Prescription Sunglasses

[tvaner]

I have searched thoroughly through the existing posts trying to determine what sunglasses would be best suited for me for flying.:confused: It appears this has been a subject that has been lightly touched on in a number of threads but, there was not enough info that would help me to decide which is the best way to go to spend my hard earned.

 

Like many here I wear prescription lenses so the days of just buying a snazzy pair of sunnys’ has long gone. I don’t possess a pair of sunglasses and currently use multifocals for general use and readers for computing and reading. I would imagine that I am not alone in using this combination.

 

What I am interested in finding out is what combination do you find is the best option as far as effectiveness in cutting out glare when looking out the windscreen & readability in the cockpit for instruments, chart reading, prayer wheel etc.

 

There are a myriad of choices and combinations:

 

ie. Flips over existing set. Over covers for existing set. Transitionals v’s fixed colour. What colour? Distance. Multifocal. Bi-focal. Tri-Focal. Polaroid or not. etc. etc.

 

What combination works best for you? All suggestions and info greatly appreciated.

 

 

[mlpinaus]

I am basically myopic. Used to be able to focus up verrrrry close. With age that has

 

all gone west :black_eye:, so I now use bifocals, in glass, and they are photo chromic; they

 

go dark grey with UV. Works OK for now. I would expect that polariods would be

 

better tho

 

regards

 

Marcus

 

 

[Guest airsick]

This is a topic I encountered a while back and I found out a couple of interesting things. The first was to do with polarisation which I came across again yesterday while reading an accident report. This is an excerpt from the report which neatly sums up the main findings of my previous research.

 

Polarised sunglasses

 

Polarised sunglasses contain lenses that polarise the incoming light waves to the eye and reduce reflected glare from flat surfaces. Aviation literature identifies several limitations associated with the use of polarised lenses in aviation, including the potential for polaroid sunglasses to `mask the sparkle of light that reflects off shiny surfaces, such as another aircraft’s wings or windscreen' (V. B. Nakagawara, R. W. Montgomery, K. J. Wood, Aviation Accidents and Incidents Associated With the Use of Ophthalmic Devices by Civilian Pilots, Civil Aviation Medicine Institute, Federal Aviation Authority DOT/FAA/AM-01/14 July 2001). The CASA Designated Aviation Medical Examiner’s Handbook also states `Polarising sunglasses should not be used when flying. The polarising filter interacts with the cockpit transparency to produce a distorted and degraded visual field that poses a threat to air safety’.

 

The full report can be seen here - http://www.atsb.gov.au/publications/investigation_reports/2002/AAIR/aair200200548.aspx

 

My wife has also noticed that she cannot see the clock in her mums car when wearing her sunglasses. This is because the clock uses and LCD panel and is fitted with an anti glare filter that is polarised. Many glass cockpit instruments use similar devices and as such a polarised lens can also make it difficult if not impossible to see the panel.

 

Further to this the American Optometric Association - http://www.aoa.org/x5349.xml - has this to say on polarised lenses:

 

Polarized lenses eliminate reflected glare from a flat surface. However, looking through a laminated aircraft windscreen, while wearing polarized lenses, can result in a reduced retinal image. The Serengeti Strata lenses are polarized.

 

The other thing I came across was to do with transitioning lenses. The Serengeti range of sunglasses use photochromic lenses which is another name for transitional. They have had several recommendations against using their brand because of this.

 

All Serengeti lenses, except one, are photochromic and thus darken when exposed to ultraviolet light. Aircraft windscreens using polycarbonate materials may block ultraviolet light, reducing the protective quality of the lenses. Also, since a darkened photochromic lens requires time to lighten, aviators may experience visual performance loss when flying into clouds or darkened mountain ranges.

 

Also from The American Optometric Association - http://www.aoa.org/x5349.xml. The article also references:

 

Dully FE, Jr. Pilots' sunglasses: mystique or mandate? Flight Safety Foundation. Human Factors & Aviation Medicine. Jul./Aug. 1990; 37(4):1-4

 

I felt it was reputable enough to listen to what they were saying and subsequently chose not to buy/use lenses that are polarised or photochromic. As an aside I found it very difficult to find glasses that are not polarised, it took a lot of hunting.

 

 

[Guest Ginger]

Check out

 

http://www.aoa.org/x5351.xml

 

It is from the American Optometric Association and it is titled:

 

Ëye Exam and Aviation: Prescription for Success

 

 

[peter]

Went through this exercise a while back.

