July 01, 1997
3 min read

Prism technology used in two new prescription lenses

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Patients with traumatic brain injury and stroke have seen better with the Hemispheric, or half-prism, lens.

JANESVILLE, Wis. — Two groups of low vision patients who previously had little freedom or hope for better vision are being helped by new prescription lenses that use prism technology. The Hemispheric Lens (half-prism lens) and Peripheral Field Loss Lens (channel lens) are manufactured by Inwave Optics Inc., in its Clearwater, Fla., facility.

The molded lenses consist of standard CR39 resin and accept normal tints and coatings. "The prism is molded into the lens," said David. K. Hendrickson, mechanical director for Inwave Optics.

The patient's prescription is then ground onto the lens surface. The lenses are available in powers of ±8.00 sphere and ±7.00 cylinder. Bifocals come in 25-mm round segs only, with +2.00 and +2.50 bifocal adds.

Like a side mirror

Mr. Hendrickson likens the hemispheric lens to a side mirror in an automobile. "We bisect the lens with a prismatic effect," he said. The prism picks up that field and moves the objects in that field toward the patient's usable field."

Michael R. Politzer, OD, a neuro-optometrist in private practice in Nashville, Tenn., has dispensed the hemispheric lens several times, with varying degrees of subjective and objective success among patients with traumatic brain injury and stroke. "These patients have a visual field loss. This lens does not bring that visual field loss back; rather, it allows the patient to function more efficiently, in spite of that loss," he said.

From a safety and accident perspective, however, "it's been a tremendous help and benefit to them," Dr. Politzer said. Many patients have been able to return to driving.

This spring, Lynne P. Noon, OD, in private practice in Apache Junction, Ariz., prescribed the hemispheric lens for a stroke survivor. Previously, the woman was unable to walk without using her husband's arm as support. She is now walking in the mall, with a mobility instructor. "She's very happy," related Dr. Noon, who said the woman came into the office for an entirely different reason.

Used by retinitis pigmentosa patients

Dr. Noon has also fitted several retinitis pigmentosa patients with the peripheral field loss lens. "They are very happy. It makes them feel that their world is more open," she said. "One patient can walk her dog again without using her white cane, because she can now see both sides of the sidewalk."

In addition to these patients sensing a new freedom, Dr. Noon is pleased that she has a new product to offer. Once a practitioner fits one or two of either lens, "it's very straightforward," she added.

However, older patients in general require more instruction on use. "But most people seem to adapt fairly quickly," Dr. Noon said. "They also can see the benefit right away — it doesn't take long for them to notice what the lens does for them."

Despite the benefits of both specialty lenses, Dr. Politzer said it is important for patients to receive extensive follow-up care and therapy. "Training and experience in the proper use of their aids is the difference between success and failure," he said. "Without the care strategy, the glasses will likely end up in the drawer."

Dispensing these lenses can also be a revenue enhancer, especially serving glaucoma patients. "The optometrist should now be able to build a very good rapport with the ophthalmologist," Mr. Hendrickson said. "It's a two-way street, but the one who benefits is the patient."

This fall, Inwave plans on introducing a central lens for patients with central field-loss conditions.

For Your Information:

  • David. K. Hendrickson is technical director for Inwave Optics Inc. The Hemispheric and Peripheral Field Loss Lenses are available from Inwave Optics Inc., 29 West Milwaukee St., Janesville, WI 53547; (800) 957-8400; fax: (608) 757-7133; Web site: http://www.inwave.com/optics/main.html.
  • Michael R. Politzer, OD, can be reached at Woodmont Centre, 102 Woodmont Blvd., Suite 120, Nashville, TN 37205; (615) 386-3036; fax: (615) 269-7820; e-mail: odmrp@aol.com. Dr. Politzer has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
  • Lynne P. Noon, OD, can be reached at Southwestern Eye Center, 110 South Idaho Rd., Suite 160, Apache Junction, AZ 85219; (602) 982-0241; fax: (602) 982-5458. Dr. Noon has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.