visited a local pharmacy that sells reading glasses and tried looking through them. The lowest strength, +1.25, seemed to work okay, so that’s what I ordered. And I was positively amazed by the results—my homemade bifocal sunglasses work just as well as the custom glasses I use for reading.
I’m almost tempted to just buy single-vision glasses next time around and use the stick-ons to convert them, as I did with my sunglasses. I’ve got one more vision problem, which I haven’t quite solved yet: It’s getting increasingly difficult for me to find a distance that works on my computer screen—and as a writer and part-time grad student, I use computer screens a lot!
With traditional bifocals, I have two choices. I can sit well back from the computer and use the upper part of the bifocals. This is fine so long as I’m not trying to read fine print. Alternatively, I can scoot up close to the screen and use the lower part. This leads to neck pain. I find that I’m doing a lot of writing (including this column) on a notebook PC, which sits comfortably in my lap.
There is one computer program, though, that doesn’t run well on my laptop: Microsoft Flight Simulator. I use it to practice instrument procedures, and to “visualize” cross-country trips before flying them in a real airplane. That’s getting more and more difficult as my eyes weaken.
I’ve thought of three possible solutions. One would be to buy a really big monitor for my PC, so that I could sit several feet away and still read things on it. That would be nice if my budget was unlimited. Another would be switching to no-line bifocals, and I may do that the next time I need new glasses.
In the meantime, I’m considering having a special set of single-vision glasses made with a focal point at about three to four feet (the usual distance I use when working with the computer). Ain’t it he** getting old?
John D. Ruley is an instrument-rated private pilot, and a freelance writer specializing in science and technology. He’s also a volunteer pilot for LIGA International (www.ligainternational.org), and past president of the Modesto Airport Pilot’s Association. You can write to John at jruley@ainet.com.
Resources
Aircraft Spruce and Specialty
https://www.aircraftspruce.com/menus/ps/sunglasses.html