 

Polaroids certainly make the instruments including GPS difficult at times.

 

Blue is great for the ocean/sailing but I find it more difficult to pick out other aircraft.I ended up with brown, multifocal lenses and have been very happy with them.

 

If you are very myopic or have moderate or severe astigmatism you need to avoid the wrap around styles -- the peripheral distortion is quite pronounced.

 

 

[Guest Rocko]

Which optical devices are better for flying

 

You need to consider several factors.

 

If you're Presbyopic (ie. over 40, and needing distance and reading scripts separate), you have several choices. Since you effectively need to correct 2 powers at once (ie. Dist and near), you have the choice of Bifocals or Graduated/progressive/multifocal (same thing) lenses. 2 pair of specs just don't cut it.

 

Bifocals have the advantage of starting much higher up the lens, so if your panel is high, such as many GA type aircraft, it is more convenient than swinging your head right back and trying to see the panel. However, they are set at a fixed focal distance away from you (bi meaning 2 distances), so if parts of the panel are at varying distances from you, it can mean you have to lean forward to focus on them. However, Bifocals have the advantage of having a nice clear distortion-free distance area. There are many types to choose from...personally I recommend smaller round-segment bifocals, especially if you want to look out the side of a heli-view type door, since the reading is isolated to a specific area. Regardless of the type, the line can be annoying, and all bifocals are pretty useless for the computer (except for laptops)

 

Progressive lenses get gradually stronger from the top of the lens to the bottom. They do this without lines by warping the edges of the lenses, in particularly below the distance line of sight. This means you have a nice clear distance zone, but a small intermediate and reading zone. Because it scrolls through the powers as you look down, you often have to tilt back further to read than a bifocal. In most cases, the width of the reading area is significantly smaller than a bifocal, too. However, you do have the in between distances as well. All progressives require you to point your nose pretty much directly at the reading object, since the lenses are distorted to the sides. The distance between dist and near zones is called the corridor length. Different grads have different corridor lengths and widths, for different tasks. For example, in a small frame, you want a short corridor grad. However, this has higher distortions, because you're trying to change the powers faster, so often result in narrower reading areas, and increased distortions.

 

2 pairs...one distance, one reading? Forget it. Not for flying.

 

So, whats the best?

 

Totally depends what you want.

 

I'd always recommend either a small segment (round seg) bifocal, perhaps set a bit higher than normal, so you can see the panel without tilting back your head.

 

Alternatively, one of the newer design grads, which have a short corridor. This would include such lenses as Hoya Summit CD or Sola compact Ultra. These have higher distortions, but are much easier than tilting head right back to see at near

 

 

[Guest Rocko]

What about lens coatings?

 

All plastic lenses come with basic scratch resistant coating (unless you're a tight **** buying from a super budget crap store ;)

 

Unfortunately, hardcoat has a tendency to reflect light, so can be a pain when flying or driving with lots of lights around. During the day, it's fine. For night, you need multicoat/antireflective coatings

 

Multicoat coatings change the wavelength of the light on the surface so it no longer shows reflections on the lens surfaces. This cuts down on lens surface glare, but NOT glare from external sources. For night, nothing beats it. However, the trade off is a lens which shows the dirt MUCH more, and therefore requires much more frequent cleaning. Nor can you clean it on your clothing or hankie. It requires microfibre cloths at best, and often spec sprays into the bargain.

 

So, the choice? If you get hot and sweaty flying during the day, you probably want hardcoat for it's ease of cleaning. If you're going to also use them at night, it might be worth putting up with the cleaning of multicoat to get a much clearer lens.

 

 

[Guest Rocko]

What about Photochromic lenses?

 

There are 2 types....plastic and glass.

 

Glass, often called PGX, or photogrey extra, uses a lens where a light changing chemical is poured into the glass mix during manufacture. This mix reacts to light and UV, causing the lens to darken in sunlight. However, it has more of a tendency to darken indoors, and being glass, is much heavier than plastic. It also allows transmission of UV through the lens, so it is NOT a sunglass...you still get UV exposure with PGX. Additionally, it's rare we use glass nowadays, because of the safety implications. Shatter glass, and it produces razor sharp flints, which can slice the eye to pieces. Plastic doesn't

 

Transitions is a lens trade mark for photochromic plastic. It is a plastic lens, with a wafer of light changing material at the front, and a UV absorbing layer directly behind the light changing layer. This means the lens changes colour, but still absorbs UV, giving it a rating equivalent to a sunglass. Transitions can be either hard or multicoated, although multicoat does slightly effect it's darkening ability. It takes around 1 minute to go 70% dark, and 2-3 to go totally dark...in the order of 75-85% light absorbtion. However, this is very much affected by temperature...in winter, they go darker, in hot tems, they don't go as dark.

