Ask the Labs

by Karlen McLean, ABOC, NCLC

Pondering Polarized

Q Are polarized lenses good for golf? I�ve heard they aren�t because they make it hard to read the undulations in the fairways. But, I�ve also heard polarization is great for golfers. Please clarify.

APolarized lenses are excellent for golf. The glare eliminating properties and UV protection offered by high-quality polarized lenses should be taken advantage of during any outdoor activity, and on a golf course is no exception.

.For golf, we recommend different color polarized lenses depending on environmental conditions. A bright sunny day on the course calls for a brown lens, which is a great all-

purpose sunlens and will improve visual acuity on the links.

Early morning or late afternoon play is best served by a high-contrast amber lens that filters blue light and provides sharp definition in low light conditions.

A high-contrast lens will also serve golfers best on overcast or cloudy days.

Chris Bailey, marketing manager, KBCo The Polarized Lens Company, Centennial, Colo.

Crazy AR

Q I�ve heard that heat may crack/craze AR lenses when adjusting glasses in the beadpan or hot air warmer. How can I avoid this?

A Anti-reflective lenses should not be exposed to extreme temperatures, such as those found in most frame adjustment devices, which may reach temperatures over 150�F. Lens substrates such as CR 39, polycarbonate, and high-index are more susceptible to heat expansion than the materials found in AR surfaces.

As a result, when AR lenses are exposed to extreme heat, the substrate expands to a greater degree than the AR surface, resulting in

fissures across the lens surface.

Consider a balloon covered with an extremely thin layer of plaster. When air is added to the balloon, the balloon expands but the plaster does not, and the plaster cracks.

To avoid heat crazing AR lenses, remove lenses prior to adjusting frames in a heating device. Then re-insert lenses after adjusting the frame.

Pete Hanlin, ABOM, LDO, training and development manager, Essilor Lens Group

Acetone Alternatives

Q Can acetone be used on all spectacle lens materials and treatments, or are there cautions with particular materials that call for alternatives?

A We strictly use 100 percent pure acetone to clean lenses. This works on all types of lens materials. Pure grade acetone wipes clean and dries immediately, leaving no streaks, residue, or film. For removing factory markings such as PAL markings, we use a solution called All Off that works about 90 percent of the time.

Susie Lesher, vice president sales,

Brondstater Optical America, Inwood, W.Va.

Editor�s note: Pure acetone is widely available. Another option is Reagent-grade acetone, a high purity, contaminant-free solvent used in cleaning delicate surfaces.

If you have a question you�d like to have answered in Ask the Labs, send it to Karlen McLean. E-mail: mcleank@lwwvisioncare.com. Fax: 215-643-1705. An archive of past Ask the Labs columns can be found on the Eyecare Business Website at www.eyecarebusiness.com.