Bifocals and rounding out too high

[rusty sparrow]

I've been flying gliders and light aircraft including taildraggers twenty years on and off as money permits. I've never had any problems with landing until now, after a break during which I started wearing bifocals. Now I'm occasionally rounding out too high. Any comments and advice?

[pulse1]

I have used bifocals for some years. I too occasionally flare a bit on the high side but attribute this to not looking far enough ahead. It is possible that bifocals exacerbate this problem because, in my case, my eyes are constantly changing focus between the near and far distance. However, whenever I force myself to look well ahead I do not have a problem.

I play a lot of tennis and have the same problem so I play better when I don't wear them.

I notice this problem particularly when I am distracted on the approach by a feature such as a cliff or tree close to the end.

[DFC]

Do you have any problems driving past parked cars, judging distance to stop lines etc?

Can you confirm that you are using bi-focal and not varifocal lenses?

Did you wear single correction (to correct your distance vision) prior to getting the bifocals?

Has the distance correction prescription changed?

[rusty sparrow]

Do you have any problems driving past parked cars, judging distance to stop lines etc?

No

Can you confirm that you are using bi-focal and not varifocal lenses?

Bi-focals

Did you wear single correction (to correct your distance vision) prior to getting the bifocals?

Yes

Has the distance correction prescription changed?

No

[Whopity]

Now I'm occasionally rounding out too high.Where are you looking?

I have worn bifocals, trifocals and several different types of varifocal and they make no difference except when I am doing woodwork and I can't judge a straight line any more.

[Tony Mabelis]

Whopity,
I build large scale r/c aircraft, wearing trifocal glasses.
It scares the s!@# out of you viewing the parts from the side (appears that all I can build is Bananas), but the trick is to view the construction down its length, that way the lens has very little error.
My aircraft do fly straight!!
Tony

[DFC]

I think that if everything is as it was before you started having this problem i.e. you are still current then you need to get some practice in operating close to the ground while concentrating on reducing head movement and concentrating on moving your eyeball and making a concious effort to use the centre of the distance vision part during the landing phase.

One thing that can help - and you need to be a student for this i.e. have an instructor - is to first use your old single vision specs to fly an approach to about 6 inches and then fly along the runway for a short distance maintaining this height before going arround. If you are a bit rusty you might have to do this a few times. Then do the same a few times with the bi-focals while concentrating on not moving your head and keeping your previously established focal points in the middle of the distance vision area.

What you also have to do is to stop allowing the extra things that you can now see in the near vision part (even if they are a blurr) distracting you from your primary task. Keeping this picture constant - not moving your head- helps in this.

All you need is a small bit of practice.

Note - the reason why you need an instructor above is that you will not be wearing the appropriate specs during the initial practice and thus your medical is not valid.

[rusty sparrow]

Thanks for the helpful comments - at least I think I know what's going wrong!.

Instructor booked and I'm going to get some different bifocals before then - I only need a small vision area to read maps, set the altimeter etc - so will get a pair (not sure where yet - any suggestions?) with a smaller magnifying section so the main body of the lens is distance correction.

[Whirlybird]

As a helicopter pilot, I had problems with distance perception when landing in confined areas when I first started using bifocals. It sounds similar to what you're finding. It got sorted out when I got a pair with only a very small D-shaped areas for close-up, which I had to consciously decide to use to look at the map etc. I went to an optician who specialised in glasses for pilots; it was somewhere in the Liverpool area, and I can't remember where, and it's a bit far for you anyway. But if you explain the problem, any good optician should know what you mean and be able to help you sort it out. It's not unusual for different people to want different bifocals, depending on the type of work/leisure activities they do.

[rusty sparrow]

Thanks Whirly - useful to know that.

Which of the bifocal types shown at How to order Bifocal Lenses online (http://www.specsuperstore.com/articles/guide_to_buying_your_glasses/ordering_bifocals) did you get?

[Whirlybird]

Mine's not like any of those! It's a half-moon shape the other way up from the half-moons shown, right at the bottom of the lens, roughly in the position on 'Round 38'. And it's only about 22mm wide.

[24Carrot]

I went to a normal optician for my bifocals. One tip though:

I wanted to read charts more easily, which put me into the optician's standard 'reading glasses' box. However the eye-lap distance is further than the standard eye-book distance opticians use for prescribing. Even when I insisted on looking at charts on my lap, the large measuring lenses forced me to bend my head towards my lap.

It took me two attempts to get the prescription right.

Edited to add:
Having just done my Class 2 medical, I should mention that the AME tested at the opticians' standard reading distance.

[mykul10]

I have just had to accept that single vision (distance) lenses are no longer adequate, so have got both a pair of varifocals and (cheap) bi focals, both meet the requirements for my medical.

I got the bifocals first and tried them for 10 days - a weird experience - at first I didn't feel happy driving in them - didn't try flying. It was great to be able to look down and read things easily again, but I couldn't get used to them for general use.

Then came the varifocals - instantly much better - I drive and fly in them, with clip on sunglasses as required. They are not quite as good for reading as the bifocals but I can
read the half mill chart no probs. I still can't always read debriefing notes for students, but thats no the fault of the glasses. I will give the bifocals a go next time I fly and report back.