 

Serengeti sunglasses are not transitional, as such. They are actually tinted sunglass lenses, approx 50% dark, that go even darker with exposure to UV light.

 

True transitional lenses (Transitions being a brand name for a specific photochromic plastic) go from quite clear to quite dark. However, they require exposure to UV light to change colour. If you jump in a cockpit with a lexan screen or canopy, they'll change very little, because lexan absorbs UV. The same thing happens when you drive your car with Transitions. They don't change much. If you're flying or driving, and want dark lenses in an enclosed cockpit, you're better off with a dedicated sunglass lens instead.

 

 

[Guest Rocko]

Optical Sunglasses fall in a couple of categories.

 

A tinted lens is a plastic lens that has been heated in a dye bath of UV absorbing mixture, followed by a dye mixture. It's exactly like dying clothes. They can be tined to any colour you like, and any level of darkness. The level of tint has no impact on the UV, which is a separate mixture. You can have a clear lens with 100% UV absorbtion, and a tinted lens which still lets UV through (if the supplier has taken a shortcut when tinting). Tinted lenses are cheaper, can be done to pretty much any optical lens available, and will last a few years, although they have a tendency to fade over time with prolonged use. Thats why older tinted lenses often go pink....the green and blue components in the tint bleach out first, and leave the red last.

 

Polarised lenses are designed to block out reflected light, as well as direct light. When light rays hit a flat surface, all the rays line up, and become polarised. Polarised glasses cut this reflected light, where non-polarised lenses don't. THis means things like water are much clearer to look into, and road surfaces of bitumen and concrete aren't as glary. HOWEVER! While never experiencing this myself, I've heard a lot of pilots say it can be very difficult seeing a bitumen runway with polarised light, because it looks much less visible in texture. Also, polarised lenses tend to pick up distortion in material, so if you look through a lexan windscreen with stress areas, the areas go all crazy-coloured. Since LCD screens are themselves polarised, if your glasses are polarised at right angle to the direction the screen is, the LCD screen looks blank. Other effects, like the sky changing darkness when you tilt your head, are also seen.

 

So, whats the best colour?

 

Brown lenses are often popular for golfers, because they enhance objects on green backgrounds. Personally, I kinda like them on grass strips, but many other people don't. If you're colour blind, forget brown! It's actually illegal to drive with them (and, I assume, fly with them, if you are)

 

Green lenses (often referred to as G15), originally used in mass by Bausch and Lomb in their Raybans many years ago, aren't bad, but everything takes on a green tinge.

 

My personal preference is grey. It cuts all light colours evenly, so things just look darker without altering colour. We'd dispense probably 90% of our tinted lenses in Grey.

 

What do I wear? Nuploar 85% grey! I live with the disadvantages, because the glare reduction I feel is much better. However, everyone is different.

 

 

[Guest Rocko]

What materials to buy?

 

Plastic lenses are nearly 99% of the market now, due to safety and weight issues. Yes, they scratch more, but with a bit of care, they're quite durable. Basically, if they're dirty, wash them under cold water before wiping them, and avoid tissues or your clothes. Use a soft lens cloth, and keep it washed regularly. It comes in anything from standard density, to ultra thin and light, and has many, many options and advantages

 

Glass isn't worth the risk. One rock hitting the lens and having it shatter in your eye, and it's all over, Red Rover (err, sorry about that, Red ;)

 

Most of the big chain stores in Australia are owned by one company, who will remain nameless. They generally use only one brand of lenses, and have little access to anything else. Unfortunately for their staff, this gives them basically only one option of material to sell thats thinner and lighter than basic plastic....polycarb.

 

What's my impression of polycarb?

 

Polycarb is complete and total crap.

 

It scratches easy, it's more distorting, and it never edges well on the machines. Sure, you can whack a nail through it, but there are many other materials, like Phoenix and Trilogy, that are as impact resistant, yet harder and less easy to scratch. My advice is, if anyone offers to sell you a polycarb lens, tell them to stick it up their nose, because you will NOT be happy with it.

