As dark as possible

[Rich R]

Any standards on how dark lenses can be tinted as far as liability concerns. Sometimes at the patient's request we make them pretty dark, just wondering if I should make them aware or have them sign a waiver to cover myself.
Rich R

[Chris Ryser]

When tinting lenses very dark you also invite a larger amount of UV getting into the eye.

The darker the lens the more the pupil opens in full sunlight and double or triple the amount of UV reaches inside the eyes.

Therefore make sure you apply a GOOD UV treatment that lasts the life of the lens before tinting dark lenses or make sure the dye is UV absorbing or the lens has factory applied UV absorbtion.

One important thing is, do NOT use 1 minute UV solutions. These UV treatments will not work any more 3-4 weeks of wearing the glasses. Aproper treatment does need a minimum of 7 minutes of immersion in the hot solution.

[jofelk]

Why would a CR-39 lense show 95% UV protection, even though the lense has not been UV'd, after being tinted 80% grey or brown solid?

[Chris Ryser]

jofelk said:
Why would a CR-39 lense show 95% UV protection, even though the lense has not been UV'd, after being tinted 80% grey or brown solid?

Pure yellow absobs a lot UV.

Black is made by mixing yellow and blue = green
the you add red which bring it to G15 and further to black.

For a brown color you mix in more red, it will go from a sandy grey to a reddish brown.

If you measure on one of the UV meters which are geared to 380nm or 400 nm you will get the reading at those wavelengths. To get a perfect reading at all different wavelenght you would have to measure on a scanning spectrometer.

[lguess]

When we get such a request (and I think all of us do at one time or another) we show the customer a polarized gray 3 lens (Younger's glare box does a great job) and explain how we can give them a product that doesn't have to be so dark, will do a much better job than merely a dark lens, blocks UV, more comfortable overall, etc. etc. In the majority of cases, the customer goes for it, and everyone is happy- the customer has a superior product and we've just made a good sale.

Larry

[BobV]

I try to promote polarized lenses as often as possible. Reason being that most people confuse brightness from the sun and glare. Once a patient tries polarized, and notices that they don't need a darker than normal tint, they are happy. And they realize that glare has been their problem all along.

Bob V.

[PAkev]

Not only can a lens with very low light transmission be dangerous to health of the eye, It can significantly compromise the optical performance.

Those who remember the older manual SLR cameras know the apperature needed to be set smaller for distance and larger for near picture clarity. Similarly, the pupil apperature when dialated behind the lenses may see objects at near fine but not as clear for distance vision.

One of the beauties of polarized lenses is that the color density does not have to be that of conventional tinted lenses and therefore afford much more optical performance in doing so.

Since polarized lenses represent nearly all of our prescription sunwear sales and our use of cosmetic edge tinting, our tint unit only gets turned on about once every other week. By the way it is for sale and listed on the optiboard marketplace forum if anyone is interested.

Kevin

[aaron]

When I get those people that want it dark as night, there is usually some other stuff going on with there eyes. ie: severe dry eye, keratitis, new IOL's, etc....

Most people that are just sensative to light do very well with the polarized lense as the other posts have mentioned.

BUT,............for that one person who INSISTS that is be ridiculously dark, I just take a polarized lens (grey because it will always seem darker), and put it in the tint tank for a while. I haven't made it so dark that it would be a liability, and it always seems to be enough for that type of patient.

ad

[Bev Heishman]

We use alot of polarized lenses as the main reason people say their lenses aren't dark enough is due to tinting them dark to reduce the glare. Since switching to these we haven't had one complaint of not being dark enough or that the lenses fade in the sun or are unusually colored(like red).

For extreme light sensitive patients the variety of mirror coatings available today have been a fantastic help when combined with a polarized lens. We also AR back surface to eliminate reflections on conventional frames. Remember the darker the tint the more noticeable the back side surface reflections are.