Processing jobs in-house has a number of inherent advantages, including quicker turn-around times and better patient service. The flip side is that by taking the responsibility for finishing lenses, the operation also incurs the risk of ruining a job if a mistake is made.

It's a heartbreaker to have to eat an expensive lens because of human error. The additional time and money that must be spent when re-ordering the lens defeat the purpose of in-office processing.

As Nancy Safran, Briot's director of marketing, explains it, everybody has a percentage of mistakes that they make. Most are operator error. "Today, opticals are processing more high-cost lenses, so people are more concerned about re-dos," she points out. "When lenses cost 50 cents each, it wasn't a big deal to eat the job. Now that we're processing lenses that cost 20 dollars each, it's more of a problem."

To help you cut down errors that can send premium lenses directly to the waste bin, we've asked Safran and other industry experts for their advice on eliminating expensive re-dos.

Problem: Scanning and cleanliness

Solution: "Cleanliness is the key to processing jobs more accurately," Safran says. "Sometimes lenses don't fit because of a bad scan, which can occur if the scanner head gets dirty," she says.

"Also, if there is dirt on the scanner probe, the lens size will be incorrect. So follow the manufacturer's suggestions, and keep your equipment clean."

Problem: Sizing problems

Solution: "When you're cutting a lens down," explains Matt Vulich of AIT Industries, "always go a little bigger than size. Even with a patternless edger, there is still one variable that doesn't allow exact sizing. The diamond wheel doesn't always cut for the perfect angle and depth of bevel, which is one cause of sizing problems."

When tracing a frame, most tracers cannot accommodate for the angle of the frame bevel, Vulich adds. "If you're cutting a premium lens, you're probably putting it into a premium frame, which may be a little thinner and shallower than other frames."

So what can you do about it? "The key to making the lens fit correctly is to cut a little large, then do a re-touch. Going over size a bit will save you a lot of re-dos," he says.

Problem: Optical center off

Solution: Clark Smith, northeast regional manager at Santinelli International, stresses that being careful at all stages of the job is crucial to processing lenses correctly. "If the optical center is off, that's a big problem, so double-check your lensometer findings before you block the lens to make sure that the OC is correct. Also, take your time. Be careful as you're running the job the first time, and you won't have to re-do it," he points out.

Problem: Calibration problems

Solution: According to Joe Meaney, director of technical services at LOH Optical Machinery, you can avoid problems by calibrating and monitoring equipment functioning regularly.

"Implement quality-control checks along processing lines," he advises. Also, keep equipment in top processing condition by following the manufacturer-suggested maintenance programs. These steps will eliminate at least 90 percent of waste," he says.

Problem: Incorrect blocking

Solution: Blocking the lens correctly will also help to ensure that the job is cut properly, according to Randy Smith, a service technician with National Optronics. "Finishing blocks wear out from being de-blocked, and this wear can cause an axis shift of between one and two degrees," he says. To make sure that the block you're mounting on an expensive lens will not cause axis inaccuracies, check to make sure that it's a snug fit in the chuck. If you can rotate it a little, that means your problem is that the block is wearing out.

"Also, keep a couple of new blocks on hand that are marked 'do not use,'" Smith recommends. "Periodically compare the blocks that are in service to the new ones to determine whether any wear is occurring."

What about the importance of pads? "Don't skimp on leap pads. Use high-quality pads that aren't too sticky," he advises. "If you have to fight to pull the pad off the lens, you can risk ruining the coating."

Problem: Accidental scratching

Solution: Michael Urban of Gerber-Coburn recommends that lab personnel use surface-saver tape on both sides of the lens to guard against accidental scratching. "Apply the tape before chucking the lens in the edger to protect against any denting of the surface that can occur from the edger or the chuck," he says. "The tape will also protect the lens from any chucking pressure."

Problem: Scratched AR-coated lenses

Solution: "On high-value lenses, such as with anti-reflective coats, put a lens protecting pad on the front surface to minimize scratching during edging," advises Bill Galindo, president of ODI/Topcon.

As for what pads to use, "there are clear plastic disks that are available just for this purpose," he adds. "It's better to use these pads rather than leap pads, because these are made to adhere to hydrophobic coatings, such as AR."

Problem: Poor bevels and polishing

Solution: "Many times, customers want to have multiple options for processing on their edgers," explains Linda Little of WECO International, "so they choose an all-material wheel set. These wheels will do the job, but not as well as wheels designed for the specific lens material."

Better polish and superior bevels will result from a set of wheels designed for plastic, polycarbonate, and high-index, rather than from a set of all-material wheels, Little stresses. "The customer should decide what the optimal performance of the edger would be and have the edger customized for the best lens end-results," she adds.

Problem: Incorrect measurements

Solution: Tracy Morrison, marketing manager at Optical Works Corp., advises that lab techs "check and double-check the measurements before laying out a progressive or other super-expensive lens. Make sure that the fitting optician was correct on the frame measurements, and didn't just take the numbers off the records."

Despite such concerns, Morrison stresses that it is crucial to good finishing that the operator not live in fear of making an error. "Don't be scared of the high-dollar jobs," she says. "Just make sure that you have the necessary knowledge before you attempt to cut the lens."

What if, despite preventative steps taken, an error occurs? She says, "If you do have a re-do, it's important to understand why the mistake happened so that you don't repeat the error." EB

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