 

We don't do glass, and we don't do polycarb. Stick with plastic, and you'll be best served.

 

 

[Ben Longden]

Polaroid lenses play havoc with reading LCD screens, which are hard enough at the best of times to read in bright sunlight. Then the vision is distorted when looking through perspex - stress lines etc become visible.. No wonder they are not recommended!

 

Me, I have a pair of 'aviator' prescription multifocals, tinted to standard.

 

Vision in and out of the cockpit is crystal clear.

 

The problem then becomes perspex scratches when flying into sun...

 

Ben

 

(I had a pair of Rayban aviators, and got the lenses changed.. a hell of a lot cheaper than buying a new frame!)

 

 

[Guest Rocko]

Other options for sunglasses involve clipon sunnies over the top, or fitover sunglasses over your clear lenses. Neither of these is a particularly practical option when flying.

 

However, one option that is, are Convertible glasses.

 

They use a normal optical glass, with magnets built into the frames. You put your clear lenses (or transitions) in the main frame, and they then have a polarised grey clipon that magnetically sits over the top.

 

We sell the Convertible brand, and have done for 15 years. We've tried others, and either their clipons let them down or the quality is crap.

 

Convertibles are a bit heavier and a little dearer than buying a single frame, but they're a lot cheaper than 2 pairs!! We've found them to be very durable, and the clipons can generally be replaced (while the model is available) if you lose or damage them.

 

 

[Guest Rocko]

OK, so what do you do?

 

Damn good question. It depends on your needs, and what you're also doing with them....driving, sports, etc.

 

At the least, I'd recommend the following:

 

Separate pairs for clear and sunnies.

 

Transitions won't work properly flying.

 

Convertibles do work well, but you need to take the clipon with you.

 

Fitovers and clip on sunnies are cheap, but a PITA.

 

As for the choice between bifocals and grads...thats a personal one ;>

 

 

[Guest Rocko]

Hopefully, that answers a few questions ;)

 

Scott O'Kane

 

Optometrist - New Look Eyewear

 

Ipswich, Qld ;)

 

(at least the degree sometimes is useful for something apart from being a paperweight ;)

 

 

[Guest Rocko]

Oh, one thing I didn't really mention, is that both bifocals and graduated lenses have reading AT THE BOTTOM!. If you need to read something mounted high, say a roof compass or switches, then either "get a flip top lid", or you'll have to pull the glasses up to bring the reading higher.

 

Now, there are a few companies selling stick on bifocal segments, which can be applied to your existing glasses. Not the greatest quality, but might be convenient, especially if someone has good distance vision, and just needs reading, so they want something to stick on their non-prescription sunnies. Haven't had much to do with them myself, but some people like them...apparently...sort of ;>

 

Scotty

 

 

[Guest glider10]

zeis skylet or skypol

 

I have a set of multifocal , photochromic lenses which I have a clipon skylet lens

 

I find this an excellent lens for flying, the photochromic almost does not work inside a canopy. (gliding)

 

 

[Guest airsick]

However, one option that is, are Convertible glasses.They use a normal optical glass, with magnets built into the frames. You put your clear lenses (or transitions) in the main frame, and they then have a polarised grey clipon that magnetically sits over the top.

Not going to argue with an optometrist but...

 

Given that polaroid lenses are actively discouraged (not by me but more knowledgeable types) I don't see this as being a responsible option.

 

 

[wanabigaplane]

Half clip-ons.

 

I need my normal glasses to read maps and instruments, and sunnies here are not suitable because of darkness or polarization. For looking outside the cockpit, I need my polarized sunnies. The solution was simple. Purchase a pair of clip-on sunnies and cut them in half horizontally.

 

I tried getting graduated darkness glasses, but the attenuation was limited, and not polarized.

 

Jack. :):)

 

 

[Guest Rocko]

I think you'll find that the degree of effect from polarised lenses is relative. I have an Airmap 600c. The colour LCD worked fine with polarised lenses in the normal head orientation (ie. with the screen vertical, as it's supposed to be). Same should apply for Garmin and other equivalent units. However, if you had an AVMAP, you'd probably run into issues when turning the unit in one particular orientation. Also remember that most people wearing polarised lenses can still see their LCD watches, in the normal orientation. It's only when it's at right angles does the cross-polarisation issue take effect.

