Eye Glasses

This was a very popular topic on Eskimo.com so, I have captured the essence here.   This discussion came from the web site nscra-list@eskimo.com (To subscribe to the list send an email message to: nsrca-list-request@eskimo.com and in the subject line of the message put: subscribe).

  In 1993 I had my eyes checked and got new prescription glasses (distance only) for flying. Every year since, I have had my eyes checked, got new ( usually stronger) prescriptions, had new glasses made and had my distance vision get WORSE (with the new glasses). I now have approximately four sets of new distance glasses, none of which work as well as my '93 prescription. I have gone to 4 different optometrists and 3 different opticians, attempting to get glasses that work. I have explained in detail to each what results I need. To date, no success. To be more specific, what the machine tells the optometrist I need, does not work in practice. And this has been the case with all optometrists, so all of their machines cannot be out of calibration.

I have even tried having the doctor make a set of adjustable trial glasses so I go outside and adjust them to where my vision seems best. Still no luck. It appears that all machines consistently call for too much correction in my left eye and too little in my right (discovered this after much experimentation on my own with the sets of lenses that didn't work).  Maybe some other flyer has experienced the same problem or there is an optometrist in the group that can suggest solutions. This is a frustrating situation and my vision has finally gotten bad enough that I cannot see the plane at certain angles, no matter how close in it is. Thanks for any help.

  Actually, I know how you feel about vision. I am far sighted and really don't need my reading glasses to see the airplane, but I have bifocals for the convenience of not always having to put them on and take them off. Like you, there have been a couple of occasions where the airplane just surprised me and in looking back, I think the problem was a shadow or reflection on the glass that distorted my vision. In my case this has only happened on turn-arounds where the distance could have been a factor as well. My solution is not to get more powerful glasses, but to get bigger glasses - something like the shotgunners and aviators use that should help widen the uninterrupted frame I look out of. My theory is that I'll see less frame and more airplane .. better around the periphery .. with lowered possibility of shadow or reflections. I'm not an eye doctor, however, so I may be on the wrong track. In any case, thanks for bringing up the subject. I'll be interested to see what other responses you get. Ted Westerman

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  I have encountered similar problems.  I don't think the establishment; really wants us to be able to call our own shots with glasses. I have been looking for +0.25 diopter lenses to place in front of my current glasses to try to optimize my prescription for 150 meters. So far, no luck. What I am really looking for is the set of lenses that the optometrist's used to use with the "try this"  method of selection. I have an astigmatism condition that makes too complicated to consider home brewing a pair of glasses. The lenses that are readily available in the drugstore reading glasses are on the order of +1.25 diopters. The best glasses I have had so far have come from the computerized diagnosis. I thought that the continuously variable lenses (Varilux) might solve the problem but I was unable to see a straight line with them! You sure get a lot of blank looks when you approach an optician and try to explain pattern flying and why you want to see like an eagle at 150 meters, even when you are willing to pay. The next step I have planned is to research the option of corrective eyelid surgery to provide more light. My eyelids are drooping  enough to restrict the incoming light. I don't think judging is impacted nearly as much as flying. We have to fly by the attitude of the airplane but we are supposed to be judging by the track. If it would help me see better I would be willing to fly with Darth Vader's helmet! John Ferrell

  I think that this is a very appropriate forum for this type discussion as it is an integral part of flying. I am fortunate that my optometrist is a fellow modeler who understands and has been able to meet my needs. Someone talked about bigger lenses. That is a very good idea. If you think about it we spend out time in part looking up at the top of the box and end up looking through the top part of the lens, unless you force yourself to look through the center and tilt your head. I suspect that we do something in the middle, but a bigger lens will certainly help. I know that the big lenses aren't fashionable today, but who cares. I told my Optometrist that I didn't care about what's on the boob tube, and that I wanted to maximize my vision for extreme distance. We ended up with a small + diopter, of how much I don't remember. Sure enough the boob tube isn't as clear, but I can see those airplanes. He also has a tinker toy glasses frame where he can build up my prescription for distance which we use as the acid test. I know you tried this and it didn't help you. ???? I have to admit that I don't have any serious vision problems, just a little astigmatism and lack of focusing ability that comes with age (60).  Ken Blackwell

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  I am not sure I have any answers for your situation, but I have a few related experiences and a solution that has helped me. I am nearsighted, (about -4 correction) have flown pattern for 3 years, and am a very rough Sportsman flyer. But, I have all of my glasses/prescriptions going back 10 years, I have tried them all for pattern. Over the 10 years, 4 optometrists, and 9 pairs of glasses, my prescription has varied by about 1/4 of a diopter (unit of measure for glasses)in all directions. Given that, I am amazed by the difference in my ability to see the plane out in the pattern! Some optometrists have said that your correction can vary from the morning to the afternoon ? Anyone know if it is true? 

