The use of anti-reflective coated lenses has grown by leaps and bounds in recent years. At the same time, more optical professionals have jumped on the edging bandwagon. These two trends combined mean that more in-office personnel are facing the challenges of processing these premium lenses. The coating has many advantages: It enhances the look of the eyewear and improves the wearer's view of the world while boosting the optical's profits. The higher prices commanded for this premium product mean that the practitioner is paying more for it, too. So the incentive to keep breakages to a minimum is high. Fortunately, some of the most common AR "uh-oh's" suffered by labs can be fixed quickly, simply, and cheaply. Here's how:

PROBLEM: AR coated lenses get scratched in the edger
SOLUTION: Manufacturers recommend using surface-saver dots to protect the surface of AR coated lenses from scratching. They're small-diameter dots slightly larger than leap pads and can be used on both sides of the lenses.

The dots are placed in the center of the lens because that's where it gets clamped in the edger and where it can get scratched easily. The dots also help to absorb some of the impact from the clamping. If you place a leap pad directly on the AR coating, when you go to remove it, it can "pull" at the coating. Also, using a "fragile" setting on the edger will help, if it's available.

-Michael Urban, Gerber Coburn

PROBLEM: Blocking tape doesn't protect AR coated lenses well
SOLUTION: The surfaces of some AR coatings are more hydrophobic than others. Standard blocking tape doesn't adhere well to the hydrophobic surfaces.

The problem that can be caused by slipping tape is that if the edger is heavy, the block can actually move slightly, and the lens will come out off axis. Instead, you can use the protective disks or lens pads that are made to adhere to coated lenses. Also, regular adhesive tape that is used for blocking will stick to the surface and help to prevent scratches.

-Bill Galindo, ODI/Topcon

PROBLEM: The AR coating gets scratched before it is edged
SOLUTION: The more expensive the lens is, the more precautions should be taken to protect it. I suggest using slip-stop edging tape, a thin plastic film. Put it on the back side of the lens before chucking in the machine. Also, put one between the leap pad and the lens when doing layout and blocking.

The question to ask when considering taking this extra step is whether it is worth the cost of using the disk. In addition to the time it takes to place the pad on the lens, you need to think about the cost of the lens and the price to replace it if it scratches.

-Matt Vulich, AIT

PROBLEM: The AR coating is ruined when the chuck is removed
SOLUTION: When deblocking an AR lens, put it into warm, soapy water. This way, the block comes off easily. Otherwise, if you pull the leap pad off without water, it can put stress cracks in the AR coating.

If tape is stuck to the lens well and you remove it dry, you actually can bend the lens, warp it, and crack the AR coating. But if you use the water to remove it, the block almost falls off by itself.

-Clark Smith, Santinelli International. EB

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