HANDS ON - Ask the Labs
by Karlen McLean, ABOC, NCLC

RIMLESS DILEMMA

Q What is the highest Rx you'd recommend for a rimless frame in either poly or Trivex?

A Lens thickness in a drilled rimless is constrained by how long the screws are.

Most rimless hardware doesn't offer long enough screws for a high-minus lens. Replacing the screws that are supplied with other screws isn't a good idea because then you're tinkering with the right screw thickness for the eyewire and lens, and compromising the manufacturer's original design.

Do your research before ordering the job, and work closely with the lab by furnishing highly detailed information: the more information the better.

Don't customize the job too much. We'd recommend going no higher than a -8.00D sphere in any drilled rimless.

-- Danny Singer, president,
Ultra Lens Laboratories

HEATED ISSUE

Q How can I get the most out of my salt pan for easy frame adjustments?

A Try different sizes of glass beads and try table salt to determine which you prefer. Adding a touch of talc or baby powder periodically will stop the beads from burning in.

If you don't have a hot air warmer and are heating one of the newer, thinner zyls, cover the part of the frame you want to heat with a light cloth or tissue. Heat only that part of the frame and keep the frame moving.

-- Daryl Squicciarini, vice president, 1-800-OptiSource

TEMPERING DISTORTIONS

Q Patients sometimes tell me they see splotches or distortions in the rear windows of cars, on ATMs, and on other glass surfaces when wearing polarized lenses. Why?

A Certain glass surfaces such as ATMs or other LCD screens and windshields used in automobiles have been tempered for safety purposes.

Tempering increases the strength of glass. When looking through a polarized lens, you are in a sense looking through a filter which reveals internal stress created by the tempering process.

These stress marks are a by-product of standard glass tempering and have no effect on visual acuity.

-- Irland Tashima, President, Toledo Optical Laboratory

LOOKING DOWN REVISITED

In the September 2004 issue, an Ask the Lab question, "Looking Down," received additional helpful hints. So we're reprinting the question with additional solutions here.

Q We have a patient who has started using a walker. She's reluctant to give up the near vision of her bifocal, but has trouble looking down through the bifocal to negotiate steps. What can you suggest?

A In addition to PALs with a wide intermediate zone, a flattop 8x35 trifocal, a lower bifocal segment, and lowering and offsetting the bifocal temporally as suggested by Tim Steffey in the September issue, you could also use a ribbon seg or bar seg bifocal. They come in various sizes with 9mm and 14mm depths.

-- Terry Roberts, T. Roberts Optical, Corpus Christi, Texas

If you have a question you'd like to have answered in Ask the Labs, send it to Karlen McLean. Fax: 215-643-1705. E-mail: mcleank@boucher1.com.  An archive of past Ask the Labs columns can be found on the Eyecare Business Website at www.eyecarebusiness.com.