Maybe try varifocals rather than bifocals. My optician was able to give me an idea of a varifocal use before I ordered them with somes big frames and lenses that went over my existing glasses.

As an orchestral musician though teh bifocals are the only glasses that allow me to see the conductor, read the music and read the magazine on my lap! (oops!)

[rusty sparrow]

Went there this pm and they seemed clued up enough to understand what I wanted. I'll pick them up next week.

[Whirlybird]

Sounds good. I use Specsavers now and they're excellent.

[Captain Stravaigin]

What is the latest position on Varifocal Contact Lenses ? I know the FAA did not allow their usage a few years ago. Has that changed ? What about Europe ? Are they OK there ?

I use them for Diving, Riding, Driving and Hill walking and they are great. Pair of clear ordinary sun glasses for bright days and you are all set !

[BroomstickPilot]

Hi All,

I can't comment much on bi-focals as I have only ever had one pair and they were on a special prescription specifically for working at my computer and reading at my desk. All I can say is that I disliked them. I found the line between the two focal distances just too irritating. With bi-focals the reading section always has a 'sweet spot' that is just below the line. If you miss that then you don't see what you are reading quite as well.

In 2005, I returned to flying after a break of many years. By this time I was in my mid-sixties and regularly wearing varifocals. At that time it seemed to be received wisdom that one should never wear varifocals for flying under any circumstances. In fact, I used my varifocals without any difficulty whatever. The only caveat was that if I wanted to look at something that was situated well over to one side, I had to turn my head to look at it rather than just my eyes in order to avoid optical distortions.

Since then however, varifocal technology has moved on. There are now varifocal lenses where the whole upper half of the lens is thoroughly usable distance lens. You don't have to turn your head to avoid distortion anymore. I think these are, however, a more expensive ultra-thin lens and may be more expensive than the ordinary bog standard lens.

Eventually, I began to use two pairs of vari-focal spectacles for flying. Both had thin, metal frames (for wearing under my headset) and the latest varifocal lenses in a big 1980s lens style, which are anatomically better than the current small fashion size lens. One of these pairs had graduated tinting so that the upper part of the lens had a dark, sunglasses-density tint, which gradually reduced to nothing at instrument panel reading level. The other pair were clear plastic lenses. Together, these worked very well indeed.

Broomstick.

[flyboy2]

My optician agreed to supply me with 2 sets of bi-focals; one tinted at the top for normal daylight use whilst the other one is used indoors or at night.
Luckily my height-judgment hasn't been a problem.

Night-driving in traffic or on highway's under re-construction ( with many bright warning lights around) can be disconcerting due to reflections, thus requiring great care & even briefly removing them until the reflections are less.

Ordinary readers are fine if only reading, but for flying & driving my prescription bi-focal lenses are still best.

I had a pupil who just couldn't get the final landing roundout right when using his new bi-focals. The solution proved to be that during landing, his landing returned to perfect judgement if he temporarily removed them. It was possible that he probably only required readers then.

[Whitebeaches]

Checkout this link this should solve all of your problems.

Welcome to PixelOptics (http://www.pixeloptics.com/):)

[BroomstickPilot]

Hi flyboy2,

Thinking about this thread, I find I began to remember the day I first wore spectacles after my presbyopia (long sight) had first been diagnosed.

As I walked along the road wearing my brand-new varifocals for the first time, the pavement seemed to rise up as I approached, whizz past my ear, and then gradually subside to its original level behind me!

After wearing the specs for a day or so, however, this illusion subsided and I acquired a normal perception of distance when wearing specs that became permanent.

Clearly, had I been landing an aeroplane on that first day, I should have rounded out too high also.

Perhaps the answer, where someone in new specs is rounding out too high, is to send them home for a week or so to get used to the specs and then come back and have another try.

Broomstick.

[rotorfossil]

When it comes to judging round out height in fixed wing and hover height in helicopters, we make more use than we think of peripheral vision, so the sides of bifocals have to be for distant vision.
I have two sets of bifocals, one for fixed wing and one for helicopters where the height of the half moon close up reading parts are different to allow for the different heights and widths of the instrument panels. The only answer is to have a clear idea of where you need the close up parts to be so that you can flick your eyes down to the panel or charts without moving your head and then tell the optician what you need to do.

[chopd95]

To pick up on a few thoughts here;

1) Am a short@@@e, many years ago I struggled until the CFI suggested a cushion - totally uncool to walk out with one, but it worked !!
(With experience I was able to dispense with the embarrassing appendage)

2)Later in life I had the common ? problem that with distance vision specs I couldnt read the map/chart. Went to several opticians who didn't understand the problem ( one does feel a touch of a poseur when saying "I need them for flying?", until one great day in Southport I found The Man. He instantly said that he did specs for the guys at Woodvale and completely understood the issue. The solution was to get the biggest frames (old fashioned aviator shape) with side bars that slipped under a headset, and have the small inverted half moon bit at the lower part. All worked perfectly - until I inadvertantly dropped them and drove over them!