Here is what I have found. A HUGE difference in visual acuity occurred when I purchased "high-index" lenses manufactured by Zeiss in Germany. The difference is really big and in two ways. 1) My visual sharpness is much higher, which I attribute to the thinness of the high index glass and to the skills of some German craftsman spending hours getting my lenses perfect (yea right!), 2) almost complete lack of curvature in the visual field. Most lenses (also depends on the amount of correction) have significant curvature of objects, and color separation of objects, as you get near the edges of the field of view. The Zeiss lenses have a very flat field of view, there seems to be very little color separation. I think it matters. What other types of lenses do I have and can compare the Zeiss lenses with? Four -- An unknown, but thick glass lens, an inexpensive standard polycarbonate lens, a "feather lite" (brand name) high index polycarbonate lens, and a Pentax high index polycarbonate lens. Now the interesting part, I have 4 pairs of the Zeiss lenses, one that is tinted amber (only color available). Despite supposedly having the same prescription, I see differently with each pair. And the oldest pair is the best! What to make of this, I'm not sure. I wonder about the quality control of the lens grinding process from the machines. I wonder about the geometry of the lens when it is mounted in a frame and you are wearing it. Seems like the distance from the lens in your eye to the lens in your glasses would make a difference, and would be critical. If so, what happens as the frames bend, or slide down your nose as the day wears on. I wish I knew the physiology behind this all this, but I do not.

If you want to try a Zeiss lens, they are hard to find and you need to call around. I am in the Northern Virginia area, and know of two suppliers. They are significantly more expensive, $450+ for the lenses alone. Also, for the highest index glass, which provides the thinnest lens, you need to sign a waiver. There is a law in the US that any lens must pass a test where a ball bearing is dropped from some height, like 3 (???) feet, and the lens must not break. The Zeiss lenses will. But, the thinness of the lens is what I think contributes to improved visual acuity. I usually have a pair of Zurich sunglasses over them anyway, so I do not feel unsafe.  (I wonder how much sharpness we lose via the multiple surfaces of sunglasses?) 

I guess to sum this all up, I have a bit of experience with different glasses, the Zeiss lens work very well, there are still differences between my lenses, and I don't have a clue why!  Another question, is it possible to have a prescription that would optimize vision at 150 meters? If so, would it be fair, within the rules, ethical, ..... Lou Olsen

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  It is not difficult to explain your situation at all. First you have to have someone that really intends to listen and do what you request. Second you have to refuse the lenses that are produced till he tests the lenses to see if they are as requested. You will have a ten percent chance of having them correct as I will explain in the following. Third your name has been around long enough that you are probably approaching the 40 shift syndrome. Take advantage of it. This means you are getting so you are mediocre in the middle and good at neither end . Now you have to coax; cajole; threaten to get those lenses set for infinity not the typical twenty feet for the normal "rest" distance. Let it be known in the beginning you are willing to pay for what works but not if they don't. By this state your trials and tribulations and lay it out as a challenge. If he feels threatened move on.

Now the asides. The tolerance allowed in grinding says that I am wearing plate glass. When they are ordered they are ordered with the threat they must come out as stated on the order. The same person in this hick town assists in the ordering as necessary as well as doing the testing. I know that for years the slight astigmatism has been passed over by over five examiners. Taking out the astigmatism (plate glass as far as allowed tolerances) made all the difference in the world. Some of the time I would see a leading image displaced by about the length of the engine. If I had a snap I could not tell which way it was going.

Remembering back as a kid I can remember my Father getting very angry with me for not being able to follow his hand signals but now I know it was the astigmatism. Now with this correction I normally fly gliders beyond the rest of the crowd by double or more. In addition I get my practice flights in after the rest have signed off at the field.   Rick Hallett

  I had the same problem; Finally my Doctor check the lens prescription - the lenses weren't what he prescribed. After he got through with the lens manufacturer, all my money back and the lenses made properly I don't have this problem. Let your Doctor check the lenses to make sure they are the prescription he prescribed. Good Luck Jim Rea

