UV blocking contact lenses

[Justin]

I just thought of something strange...

I wear Acuvue 2 disposable contact lenses, pretty much all of the time, and these lenses are rated to block 100% of UV light. Even my eyeglasses are UV blocking, as most are these days. So, I'm wondering what spectra is actually blocked by "UV-blocking" contact lenses and what sort of optical density are we talking about? I realized that, while I have seen UV lasers in person (266/355/405nm), I might not have actually been seeing them correctly... Could the UV laser have been attenuated by my lenses, causing me to see less brightness than is actually there?

Does anybody have any experience with this phenomenon? Am I actually seeing the UV lasers like I should or am I missing out on something?

 

[FrothyChimp]

You are probably seeing them as you should. The Z87 standard for UV blocking is for diffuse exposure of UV A and B such as what you experience on a sunny day. Direct or reflected energy from a coherent UV source is much more intense and will overpower any UV blocking capability. This is why I freak everytime someone says their sunglasses block some wavelength or another. Yeah they block across the visible spectrum or some combination for the coolness factor but a direct shot to the eye and it's all over. If the lens is not to Z136 standards don't count on the protection.

 

[Switch]

My sunglasses appear to be blocking more of the blu-ray than they block the 532nm. But I'm only talking brightness here observed with the naked eye, no power meter or anything to tell of precise %. :-/

 

[Benm]

It depends on the make and model of sunglasses really. 405 nm is on the border, they arent supposed to block that well, but some might.. depends on the coatings. My sunglasses block ~400 nm by 80-90%, but they block the entire spectrum by about 50% too.

I doubt clear contact lenses will do a very good job in blocking 405nm. Lenses specifically made to block UV may show a drop off already at 405 nm. Ordinary contact lenses will not, as they have pretty good transmission all the way down to 300 nm or so.

 

[Justin]

Yeah, I know they won't block a direct exposure but I was wondering about my perception of the reflected light off a matte surface like our office wall. I suppose I'll have to pull one out of my eye to do a spectographic analysis... I noticed that my sunglasses completely block the visible portion of the UV blacklights used in clubs and it got me thinking about the contact lenses in my eyes blocking some of the diffuse light from our UV lasers. Thanks for your help, guys!

 

[suiraM]

If the lens is not to Z136 standards don't count on the protection.

Two questions, if you don't mind:


(a) Will they block a diffuse reflection, such as those from a matte surface or off angle from the main reflection?

(b) Are EN166-standard polycarbonate glasses' OD ratings in the UV range to be trusted for a direct reflection?


Not that I'm inclined to risk any reflections, but accidents eventually happen, I've been told (and am inclined to assume to be correct).