Medical & HealthNews and debate about medical and health issues as they relate to aircrews and aviation. Any information gleaned from this forum MUST be backed up by consulting your state-registered health professional or AME.
I am a doctor, a pilot and a HEMS doctor. I have been aware for some tiime that very few optometrists understand the specific visual aid requirements for aviators. I have struggled to find someone to dispense glasses for the specific demands of flying (VMC, IMC, night, reading, intermediate range - instruments). I have encouraged an optician family member to think about this and he is opening a specialist optical outlet for aviators at Coventry Airport in January/February. He has recruited an optometrist who will conduct an enhanced examination on a flight deck which will fine-tune any optical prescription for night, IMC etc.
I've read all the posts about sunglasses and it's all been real helpful thanks. I'm looking at buying a pair of Serengeti Velocity Drivers Gradient glasses and am wanting to buy them online from a company in the US($112 as opposed to £165.00 in Sunglasses Hut), but has anyone bought any recently and know how much VAT and Duty there is to pay?
A quick question on the old subject of sunglasses again: After reading loads of peoples thoughts and recommendations I settled for a pair of Serengeti Velocity Titanium with the sienna gradient lens.
I loved the glasses but today I tried them out in direct sunlight for the first time. My vision was completely disrupted by blue haze, from a couple of spots when looking towards the sun to patches covering the whole lens when at an angle from the sun. I wouldn't use these for walking in direct sunlight, never mind in the cockpit. The problem seems to be the blue coating on the inside of the lens that I haven't noticed on the glasses in the shops (I bought these on line from the US (so cheap!)).
Has anyone else had these problems? It seems strange that so many people recommended the glasses and they have such a positive recommendation.
I realise this topic has been done to death and there is a wealth of threads with peoples opinion on what the best sunglasses are, however I'm struggling to understand the restrictions specifically relating to photochromic lenses and subsequently which sunglasses I should go for.
Under HP&L the JAA say that photochromic lenses are generally forbidden due to the time taken for them to adjust to changes in light. Indeed, a number of threads on here quote Bad Medicine on the matter of sunglasses, specifically the bit that says:
Quote:
Back to the original issue of photochromatic lenses. Photochromatic lenses have several disadvantages that render them unsuitable for use by pilots.
Firstly, their transition times are relatively slow. Photochromatic lenses take about five minutes to increase their density to the level of sunglasses, but more importantly, the bleaching time from maximum to minimum density can be as long as 30 minutes. Although there is a rapid lightening of the lens in the first five minutes, this may be too long when there is a sudden variation in light during a descent into or under cloud, or because of a rapid change in cloud cover.
Their second disadvantage is that, even when fully bleached, photochromic lenses still absorb slightly more light than untinted lenses. Since vision is critically dependent on ambient light levels, even this small decrease of light reaching the eye through photochromatic lenses is undesirable, especially at night or in low light levels. The inherent degradation of these lenses with time causes them to progressively become darker, as they become unable to reach the fully bleached state. This effectively prohibits their use in flying or controlling air traffic.
So theres me thinking it was a pretty much done and dusted matter that photochromic lenses were a no go for pilots. However in trying to work out what sunglasses to get, the ones from Serengeti have caught my eye. In fact, they've caught a lot of people's eyes from these forums and I reckon a good half of the posts on the matter swear by them. Add to that, most pilot supplies shops sell them and even found one web page saying they were part of the standard uniform for Delta pilots! (not sure if that last one is true or not).
But my dillemma comes from the fact that according to their website, all the Serengeti lenses are photochromic!
So..my question.. Has photochromic technology come far enough these days for it not to be a problem? Or is it that the Serengeti's only adjust from ~10%->25% in terms of light transmittance thus taking a relatively short time, and the issues surrounding photochromic lenses only really apply to lenses that go from completely clear to darkened? Alternatively, when the JAA says 'generally forbidden' it means its not a hard and fast rule and its up to you to make your mind up on what you feel comfortable with?
