Eye On Equipment
Perplexed Over Polarized?
By Susan P. Tarrant

QUALITY WORRIES
PROBLEM: Our practice wants to increase our sales of premium polarized sunglasses, but we are worried that we will not be able to process them properly.

SOLUTION: Thanks to technological developments, both on the part of the polarized lens manufacturers and the edging equipment manufacturers, polarized lenses are no longer difficult to process in-house.

There is sometimes a challenge when edging polarized lenses in the ability to see your markings for laying out a lens.

If you want to process polarized or tinted lenses, it is suggested to purchase a system that has a layout blocker that allows you to increase the illumination in order to see your lensometer marks. Other than that, polarized lenses are quite straightforward to edge.

--Matt Vulich, AIT Industries

SunClear polarized lenses from Polycore are one option in the polarized field

RINGING PROBLEMS
PROBLEM: How can I avoid the clear "ring" that appears after I bevel a polarized lens?

SOLUTION: Because today's polarized lenses have a laminated surface, the color does not go through the entire lens. When cutting into the lens to create the bevel, you are exposing the non-polarized material, which may appear as a "ring" along the edge.

One method of concealing this ring is to select a front bevel position rather than the traditional 1/3 to 2/3s position. The front bevel position allows the lens to mesh more closely with the front of the frame.

Of course, this process will only work for prescriptions using thinner lenses, and requires operator judgment on whether the Rx is too thick for front placement. But it works for many low and medium prescriptions.

--Tim Taylor, Briot WECO

DELAMINATION FEARS
PROBLEM: Is it true that polarized lenses can pose an edging challenge because they can delaminate?

SOLUTION: Delamination used to be a concern when it came to processing polarized lenses. Most of the problems were caused by the polarization material and the way the lenses were put together. Because the quality of the polarization process has drastically improved over the years, delamination is no longer a concern.

Improvements in edging equipment have also decreased the difficulty of edging polarized lenses. The new patternless edgers have computer-controlled grinding and chucking pressure, which also eliminates potential delamination.

There are some issues to be aware of when edging these special lenses. Make sure the manufacturer's 180-degree orientation marks are properly aligned. If the orientation isn't at exactly 180 degrees, the polarization will not work. Also, sizing is critical when working with polarized lenses. If the lens fits in the frame too tightly, the polarized lens will show stress points more so than other lenses, affecting the aesthetic and visual quality of the lens.

--Franco Aluigi, Santinelli International