At first glance, processing children's eyewear doesn't seem so different from fabricating any other glasses, including the smaller eye sizes that are fashionable for adults. But look again, and you'll see that when it comes to small fry, there are special challenges. Eyecare Business brought the most pressing questions about this subject to the industry experts. Following are the solutions to these laboratory conundrums.

Q. Keeping It Thin
When I fit kids with plus prescriptions, the lenses always wind up looking much uglier than they do in adult frames. I know that plus lenses are thick in the center and thin on the edges, so why do these lenses always come out so bulky?

A.
The thinnest points of plus lenses are the edges, with the thickness increasing toward the center. The final edge thickness of a finished lens is always dependent upon the size of the blank that you begin with. Lenses are cut down around the optical center, so if you start out with a 76-mm blank and edge it down to, say, a 44-eye child's frame, you are trimming off the thinnest part of the lens, leaving the chunkiest portion protruding from the eyewire.

To avoid this, "don't use finished S.V. lenses," suggests Jay Little, vice president of worldwide sales at DAC Vision. "Instead, have the lenses surfaced so that they're specifically designed for the frame you're working with."

Q. Eliminating Re-Dos
I have noticed that when fabricating most eyewear, there are very few jobs that are kicked back because the final Rx doesn't fall within tolerance. Yet children's glasses seem to present more problems in this area. What can we do to cut down on the re-dos?

A.
Precise measurements are a must when making glasses for kids. "You can fudge a little with adults' eyewear, but accurate PDs are a must for children," says Bill Galindo, president of ODI/Topcon. "It's critical that you use a pupilometer and take monocular PDs," he adds. "You don't want kids to have to compensate for an Rx that's slightly off."

If it isn't possible to use a pupilometer because the child is too young or incapable of sitting still, for example, the next-best way to take the PD is by using a PD ruler to measure from canthus to canthus.

Q. Size Does Matter
The jobs that leave our office are as accurate as we can make them, but sometimes we get complaints from the doctors after they see their pediatric patients. When we re-check the glasses, they're within tolerance, but the doctors are picky about even the small things, such as how well the lens fits in the frame. Is there a happy medium?

A.
Children often wear glasses to correct developmental visual problems, so it's extremely important that the eyewear is as close to perfect as possible. "It's critical that lenses be sized accurately," declares John Stellano, senior technician at WECO International.

"If the lens isn't cut to exactly the right size, problems could occur. The lens could fall out or turn off the axis if it's too loose or break if it's too large," he continues. So the doctors who send patients back for re-dos are just looking out for their patients' well-being.

Q. Getting the Measurement Accurate
My lab manager and I have a running feud: she insists that I measure the frame dimensions every time I fit a patient -- especially a child. But I don't always have time to do that, so I just write down the measurements that are given in the catalog. Who's right?

A.
Your manager wins, according to Roger Reynolds, LOH Optical's consumables product manager. Lots of kids have more visual problems than simple myopia, hyperopia, or astigmatism. "When the lab grinds prescribed prism, for example, accurate frame measurements are extremely important," Reynolds says. "Frame measurements also affect the calculations for minimum blank size and thickness as well as for the actual prescription."

Since even a slight variation in size on a small child's frame can be significant, it's best to record the dimensions of each individual frame as you prepare to send it to the lab.

Q. Cutting Infant Frames
Our frame tracer can't handle the really tiny infant frames. What's the best way to make sure those lenses are cut properly?

A.
"Standard frame tracers may have difficulty if the eye size is smaller than 28 or the DBL is less than 10mm, although some of the newer scanners are capable of handling very small frame dimensions," points out Jay Lake, Briot's technical director. "If the frame is too small to be accommodated, the pattern must be utilized on a traditional edger. On a patternless edger, the demo lens or existing patient lens can be used, similar to the way they are employed when cutting a rimless frame."

Q. When Even Their Lenses Don't Cooperate
The edger that we use is a fairly recent model that is in good condition, but every time we cut a job for a kid's frame, it doesn't seem to want to cooperate. How do we make the machine fall into line and cut all the lenses equally well?

A.
"Many edgers aren't used to travelling to really small diameters, such as those found in children's frame sizes," says Michael Urban, product manager at Gerber Coburn. "So problems can occur because of dirty rollers and bearings. We suggest a thorough cleaning every two weeks, although everyone should follow the directions provided by their own equipment manufacturers. Don't pay attention just to the cutting chamber," he adds. "Continuous maintenance of the rollers and bearings is necessary for optimum performance."

Q. Special Jobs, Special Chucks
It's frustrating to try to cut lenses for some children's frames because the blocks run into the grinding wheel of the edger. How do I avoid having to take the lenses down the rest of the way by hand?

A.
According to Matt Vulich, vice president of sales at A.I.T. Industries, the use of special chucks will allow you to cut the entire lens on the edger. "Children's eye sizes often have narrower A and shallower B measurements, and regular chucks can hit the diamond wheel," he points out. "Try replacing them with special, smaller chucks that are designed for left and right lenses."

Q. Getting an Edge
It's not just the chuck, but the leap pad that also gets in the way when we edge little tykes' lenses. How do we get around that?

A.
"Getting around" the edge of the lens is indeed the problem with wee tots' jobs, acknowledges Stuart Watson, training director at National Optronics. "There's a limit to how shallow a B measurement an edger can accommodate," he says. "When edging tiny frames, use a half-eye block instead of a full-size one.

"Also, trim the leap pad so that it doesn't interfere with beveling or with probing on a patternless edger. If you don't, you could end up with a zig-zag in the bevel."

Q. Safety First
Is it necessary to add a safety bevel to lenses by hand? Our edger seems to do a pretty good job on its own, and kids' lenses are so small that they're difficult to rotate on the wheel.

A.
According to Santinelli International Regional Sales Manager Chuck Smith, the issue of safety must come into play when processing any job for a child.

"That's why polycarbonate is usually recommended for children," he says. "A good safety bevel is necessary so that no sharp edges that could injure the wearer are left on the lens." EB