UKC

I am going to the Alps for the first time in August (course with 4000m summit ascent). I need to order some prescription sunglasses (Cat.3) but looking at light transmission information there is a bewildering choice from web sites I have browsed: from 16% Light Transmission down to 9% depending on lens tint. Will any of these be adequate do you know, or is that just down to the sensitivity of the individual?

Thanks for any advice that can be offered.

David

In reply to DaveMinsh:

Cat 3 stops between 82 and 92% of visible light. Some would recommend Cat 4 stops 92/97% of visible light for glacier/snow travel and have a100% anti UV filter.

For RX sunglasses check out Julbo or Adidas Eyewear

http://www.julbo-eyewear.com/en/Outdoor/products/outdoor_%28snow_ice%29_7/b...

http://www.julbo-eyewear.com/en/Outdoor/products/outdoor_%28snow_ice%29_7/e...

http://www.adidas.com/Eyewear/content/?strcountry_adidascom=uk&strlangu...

In reply to DaveMinsh: I bought my prescription sunglasses from Optilabs. Emailed them and they sorted me out with a darker tint suitable for high altitude mountaineering. They offered a top rate service sending out several samples of frames to try with return postage paid. Then I just emailed them my prescription, paid and my glasses were delivered to my door.

I do think that how dark you want your glasses is down to your own choice. I have been on trips where people were wearing very dark goggles and still getting headaches from the sun while others were fine with there much lighter shades on. I find wearing a baseball cap under your helmey is a big help in keeping down the glare.

Enjoy your trip.

In reply to DaveMinsh:

I use the adidas climacool ones which are pretty good as you can change the lenses (low light lenses for cycling) and they have interchangable arms/strap which makes them good for skiing too.

Only downer is you can see the edges of the prescription inserts out of the corner of your vision, though you do stop noticing this pretty quickly.

In reply to DaveMinsh: I would recommend going to see an optician (a proper one) if you are unsure - it's something you don't want to get wrong.

In reply to DaveMinsh:

I got a pair of the Addidas ones from my normal optician. I was pleasently surprised that they cost less than my normal perscription glasses, coming in around £60 (that was a few years ago now). That probably just goes to show how over priced normal glasses are though!

Thanks for the feedback. I have tried frames on in a few shops and know what I want there. The course recommends Cat.3 or Cat.4 lenses.

Looking on the Rx site at lenses they listed several tints, all as Cat.3, but with varying light transmission properties (from 16% down to 9%). That was the aspect I found confusing.

eg:

VR28 Black Iridium - Medium to bright light. Filters blue light to increase contrast and improve depth perception in a wide variety of conditions. Features an Iridium® coating to diminish glare.
14% Light Transmission - Cat. 3

Black Iridium - Extremely bright light. Excellent all-purpose lens for sunny conditions. Offers truer color perception. Features an Iridium® coating to reduce glare.
10% Light Transmission - Cat. 3


David

In reply to DaveMinsh:

I think the transmission bit means how much light they allow through. Category 3 glasses allow between 8 and 18% of visible light through or stops 82 to 92% of visible light.

So the Black Iridium's offer more protection from visible light.

You can also get Photochromic lenses which can move from cat 2 or cat 3 to cat 4 depending on light intensity.

In reply to DaveMinsh:

Both of those lens tints you have mentioned are specific to oakley sunglasses.

Like mick said lens categories cover a range of light transmission i.e. 9% to 30% so cat. 3 lenses can have quite different light transmissions. Give the site a call sure they will be happy to offer advice, looks like you might be looking at the site i work for anyway so you might get through to me!

In reply to DaveMinsh:

I used a pair of Cat.3 Tog24 sunglasses (£24.99) with black lenses simply because they fitted so well.

Never had a hint of a problem in the July week I was there.

In reply to DaveMinsh:
Similar to the Adidas glasses, I have been using Rudy Project Ekynox glasses with perscription inserts. I have 2 interchangable lenses, the darker one (the darkest one they have, which is Cat. 3.) has been fine in very bright sunshine over 4000m.

Have a great time on your course!

Thanks for all the useful feedback.

I understand that the light transmission is how much light is let through; what I am still trying to fathom is what level of light transmission would be appropriate for the Alps with a Cat.3 lens.

I don't want to go too low and find that in duller conditions visibility is limited, likewise I do find I have a sensitivity to bright light. It seems to be somewhat subjective so I'll have to discuss with the suppliers.

Thanks again,

David