Free-form and Function

By Brian P. Dunleavy

Brian Paul, OD, considers himself a “picky” patient. That’s why the optometrist at Brantford Medical Centre in Ontario believes in the enhanced vision offered by free-form lenses.

“I’ve been wearing them for years,” he says. “Recently, I had some lenses made from another material and when I looked through them, I felt like I was in a fishbowl. Now that I’ve been wearing free-form lenses for a while, I won’t go back to anything else.”

So-called free-form or digital lenses – sometimes referred to as wavefront or high-definition lenses – have been generating a buzz in the optical industry for several years. The technology incorporates multiple measurements – which, depending on the lens design, include pantoscopic tilt, vertex distance and near viewing distance, along with the patient’s prescription and pupillary distance – into the surfacing process to generate a customized visual field that reduces peripheral distortion and aims to recreate the “natural vision” of the wearer’s eyes.

Historically, those with high plus or high minus prescriptions have benefitted most from what optician Rosemary Coleman, owner of Rosemary’s Optical Shop in Brockville,ON, describes as “the bigger visual field” of free-form lenses. However, the potential wearer population for this still relatively new technology continues to expand to include patients across the Rx spectrum, according to David Watson, an instructor at the BC College of Optics in Surrey.

“I actually have had mine for about a year now – and I am a -2.50D,” he says.

According to Dr. Paul, approximately 60 per cent of the eyeglass prescriptions he dispenses in his practice feature free-form lenses, including as many as half of the single-vision eyeglass wearers. “I see free-form as the future of single-vision lenses,” he says. “I know not everyone sells them and that a lot of people are concerned about the cost, but the edge-to-edge clarity really makes a difference.”

In addition to providing all eyeglass wearers with increased clarity, free-form lenses can offer unique function to single-vision wearers with specific needs. Recently, Coleman fit a long-time client and avid hunter with free-form single-vision distance lenses that he could wear while engaging in his weekend hobby.

“He was super-impressed with the free-form progressives that he wore day-to-day,” she recalls. “We gave him a free-form single-vision lens at +7.00D safety thickness that he could use for shooting. He came back and told us they were perfect. He could see well throughout the lens, even on the periphery.”

This enhanced performance has led lens manufacturers and optical laboratories across Canada to expand their free-form product offerings in clear and photochromic – in both progressives and single-vision; a leading manufacturer offers performance sunwear in the technology as well. However, not all free-form or digital designs are alike. Some feature an atoric front surface while others are fully optimized using position of wear and/or biometric data. Thus, eyecare professionals should try out free-form lens designs themselves before they start dispensing them. Drs. Paul and Coleman both emphasize this point, and Watson, who has studied the technology in order to pass along insights and dispensing suggestions to his students, says his own wearing experience gave him the most information.

And, as with any premium product, it is up to the eyecare professional to sell patients on what sets the product apart – both in terms of quality and price. Coleman says patients may not grasp all the aspects of the lens design; they just need to understand that the technology offers the closest thing to customized lenses available in spectacles.

“I always say to patients, ‘If you were buying tires, would you want tires from Michelin or tires from Wal-Mart?” notes Coleman. “It’s an easy choice. The quality of the product is there with free-form lenses. Now it’s about educating patients as to the benefits of the technology.”