 

I also have a lexan screen under pretty high curve, so high stresses...also not disturbing to me using polarised lenses. Remember, if you're light aircraft has lexan polycarb windscreen, then it isn't laminated. So, the arguments against this mentioned by the AOA are irrelevant. It applies to laminated processes, where the distortion caused by the heat stresses where the multiple layers are glued together will be visible. Even then, it may not be a problem.

 

What I like about polarised lenses is the significant improvement in ambient glare on overcast or hazy days. Tinted lenses don't come close to cutting this, but just simply make it "darker". Personally, I also find it helps me judge the runway better, on grass strips.

 

As far as the "reduced glare from other aircraft" bit they mention, that is true, to a point. It ONLY reduces the polarising glare, in one plane of reference. Straight reflected glare will still be there. But, in a significant benefit, it will also reduce glare from other annoying sources, such as water, reflective roofs, cars, and every other reflectile ground object. This means improved comfort, and less distraction.

 

Some people don't like polarised lenses driving, for the same reasons. They're still one of the most popular diving lenses available. However, you really need to try them both in the situation before making judgement.

 

It's all relative.

 

 

[tvaner]

Thanks for all the detailed replies gents. I certainly ended up with a lot more info than I anticipated and it has helped change the direction I was originally heading and in turn probably saved me from getting something that would have been unsuitable.

 

The original plan, after some initial homework, was multifocal transitions/photo chromic. Looks now like multifocal with fixed colour, probably grey. Not polaroid.

 

 

[ahlocks]

Rocko, that was amazing!

 

Thankyou for taking the time to provide such an interesting and in depth series of posts.

 

Cheers,

 

Steven B

 

 

[Guest Rocko]

Grinz

 

Actually, I ended up cutting and pasting, then rewriting most of that for my work web page, so I did take a short cut there ;>

 

Glad it helped

 

 

[tvaner]

You sure have Rocko. Plus, I would imagine a number of others both now & into the future.

 

 

[Guest RLP]

good info Rocko, thanks. I'm at the oldmanopia stage with my eyes and have been trying different temporary fixes (for general use not aviation, as I don't actually fly), so your info is timely and much appreciated. Free consult with the optometrist - yahoo.

 

 

[Guest pelorus32]

Thanks for all the detailed replies gents. I certainly ended up with a lot more info than I anticipated and it has helped change the direction I was originally heading and in turn probably saved me from getting something that would have been unsuitable.The original plan, after some initial homework, was multifocal transitions/photo chromic. Looks now like multifocal with fixed colour, probably grey. Not polaroid.

G'day Tvaner,

 

I wish that this thread was around when I needed it. I did a bucket load of research about 18 months ago. I'm naturally long sighted and presbyopia has finally meant that I need both distance and close focus correction.

 

After all my research I sat in the cockpit and measured from my eye to each of the areas that was important (had some help with this). The primary instruments, the engine instruments on the other side of the panel and the small items on the centre console between the seats.

 

Then I took myself off to the optometrist. I asked her for tri-focals - main lens for distance correction, then a dual correction segment - the upper part for mid distance - the far side of the panel etc, and the lower part for charts, log, and the primary instruments.

 

My experience was that they were keen to help but had little knowledge and needed to be coached. The optical dispenser said it was two years since they had done a set of tri-focals or bi-focals. I got a set of frames and we marked the position of the segments on to a plain lens and I went and sat in the cockpit. It's important that you don't have to tilt your head for "normal" operations like S&L flight and reading the instruments. You also don't want the segments intruding too much.

 

Once we had the positioning right I had the lenses made (for two sets of glasses) and then had one set tinted with neutral grey. This is the colour that is recommended in a whole variety of studies as the least likely to cause problems or to mask objects. The tint is graduated so that at the bottom the close correction lenses have only a minor tint. The upper lens is more tinted. In retrospect the only thing I would change is to get a heavier grey tint - say 60% at the top.

 

I've been flying with these glasses for well over a year and they are superb. You don't know that the "lines" across the lens are there, if they are set up right. They are quick and efficient to use and you do not have any of the peripheral distortion that you get with the progressive additive lenses.

 

I have an untinted pair for everyday use and these ones only have the anti-reflective coating. This is a pain in the $^%^%. I would never have it again. It is very hard to keep any small amounts of oil off the lenses and very hard to clean them. If you yawn and screw up your face the small glands in your eyelids often spray a little oil onto the lens. It's impossible to get off effectively without washing the lenses. I hate them.

 

My tinted flying glasses do not have the anti-reflective coating and they are brilliant.

 

Best of luck.

 

Mike