  You get what you pay for in most cases - I agree that Zeiss lenses are great in most cases as are Nikon lenses. Both company products are in the same price range, and they make terrific optical gear for camera's, eyeglasses, binoculars, telescopes etc.  In Germany, Zeiss will grind custom lenses for shooters etc. This service is not cheap, expect to pay upwards of $ 1200 per lens for a custom grind/fit and associated frame. If you are in your late forties, where your eyes usually undergoing significant changes in resolution, don't waste your money on these expensive lenses. Hanns Lim

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  It seems many of us have stories....which means the average age of the users of this list must be pretty mid-forty-ish... I am fortunate enough to have an Ophthalmologist for my eye doctor. This is a specialist who deals with diseases and disorders of the eye, and normally deals with pretty serious things. I started going to him to establish solid historical records of my eyes about 6 years ago. At that time, there were no abnormalities, normal vision, etc. Then mid-forties came...and the things that came with it. When I explained the correction that I needed, and why, he obliged. Fact is, if you need correction for airplanes, you need correction, period. The easy test was nighttime sign reading and headlight glare. Both were becoming challenging, and the correction he prescribed fixed both. THEN I TOOK THE PRESCRIPTION to someone to have Serengeti Drivers sunglasses made to match the prescription. The best investment I've made in Pattern since my transmitter tray. Many of you know about the advantages of the Drivers, coatings, UV protection, etc., and I had used them for years with no prescription. It was a time-consuming and involved task to get the correct prescriptions but IT WAS WORTH IT>>!!! *** FWIW - Take VERY good care of your eyes. Get them checked. ABSOLUTELY protect them from UV. ALWAYS. UV Damage IS accumulative over time.!!! If you need a prescription, use it ALL THE TIME....because your eye needs the correction to see properly, whether you're looking at airplanes or tv's.**** The mid-forties thing is presbyopia. Usually can be compensated for with cheapie readers, until the distance vision gets affected. Bob Pastorello

  An important message to add to this topic is that we all should buy the best lenses with the most protection for our eyes. This must include UV a,b... protection and protection from infra red spectrum which can cause eye disease eg. cataracts. I am not an ophthalmologist but am a physician practicing in Australia. I see a lot of preventable eye and skin disease related to solar damage. Common diseases to prevent include Cataracts, which are opacities in the lens and Pterygiums - fibrovascular growths on the sclera(white part of the eye) that can start to grow over the cornea (the transparent colored part of the eye). These Pterygiums can eventually cause problems with vision if they grow over the middle of the eye. When they are advanced they have to be removed. Chronic sun damage contributes to their development and it is important to get glasses that cover the sides of the eyes as the suns rays enter from the sides and top of the specs and damage the sclera. Small trendy sun glasses are not as protective.

Your best bet is to get the largest lens area possible to shade the eyes. No point getting lenses that enhance the image but don't protect the eye. Sun glasses will "cheat the eye" of its usual defense mechanisms against glare and the harmful spectrum. Normally when exposed to a bright light the pupils in the eye will constrict to protect the eye from the amount of light entering the eye. This is a reflex action called the light reflex and normally is so protective that even if light enters one eye the other pupil will constrict to protect the other eye. The reflex arc also supplies the muscles in the eye lids which will make the person squint to reduce the light entering the eye . Sun glasses reduce the intensity of the visible light entering the eye therefore consequently cause the pupil to dilate to allow more light to enter the eye. If lenses don't protect from non visible damaging spectrum even more of this will enter the eye now with a widely dilated pupil and with loss of the normal protective mechanisms resulting in more damage. The damage as Dick Hanson pointed in his post is accumulative. You would be better off not using the sun glasses if they did not protect your vision from damaging radiation.

Most reputable sun glass manufactures these days have a safety standard they must meet but there are a lot of cheaper lenses that still don't adopt this standard. Often the cheap but trendy looking glasses offer the least protection and are down right dangerous for your vision. Better off using these if you are a movie star or singer when you attend the MTV awards or OSCARS at night.

My advice would be to make sure you consult an reputable Optometrist or your Ophthalmologist before purchasing you lenses. If you take this sport seriously you need to protect your eyes. Of course there will always be some form of radiation entering the eyes or we wouldn't be able to see a thing. The best thing to do would be to check with the specialists and let them know of your requirements. I personally don't use polarizing lenses eg Polaroid's as they tend to vary the shades of light entering the eye which puts me off when I fly. This is because of the nature of the way polarizing lenses work and the different angles the light enters the lens as you look from one side of the sky to the other. Also remember to use sun screen with the most SPF(sun protection factor) you can obtain. Reapply frequently. Avoid being a candidate for Melanoma , Squamous cell and Basal cell Carcinomas.Wear a hat and cover up. Regards Hanns Lim