New Zealand lens system may offer practitioners a better way to fit keratoconus patients

Issue: June 1997

HAMILTON, New Zealand — A new lens fitting system developed by New Zealand optometrist Paul Rose, OD, is giving exasperated practitioners who manage keratoconus patients a better way to provide these patients with good vision.

Dr. Rose, a member of a two-person practice here, is the designer of the Rose K Keratoconus Lens — a system of fitting and approaching patients who have a disease that often leaves contact lens fitters frustrated and the patients with badly damaged corneas.

Dr. Rose discovered more than a decade ago the drain on time that accompanies fitting keratoconus patients, which made up a major part of his practice. "It was very time consuming. If it hadn't been for the other parts of my practice, I would have had some trouble getting by," he said.

He also knew the challenges and rewards of dealing with keratoconus patients: "If you don't see well, there are many things you can't do, so there's a lot of satisfaction in making these patients happy," he said.

Dr. Rose sought a way to be more financially efficient, as well as a method of helping practitioners — even those who see only a few cases a year — fit keratoconus without ending up with gross corneal problems from poorly fit lenses.

Part of the problem was that practitioners would use conventional lenses and designs. "You have to go to a specific design for keratoconus," he said.

Different designs for different stages

Ten years ago, Dr. Rose began looking at different designs and saw how they worked for different stages of the disease. He retrospectively analyzed his last 300 fittings, in which he had designed specific lenses, optic zones and secondary curves with edges and lifts, and created particular widths in the secondary curve and particular sags for each patient.

His research revealed that as the disease progressed, the optic zone had to get smaller. "Although we knew that, typically keratoconus sets were all on one optic zone," Dr. Rose said.

The static optic zone penalized early keratoconics, who did not get a large enough optic zone to see through, while it was too big for advanced keratoconics.

"A large optic zone is better for vision, but a small optic zone is better for fit," he said.

Twenty-six lens system

After going through 700 lenses and 12 designs, he came up with a set of 26 lenses — the Rose K lens system. He underwent a 2-year development stage to perfect the lenses with Corneal Lens Corp. in Christchurch, New Zealand. He sent the lenses to New Zealand's six leading hard lens fitters and asked them to evaluate the lenses. Five years ago the lenses emerged on the New Zealand market, he said, and currently 80% of all keratoconics in New Zealand are fitted with them.

Several years ago, during a visit to the United States, Dr. Rose began working with Lens Dynamics of Lakewood, Colo., which developed new lathe software to manufacture the lenses. The lens received Food and Drug Administration approval for U.S. marketing in 1995.

Fitting advantages

Fitting the Rose K lens starts with the trial set. "You cannot fit keratoconus empirically, even with corneal topography," he said. "You still cannot fit these people optimally without putting a lens on the eye."

In the trial set, the power increases as the base curve steepens "because as you steepen the base curve, you effectively make the eye more myopic." Older keratoconus sets did not include this, which led to many rejections because of poor power and fitting assessment.

Fitters then evaluate the lens centrally, looking for light touch on the apex of the cone. The set, which runs from a 5.1-mm to a 7.6-mm base, enables fitters to achieve the proper fit. Then fitters evaluate the peripheral fit, "which is different from most systems where you try to do everything at once," he said.

Dr. Rose designed the peripheral edge lift for three groups of patients. The "standard" lift works for about 60% of patients. A second group, those typically with nipple cones, needs a lens with more peripheral lift, and a final group, usually with early oval cones, requires less lift in the periphery. The lens can be ordered with different edge lift with the same base curve, enabling practitioners to "fit about 90% of all keratoconus patients who come through your door," he said.

For patients who need even more peripheral lift, Dr. Rose also designed the lenses to accommodate lifts of up to 3.0 mm flatter in the peripheral system than standard. An ideal fluorescein pattern should show a band of fluorescein about 0.8-mm wide around the lens edge.

With the Rose K, a change in the base diameter of the lens also changes the optic zone, secondary curve and edge lift. "If you change any diameter, then all the curves change," he said. "It's a complicated lens in that respect, but all practitioners do is order the base, the diameter, the edge lift and the power they want. The lab does the rest."

Lens Dynamics has established a strategic partnership with Bausch & Lomb to distribute the lenses, said Al Vaske, president of Lens Dynamics. The company will use the Boston ES material for Rose K lenses and distribute the lenses through Polymer Laboratories.

U.S. clinicians find success with system

The company has sold about 500 trial sets, and many U.S. fitters have given glowing reports. "It is my lens of choice for keratoconus patients," said Lee Rigel, OD, clinician from East Lansing, Mich. He has worked with 15 to 20 patients during the past 9 months and said, while the lenses can be ordered in any diameter, he has not found a need to vary from the standard fitting set.

Dr. Rigel found comfort to be a major advantage of the lens. He said that in the past small fitting lenses have been irritating to keratoconus patients. "It seems to give both the acuity and the comfort. It is truly remarkable."

Patrick J. Caroline, COT, of Portland, Ore., has worked with the lens for 2 years in more than 150 patients and has had great success with it. "We've had great clinical success with it in virtually all stages of the condition," he said.

Mr. Caroline said because of the comfort, patients get an extra 2 to 3 hours of wear out of the lenses. "That takes them up to all-day wear. Instead of taking the lens out at 7:30 p.m., they can wear it until 10:00 p.m.."

Mr. Caroline said he has not had to modify the lenses: "With previous lens designs, we had to do a lot of in-office modification." With the Rose K, he said, "it's very rare that we have to modify."

If he needs a change, Mr. Caroline reorders a lens from Lens Dynamics through the warranty. The only disadvantage Mr. Caroline cited was that the lenses can be expensive for the patient: about $70 a lens. "The Achilles heel of the design is the price," he said.

However, he said this has not been a problem because most insurers will cover keratoconus fits. "It's not an optical condition, it's a medical condition," he said.

In managing keratoconus patients, Dr. Rose said he tells patients they must come in every 6 months — and he recommends they see someone else if they will not agree to this schedule. Also, he tells them their lenses should be polished every 6 months because of the tendency of keratoconics to build up lens deposits.

For Your Information:
Paul Rose, OD, can be reached at Rose K International Ltd., P.O. Box 9111, Hamilton, New Zealand; (64) 7-847-3195; fax: (64) 7-847-2878. Dr. Rose has a direct financial interest in the Rose K lens. He is not a paid consultant for any companies mentioned in this article.
Lee Rigel, OD, can be reached at 310 West Lake Lansing Road, E. Lansing, MI 48823; (517) 337-8182; fax: (517) 332-0038; e-mail: visioncare@voyager.net. Dr. Rigel did not disclose whether he has a direct financial interest in the products mentioned in this article or if he is a paid consultant for any company mentioned.
Patrick J. Caroline, COT, may be reached at the Oregon Health Sciences University, Casey Eye Institute, 3375 S.W. Terwilliger Blvd., Portland, OR 97201; (503) 494-5536; fax: (503) 494-4286. Mr. Caroline has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
Al Vaske an be contacted through Lens Dynamics Inc.
The Rose K Keratoconus Lens system is available through Lens Dynamics Inc., 8600 W. 14th Ave. Suite 2, Lakewood, CO 80215; (800) 228-2691; fax: (303) 274-6707; e-mail: alvaske@lensdynamics.com.