Any thoughts? Am I good to splash out on these, are am I going to end up with an expensive set of sunglasses I shouldn't be using half the time!
The problem with photochromic lenses for flying is that many aircraft and helicopters have glass windscreens and these don't permit UV radiation (just the same as in a car, so they're no use for driving either). Photochromic lenses depend on a chemical reaction to the silver halide or silver chloride with which they are coated. These particles are transparent to visible light. However, when UV light strikes these particles, they change shape and absorb a proportion of the visible light which causes them to darken, the darkness being proportional to the intensity of the UV radiation. It's because of this that some photochromic lenses are pre-tinted so they can be used for driving. Naturally, that makes them near useless if you have to do any night flying.
The Serengetti Velocity gradient lenses are definitely not photochromic. I bought a pair just last month to replace an identical pair I've had for years and consider the best pilot sunglasses I've ever had. I also use Oakley Whiskers because the side arms mould closely to the temples and don't reduce the noise-cancelling properties of my ENC headset.
Piggy,
I fly in a country near the equator, so I wear them nearly every day and I've never had a problem you describe with a blue haze.
Actually, what you said kinda answers my question but also kinda reinforces it because all Serengeti lenses are photochromic to some degree (just do a google search for Serengeti and photochromic, also mentions it on their website). When you say the Velocity gradient lenses I assume you mean the Velocity frames with Drivers Gradient lenses and according to the Serengeti web site they vary from 9% light transmittance to 24% light transmittance (for both the Drivers and Drivers Gradient), and the spiel at the bottom of the page says they adjust to the changing light.
However you say that by pretinting the photochromic lens they can be made suitable for driving/flying. Which I assume is the case with the Serengeti's in that they only go up to a maximum light transmittance of 24% (or less on other lenses). In which case they are not fully photochromic and are thus ok?
Am I making sense? Maybe I'm getting to techy with it and should just accept that they don't vary much so their ok to use...nuff said
(The Serengeti site also talks about the photochromic properties being impregnated during the firing process rather than using a silver alidade coating, so I wonder if this means they don't suffer from the problems you mention with the windscreens filtering UV)
In which case they are not fully photochromic and are thus ok?
That is absolutely correct. As far as I know, the JAA photocromic 'ban' is aimed at lenses that go from 'clear' to 'dark'.
Serengeti lenses only go from 'dark' to 'darker'.
Also, bear in mind the clear photocromic lenses will have some sort of focusing ability (whereas the majority of Serengeti lenses won't). Therefore, the user will need them to see and this might be restricted if they don't 'clear' quickly enough. If Serengetis are temporarily too dark, then the pilot can just remove them!
I fly with Serengeti Drivers Gradient lenses and basically use them in all conditions except at night. They are particularly good at improving contrast in flat light conditions.
HTH,
B73
PS Has anybody actually seen a reference to this JAA photocromic 'ban' outside of the HP&L textbooks? I can't remember seeing it in the ANO or AIP...
That is absolutely correct. As far as I know, the JAA photocromic 'ban' is aimed at lenses that go from 'clear' to 'dark'.
Serengeti lenses only go from 'dark' to 'darker'.
[...]
HTH,
B73
Helps a lot! Its what I suspected and what Phone Wind was getting at I think, but wasn't sure for certain that was the reasoning.
As for the what the JAA says on it...not much! Even the HP&L text book I have only says 'generally forbidden' and other articles (not from the JAA) I've read online say they are discouraged, but never seen anything to say they are completely banned or words to that effect.
Not wishing to stir the proverbial nest but I did come across an article on sunglasses for pilots that might be an interesting read relating to the Serengetis. They don't say they are bad but there are things that people should be aware of when using them and for that matter other sunglasses.
Hi all,
Have trawled through this thread attempting to work out which sunglasses would be best. I fly gliders and light aircraft, soon to go onto PPL, and hoping to go into aviation as a career (only 16). General consensus seems to be NOT Ray Bans. I like the look of the Aviators from Serengetti, but am yet to try them out. I have however tried some Oakleys with orange lense, which seem effective. So:
What would be best for general aviation. I'm looking for something to which will last me throught PPL and UAS for as long as possible, preferably in the classic aviator design. Do not need perscripted lenses of any kind.
