The One that Slipped Away

If you're edging or thinking about edging lenses with the latest super AR treatments, take these no-slip tips from several OLA-member lab executives

By Alex Yoho, ABOM

Things used to be pretty easy when it came to edging lenses, but that's changed over the years. While equipment is more user-friendly than ever, today's super AR lenses can present a challenge. The very factor that makes them such a boon for the user—their slippery surface—makes them a challenge to successfully edge.

Participants in a recent cyberspace OLA-member roundtable that gathered to share their thoughts and advice on working with AR lenses include: Chris Bowers, operations manager, Walman Optical, Minneapolis; John Granby, owner and CEO, Deschutes Optical with locations in Bend, Ore., and Boise, Idaho; Gerry Shaw, owner, Western Carolina Optical, Asheville, N.C.; and Jimmie C. Smith, owner, DJ's Optical Lab in Cedar Park, Texas.

Q. What is the main problem with super AR lenses?

Bowers: Edging the lens without slipping.

Granby: Slipping off axis in the edger causing delays, and breakage during in-house edging operations causing redos.

Smith: Most offices do not have lab people who know how to handle the new ARs. So they end up with a lot of breakage.

Shaw: We edge the lens prior to coating. But for uncut accounts, slipping is still a problem.

Q. How do you prevent slipping?

Bowers: Investing in newer machinery that can reduce feed rates and using special edging pads.

Granby: We use anti-slip stickers between the leap pad and the lens.

Shaw: We try to edge the lens prior to sending to AR.

Q. What steps can the average office take to avoid spoilage?

Granby: Use the best anti-slip pads, leap pads, and new leap blocks. Don't shop on price here!

Smith: Find the best slip stops AND train the lab staff.

Q. What should ECPs keep in mind when it comes AR lenses' impact resistance?

Bowers: The single legal requirement for spectacle lenses is that of impact resistance. The Food and Drug Administration has established impact resistance requirements for lenses through 21 CFR 801.410. ANSI Z80.1 further describes the Drop Ball test method.

Granby: Offices must understand that, as the final manufacturer, they accept responsibility for the safety of the lenses.

Smith: If the in-house lab does not take every precaution to keep the coating from cracking, the patient could end up with a piece of lens in their eye.

Q. What precautions should one take with today's lens materials?

Granby: Make sure every edger is calibrated correctly for the material. You don't want to re-edge lenses, which compromises the bond between the hydrophobic top layer and leap pad because you'll eventually get slippage.

Shaw: Some of the new lens protection pads have reduced slippage and spoilage.

Smith: To help protect them, double pad the lens on all high-end lenses.

Q. What can be done to prevent micro-fracturing or spider webbing with AR treated lenses?

Bowers: Minimize flexing.

Granby: Thin is not always the best. Some finished lenses are so thin that spider webbing occurs because the lens flexes during edging. Simply setting up and re-edging can be self defeating. Using lenses with a 1.5 center thickness are much better overall than lenses with 1.0 center thickness, and the cosmetic difference is minimal.

Smith: There is no true and hard way to be 100 percent sure you are going to keep this from happening. However, make sure you have a good safety bevel and be sure to rim the hole on drilled lens.

Q. What role does the edging machine itself play in safely producing AR lenses?

Bowers: To correctly produce these newer lenses, you should have the newer types of edger.

Granby: Sharp edger wheels produce a lens with no surface cracks, so the lenses are stronger and much more resistant to solvents a patient or dispenser will use to clean the lenses.

Proper leap pads can help control the slips and maintain the grips while edging super AR lenses. Image courtesy of Miki Sangyo

Shaw: Sometimes a slower feed rate, with reduced pressure, can help process AR lenses.

Smith: Make sure the pressure of the chuck is not too high.

Q. What precautions are important when mounting an AR lens?

Bowers: There are not any special precautions, but common sense can go a long way.

Granby: Get into the habit of touching only the edges. This prevents scratching and makes cleaning easier.

Smith: Check with a polariscope to make sure you do not have stress on them.

Q. Should AR lenses be final inspected differently than other lenses?

Bowers: There is no change in the quality standard for these lenses. Apply ANSI as usual.

Granby: Handling them with care and cleaning lensometer lens stops and hold-down clamps will help.

Shaw: We use a bright halogen lamp to do our first and final inspection of all lenses. This has been essential in identifying surface quality issues prior to AR coating.

Since AR treatments tend to bring out every defect, using halogen lamps has also helped in diagnosing polishing and fining issues.

Smith: Be sure to check for stress on the edge of the lenses.

Q. What recommendations can you make about AR warranties and how they affect the bottom line?

Granby: Hold the patient responsible for the care of their lenses. A warranty that replaces the base lens at no charge is "responsible," but the patient then is held liable for the AR coating and other add-ons. The office can charge for these, which helps the bottom line.

By not having a responsible and fair warranty, we risk devaluation of our product to the patient/customer. If we don't have the patient take responsibility for their eyeglasses and replace everything for free, there is no perceived value to the customer or patient. Then our product is seen as a commodity and that's what drives prices down.

Smith: AR lens warranties are great, but you still need to use your knowledge of the lenses. Be sure you don't set yourself up to fail by selling the lenses to patients who are not going to take care of them.

Shaw: Open-ended warranties are causing the industry problems. Lenses, especially high-index, are expensive and to offer open-ended warranties is a plague on business.

When we study the problem, it becomes apparent that it is costing us dearly on the wholesale side; and with most lens vendors not offering a warranty on lenses they do not provide with AR, it is especially costly.

The OLA is releasing its newest "OLA Tech Topic" on Edging Super Hydrophobic AR Coated Lenses. If you want the definitive technical reference on processing AR-treated lenses from start to finish, this work should have a place in your office.

Contact your OLA partner laboratory today and ask them for a copy. To find an OLA lab near you, visit www.ola-labs.org. EB