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Polymer’s new multifocal RGP targets emerging presbyopes
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ROCHESTER, N.Y. — Polymer Technology has introduced a new multifocal rigid gas-permeable (RGP) contact lens, the Boston MultiVision, which the company said will give practitioners a new option for fitting the 4 million people who become presbyopic each year.
The new lens incorporates posterior aspheric optics with the Boston ES material, a fluoro-silicon-acrylate material with a Dk of 31, to deliver a nominal add of +1.50. The 9.6-mm lens is available in powers from –20 D to +20 D, in 0.12-D increments. The base curves range from 7.3 mm to 8.3 mm in 0.1-mm steps. The lens design utilizes multiple aspheric curves combined with a unique fitting curve.
The back surface and the edge of the lens are pre-established, and the local lab simply finishes the front, said Tim McMahon, OD, from Chicago. Dr. McMahon was a clinical investigator in studies of the MultiVision funded by Polymer.
Alan Sartain, vice president of marketing and sales for Polymer Technology, said the idea was to develop a lens that was easy to fit and comfortable to wear.
Easy-to-fit formula
For Dr. McMahon, that formula has worked. "It’s extremely easy to fit and doesn't require specialized fitting knowledge, which is different from multifocals of any vintage," he said. "Another advantage is that the lens appears to be extremely comfortable when compared to others."
"It’s the easiest bifocal lens I know of to fit," said Stephen Byrnes, OD, a private practitioner in Londonderry, N.H., and assistant professor of optometry at the New England College of Optometry.
Dr. Byrnes believes the fit "is comfortable because you have a gradual taper into a fairly wide peripheral curve." He added that the lens’ high edge lift — 120 microns — allows it to move easily on the cornea.
Dr. McMahon said the lens’ comfort may be "an unintentional advantage of the peripheral lens design." He has fit about 40 patients in the 18 months he has worked with the lens, with good success. In pre-established adapted lens wearers he had an 80% to 85% success rate. Newer RGP wearer results were lower, he said, but that was because some patients did not adapt to rigid lens wear.
Dr. Byrnes fit 20 patients during a clinical trial. "Even advanced presbyopes who had to put glasses on for near really didn't mind. Early presbyopes — anyone up to a 1.50 add — had no problems," he said.
Fit lens slightly superior
Dr. Byrnes, who has worn the lenses himself for 9 months, offered several fitting tips. He fits the lens slightly superior and slightly temporal and 0.1 D steeper, but warned that if the lens is fit too steeply it begins to center, losing its movement and some of the add effect.
Also, Dr. Byrnes advised against refracting and checking the vision through a phoropter, "because you are limiting the head movement and the eye position," which may throw off the final correction.
He recommended trial fitting the lenses with fluorescein for best success.
"You get the best distance vision you can, forcing plus, so you're using the maximum plus with the least minus. Then you check their vision at distance and near, and do the same for the other eye," he said. "Then you'll find binocularly they'll improve maybe half a line or a line using both eyes."
"In my experience, this is the best thing we’ve got going for early and emerging presbyopes," said Dr. McMahon. "Historically, I have been skeptical of most of the multifocals. When this hits the market, we'll be fitting it routinely."
For Your Information:
- Tim McMahon, OD, can be reached at (312) 996-5410; fax: (312) 996-4908. Dr. McMahon has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned. Stephen Byrnes, OD, can be reached at (603) 434-4449; fax: 603-432-6059. Dr. Byrnes did not disclose whether he has a direct financial interest in the products mentioned in this article, nor if he is a paid consultant for any companies mentioned.
- Alan Sartain can be reached at Polymer Technology.
- The Boston MultiVision is available from Polymer Technology, 1400 N. Goodman Street, Rochester, NY 14609; (800) 225-1241.