L&T: Lens Choices

May
2002

Kids Tough






Photo by Nedjeljko Matura


A new lens material raises questions about the possibility of expanded options for kids’ specs

By Brian P. Dunleavy

For Pia Hoenig, OD, April was a month of significant change. The Santa Rosa, Calif.-based independent pediatric optometrist and chief of the binocular vision clinic at the University of California, Berkeley fit her first child patient with Trivex lenses. Previously, all of her pediatric patients had been dispensed polycarbonate lenses, as is the general practice in the optical industry.

“I believe Trivex lenses are comparable in safety,” she says. The decision did not come easily. Dr. Hoenig, like any diligent eyecare professional, spent months researching Trivex, a new lens material introduced by PPG, the company that brought CR-39 to the industry more than 50 years ago. What she found was “a lens made of polycarbonate and a lens made of Trivex—with –2.00 D.S. and a 1mm center thickness—has identical impact resistance.

“I would feel comfortable prescribing either lens,” she continues. “Safety and cosmetic advantage motivates me to comfortably recommend polycabonate or Trivex and it would be difficult to argue that the clarity of Trivex wouldn’t be superior and therefore safer during the development of sight. Prior to Trivex, [though] my recommendations for all children had been polycarbonate.”

A NEW DEBATE
The introduction of Trivex has spawned new discussion over the lens options for children. Some parents will opt to have their children fitted with conventional plastic or high-index plastic aspheric lenses (for either optic or cosmetic reasons, respectively). But nearly all independent dispensers have, since the late 1980s, recommended poly as the material of choice, and they have made a practice of mentioning it first when dispensing eyewear to children. The Polycarbonate Lens Council (PLC) estimates that slightly more than half of the lenses sold to kids are made of poly.

Pushing poly to pediatric patients has been the recommended course of action ever since the Optical Laboratories Association (OLA) introduced its “Duty to Warn” program in 1987. The idea behind the program was to protect eyecare practitioners dispensing eyeglasses (particularly to children) from legal liability in the event of an accident involving a lens broken by impact.

The OLA program is not a regulated policy but a suggested operating procedure for dispensers. “Duty to Warn” states that doctors and dispensers have a legal and professional responsibility to make sure patients understand the risks involved in wearing eyeglasses and the relative safety of each lens material or frame style. Dispensers are urged to explain each lens material, along with the relative risks of each material. Those who have incorporated “Duty to Warn” into their practices and dispensaries recommend polycarbonate first. Parents who opt for a lens material other than polycarbonate are asked to sign a waiver.

TIME FOR TRIVEX
But “Duty to Warn” was drafted at a time when polycarbonate was the only “high impact-resistant material” on the market. Like poly, Trivex passes the U.S. Food and Drug Administration’s impact-resistance requirements for lenses when surfaced to a 1.0mm center thickness, according to the manufacturers working with the material, which, at press time, included Hoya and Younger. In some performance tests, they say, Trivex’s impact-resistance capabilities exceed those of poly.

It should be noted, however, there has been, to date, no independently researched and published study comparing the two materials in terms of impact resistance.
What makes Trivex attractive to some is its optics. Depending on the manufacturer and the lens design, Trivex’s Abbe Value ranges from 43 to 46, compared to 29 for poly. It also has a lower specific gravity (1.11 to 1.22) and is, unlike poly, tintable.

As a result of the growing buzz generated by the product’s introduction in 2001, the OLA plans to address its inclusion in “Duty to Warn” this summer. “Rather than changing ‘Duty to Warn’ to include Trivex, we’ll look at changing it to recommend ‘all high impact-resistant lens materials,’ ” explains Bob Dziuban, OLA executive director. Sources say the revised American National Standards Institute’s Z87 standard for safety eyewear will acknowledge both poly and Trivex as comparable strength materials once it’s issued.

Randy Dannewitz, current PLC president and vice president of sales and marketing for AOSola, says the PLC and its members would have no problem with this change. “If the OLA felt Trivex’s performance was sufficient to include as a recommendation to meet the ‘Duty to Warn’ criteria then the council would not create any opposition to that measure,” he notes. “The council’s objective is to promote the use of polycarbonate, not to prevent other materials from finding their place in the market.”

Dispensers who have used both materials certainly seem open to the idea. Says John D. Bonsett-Veal, OD, a Madison, Wis.-based independent practitioner, “I will only dispense polys at this time. But I am not against Trivex for kids. I just have not gotten started in that direction yet.”

lens list

ESSILOR EXPANDS NIKON PERFORMANCE PACKAGE Essilor has extended the range of its Nikon Performance Package to include Varilux Panamic in 1.67 high-index in an Rx range of +6.00D to –12.00D with up to 3.00D cylinder. According to the company, the new Crizal-coated lens uses an aspherized design allowing it to be extremely flat while maintaining excellent optics. Eyecare professionals can order the Nikon Performance package in Varilux Panamic 1.67 through authorized Essilor Laboratories of America distributors and through VisionWeb at www.visionweb.com.

INTERCAST LAUNCHES NXT Sunlens supplier Intercast has introduced a new family of polarized and photochromic lenses for the sun and sport markets called NXT. According to the company, NXT optical polymers provide impact resistance, visual performance, lighter weight and durability. They are compatible with all frame materials, have high resistance to chemicals and can be easily processed (i.e., drilled, notched, edged, assembled) without risk of stress cracking. NXT lenses are cast, ensuring low internal stress, high optical homogeneity and thermal and mechanical stability. The manufacturer says this makes NXT an ideal material for high-performance, stress-free polarized lenses.

NASSAU RELEASES NALCO PALS IN MINUS POWERS Nassau Vision Group has extended its NALCO progressive 70mm lens line to include minus powers. The sphere powers now range from plano to a +3.00D and –0.25D to –2.00D. Add powers remain at +1.00D to +3.00D.

VISION-EASE EXTENDS TEGRA Vision-Ease now offers its line of Tegra aspheric finished single-vision polycarbonate lenses in 65mm diameter in plus powers and 75mm diameter in plano and minus powers, with a sphere powers range from +3.00D to -6.00D, with cylinder of –0.25D to –2.00D. The finished single-vision lenses are available with Vivid factory-applied A-R.

J&J EXTENDS DEFINITY 2 ROLLOUT Johnson & Johnson’s Spectacle Lens Group has expanded the rollout of its first product, the Definity 2 progressive lens, which began in December 2001. Company executives say they are now able to produce a power range allowing dispensers to fit approximately two-thirds of applicable prescriptions. J&J has expanded distribution beyond its original Virginia test market, and is now distributing Definity 2 in Philadelphia, Boston, Milwaukee and Washington, D.C., as well as in Florida and Georgia.

 

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