Thanks
a somewhat confused Sam
Previously, I wrote about the new optical outlet for aviators at Coventry. I must declare an interest in this as I'm one of the directors. However, we put this together as no-one seems to be doing this for aviators. We have set up a facility to deal specifically with the visual requirements for pilots. We have built a flight deck on which we simulate all types of flying conditions as part of the eye examination (night, snow on the ground, IMC and bright VMC. This includes very bright conditions so that people can try out different types of sunglasses and see how each type measures up when confronted with a bright environment with different VMC conditions projected on a screen. Our customers can see how different lenses fare when trying to see little white gliders against a backdrop of clouds. The effect is really very good and helps people assess the efffectiveness of diffrent sunglasses in different glare conditions before they buy. We stock Serengeti, Oakley, Bolle and others. To clarify a few points - polarised lenses are discouraged, photochromic lenses are also discouraged. The military recommend neutral grey tints, helicopter pilots and many VFR pilots seem to prefer yellow tints as subjectively these provide better contrast definition. We're at Coventry Airport
Could someone recommend some reasonably inexpensive flying glasses? I'm a PPL student without much money to spend on such things. Would prefer something around no more than $75 US dollars.
Yes, it's a stupid question. read the thread and go to Google to find the difference, then make sure you don't buy photocromic or polarised sunglasses for flying
After reading the thread and browsing the High Street, I found the Oakley Crosshair is quite excellent:
huge unobstructed field of view
arms with kinks to lie flat against the head, so comfortable underneath a headset
usual Oakley optical quality and frame quality
I have a mild prescription - "spectacles advisable but not mandatory", it says on my Class 2 visual examination report. I got them with the plain grey (18% transmission) lens, and I'm very impressed. Good value at £240, too. I think they're about £140 without prescription lenses.
Can anyone tell me of a retail outlet for Serengeti Eyewear in the Manchester, UK region? After many years faithful service, I've lost my pair of Large Aviators & scouring the UK websites, they only seem to sell the Medium Aviators & I'm not sure they'll fit my big head unless I try them first!
Hi guys,
I wanted to see your opinion about which sunglasses you would all recommend for both flying and driving. I don't want to spend a million dollars on 2 pairs but I was looking at the VedaloHD sunglasses and they seem to work well for flying but Im not sure if they would have the same performance in the car (ie dark enough). Im willing to pay a good amount of money for them but I just wnat ones that would also not give me a headache (titanium would be ideal since my headset wouldn't push on them giving me a headache).
What do you all think?
I think there's still a lot of useful information in this thread. But if you want my advice, I find the Seregetti Veolcities to be great in this respect (with brown drivers' lenses). I use them for driving and flying (with LCD screens) - what I particularly like is the comfort when they are on for long periods. The arms are flat so they don't feel awkward under your headset and they are super light, despite the glass lenses.
I've tried many different sunglasses - Rayban, Bloc, Oakley etc and none come close in my opinion.
As someone in the business of Aviation Medicine, Hawk's post is an excellent summary of the current recommendations. The original work was done by an Australian Opthalmologist, John Colvin, when he worked at NASA. The results of the studies are published in the journals Aerospace Medicine and Aviation Space and Environmental Medicine. Do a medline search.
Summary of specifications: Large thin titanium frames for field of view
Polycarbonate lenses
Neutral density Gray Green tint
15% transmission of light
Hi,
I need to wear corrective glasses and am also looking for good sunglasses to wear when flying.
Question:
Can I get serengetis drivers gradient lenses with the right correction for my eyes or are they non-corrective lenses only?
In summer I'm going to London for a couple days. Is there an optician You can recommend, at Stansted airport or elsewhere in London, who stocks them and who has experience with pilots sunglasses?
Sam 
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