Eye on Equipment
Plagued by pesky lab problems? Our experts help
By Susan P. Tarrant

Nothing is without challenge, including in-office lab work. Whether it's a recurring problem with a particular lens type, or a small imperfection in the finished product, it can be hard to trace the cause of the problem.

We asked our equipment experts about common problems they hear from their retail lab customers, and we asked them to share the solutions they offer. Here's what they said.

SOLUTION: We've had some retail labs call to say that when they're edging rimless lenses, the PDs are "off" when they check them after completion. We, of course, checked all the equipment first, and looked at the blocker, and looked to see if the edger was miscalibrated in some way. In each case, the equipment was fine. So we talked to operators and found out that the majority of edging jobs being done in those establishments were rimless lenses.

We watched the operators work and determined that they were removing one of the demo lenses from the eyewear in order to trace it. That was the problem.

When you trace a lens only (as opposed to inserting the entire eyewear into the tracer), the edger is set for the manual entry for the PD. This is where it's important that the true PD is entered; and removing one lens from rimless eyewear will affect a patient's PD relative to decentration.

A frame's PD is determined by many things, including the shape of the lens, the thickness of the lens, the depth of the groove, the tension of the nylor cord, and the flexibility of the frame. Once we remove one lens to trace it, one very big part of the PD equation has been removed. We have found that, nine times out of 10, the bridge will also spread out or tighten in (depending on the type of frame) once one lens is removed.

You must measure the frame PD prior to removing either lens in order to get the true PD measurements.

--Franco Aluigi
Product manager, Santinelli International

PROBLEM: High base curve lenses pose a challenge.

SOLUTION: Edging lenses with a high base curve is a challenge if you do not have a computer-controlled edging system that automatically produces a bevel that matches the curvature of the frame. The challenge is to avoid bevel location problems caused by "free- floating" bevel edgers that can't float laterally to accommodate the curvature of the lens.

To cut these jobs on older style edgers, start by cutting the lens large. Edge slowly to keep the bevel from running off the front at the nasal. You may need to finish the lens using a hand edger to get the best fit.

Alternatively, for fast, accurate results with these difficult lenses, upgrade to an edging system that measures five frame dimensions including the curvature, thickness, and frame bevel angle, and automatically communicates these parameters to the edger. This eliminates the need to bend and manipulate frames to match the lens curvature, which you want to avoid, especially with today's high-end frames.

--Andrew Bumerts
South central territory manager, Briot-Weco USA

Don't forget to leave the lenses in when processing rimless frames.  Shown: Cazal 153 for Ultra Palm

PROBLEM: Edging extremely thick lenses is tricky.

SOLUTION: If you're running a lot of thick lenses, you should make sure your edger has a wheel configuration which allows for wider wheels to accommodate these special instances. That would remove any challenge with edging thick lenses.

If you find you do have to update to a new edger in order to accommodate your problem, analyze the number of thick lens jobs you routinely perform in your lab versus the number of glass lenses you cut.

Ordering a machine to accommodate these special instances would eliminate the ability to cut glass material on our machines.

However, glass jobs make up only approximately five percent of the current market, and many retail labs send their glass jobs out to a wholesale lab, anyway.

--Matt Vulich
Vice president, sales, AIT Industries

PROBLEM: Uneven results with high-index lenses.

SOLUTION: Do you find that when you edge high-index lenses, there can be a slight inconsistency in the time it takes to process as well as the final size of the lens? You're not alone, as we have heard several of these complaints. The problem isn't with your equipment or your operators. It's a problem that I find generic to the industry.

Anyone who cuts a lot of high-index jobs finds it takes longer to run those jobs than regular CR 39 jobs, and it's true. They also find that sometimes there is a slight size variation. An in-office lab might do five high-index jobs in a row that come out perfectly sized, but the sixth one may be slightly small or slightly large, requiring a re-do. It's just the way the wheel interacts with the high-index lens.

At this point, I believe it's just an issue that we as an industry are dealing with. When polycarbonate first came out, it was a very challenging lens to cut, but we dealt with it and it's no longer the challenge it was. And that's what's happening with high-index lenses now, although they are much less of a challenge than when poly came out.

Understanding that high-index jobs will take slightly longer than others is the biggest hurdle. And know that a re-do here or there is likely. As long as you're expecting the issue, it may not be a problem for you. How often it comes up may mean the difference between accepting the situation and talking to equipment vendors and their customers to see who handles the problem the best.

--Tyrone Johns
Sales rep, Gerber Coburn