Wednesday, May 30, 2012

High Rx, High Wrap, Highly Awesome.

If you have a high power spectacle Rx, or you make eyewear, you are certainly familiar with the difficulties of fitting a thick lens into highly wrapped performance sunglasses. I remember years ago from my retail optical experience the days of mangling and twisting frames and forcing never-going-to-fit lenses into them. The results were always terrible, but in those opticals we neither knew the alternatives nor had access to them.

There are lots of amazing technologies out there to get the previously-impossible done, and done right. This is what happened when I decided to put a -5.00 into a high wrap sun frame. To tackle this job I tried out the well-reputed ICE-TECH lab out of Florida.

This is the frame I decided to put a -5.00 sun lens into
Anyone can make a highly curved lens that can match the curve of a wrapped sun frame. However, bad things happen when you do. First, the lenses become exponentially thicker at the edges. Second, many machines that cut lenses into the shape of the frame (edgers) can only make one type of bevel--flat--which will not securely hold the lens into the angled bevel of the frame. Third, dramatically deviating the curvature of the lens from the corrected curve theory standard (which for a high minus Rx is pretty close to flat) will introduce huge peripheral distortions, obliterating most of the visual benefits of the eyewear. Lame solutions for a professional trying to provide quality vision.

Ice-Tech's specialty is in using their own proprietary digital manufacturing process to generate unique custom curvature lenses that 1) dramatically thin edges on otherwise thick lenses, and 2) alter the optics of the lenses to compensate for the dramatic curvature and preserve excellent vision. And of course both Ice-Tech and I have advanced edgers that will also easily cut the angled bevels necessary to fit the lenses perfectly into any frame. I knew all this could be done, I just hadn't tried it. And the key factor in the entire equation was how well would the customer see out of the finished product?

You can see the unique uneven curve on the lens, designed to thin it out.

Even more dramatic looking through the lens. The center portion offers clear digital optics throughout what will be almost the entire finished lens area, and then the curves dramatically change to keep the lens thin. That's my edger I'm going to cut the lens on.
After edging. That is a -5.00 6 base lens! If you don't know what that means, trust me, it's thin.

Fit right into the frame perfectly, and looks practically plano (non-prescription).

Even more dramatic from the back. No protruding thickness at all.

Observing through the lens you can see the minor concentrated filed of distortion at the far edges of the lens. The digital technology allows us to basically redistribute all the distorted optics one gets from such a high curve and push it far out to the periphery of the lens where it has little impact and is minimally distracting.

Here the result of the custom thinning curve is most apparent, but that area of the lens is going to sit far to the side of the wearer's eyes, well out of the way of the functional areas of vision.
Final verdict, they absolutely looked awesome. Without looking close they were almost indistinguishable from non-prescription sunglasses. Final edge thickness was 4mm. Out of curiosity I calculated what a lens of the same material and curve would be without the custom digital aspherization: 9mm! That would have looked like crap and had far less visually usable area in the lens. I'm pretty impressed.

Best part of all, my customer's vision was excellent. I pointed out the edge customizations and explained the benefits of widened are of view, and as he looked around he said he could barely notice the edge distortions and they didn't bother him at all.

Ice-Tech are my new go-to guys for such craziness.

Ice-Tech on Facebook.


  1. Excellent post, High Base with High Rx comes up quite frequently. So many do not have the training to accomplish what you can do and just don't fulfill the customer request.
    Just as an FYI, some of the new equipment on the market it make it even easier,,here is a site if interested:

  2. Hi,
    Nice pair of Sunglasses. Do you remember what the prescription was? Was it a high negative? How much would custom lenses like that cost?

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