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Refractec’s CK for hyperopia approved by FDA
Conductive keratoplasty uses radio frequency energy instead of a laser to reshape the cornea without cutting or removing tissue.
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IRVINE, Calif. — Refractec Inc. has received regulatory approval for use of its Viewpoint CK system to perform conductive keratoplasty for hyperopia in patients over age 40.
Conductive keratoplasty (CK) employs the controlled release of radio frequency energy, instead of a laser or scalpel, to reshape the cornea. The minimally invasive CK procedure takes less than 3 minutes and can be done in the office.
The Refractec Viewpoint CK System received premarket approval from the Food and Drug Administration for the temporary reduction of spherical hyperopia in patients who have 0.75 D to 3.25 D of cycloplegic spherical hyperopia, with 0.75 D or less of refractive astigmatism in minus cylinder format, and a cycloplegic spherical equivalent of 0.75 D to 3.00 D. Patients must be 40 years of age or greater with a documented stability of refraction for the previous 12 months, as demonstrated by a change of less than 0.50 D in the spherical and cylindrical components of the manifest refraction. The magnitude of correction with this treatment diminishes over time, with some patients retaining some or all of their intended refractive correction, the approval notes.
Regression
In November, the FDA’s Ophthalmic Devices Panel had voted 9-1 to make Refractec’s PMA requests for conductive keratoplasty, using the ViewPoint CK System, approvable with conditions. Among those conditions was that the labeling include “for the temporary reduction of hyperopia.”
During the panel meeting in November, the panel expressed concern with the device’s stability. The 12-month data that Refractec provided to the ophthalmic panel did not convince panel members that the ViewPoint CK System could maintain a refractive change in hyperopes for more than a year. It was the impression of the panel that the ViewPoint CK System induced an initial overcorrection at the start of the procedure, and that patients had to wait for regression to occur.
But the panel said that the 12-month analysis of 171 eyes using the final nomogram showed that the procedure easily beat the FDA guidelines by showing that 91% of patients were corrected to 20/40 or better, 58% had a mean refractive spherical equivalent (MRSE) of 0.50 D or less and 91% had an MRSE of 1 D or less.
CK is performed using a controlled release of radio frequency energy delivered intrastromally via a probe tip. The thermal profile is homogeneous to approximately 80% the depth of the cornea with an average width of 450 µm and an average depth of 500 µm. The CK device places eight to 32 probe treatment application spots around the peripheral cornea outside the visual axis. The number of treatment spots is determined by the required refraction.
Treatment characteristics
The premarket approval of CK is based on a clinical trial of 401 eyes (233 primary and 168 secondary). Of all eyes treated, 358 eyes were available for analysis at 3 months, 352 eyes at 6 months, 350 eyes at 9 months and 344 eyes were available for analysis at 12 months. Accountability was 99% at 3 months, 97% at 6 months, 96% at 9 months and 99% at 12 months.
The Refractec data analysis was based on the refractive data at all follow-up examination time points (1 month, 3, 6, 9 and 12 months). At 12 months, this analysis showed that 318 of 344 (92%) eyes were corrected to 20/40 or better and 191 of 344 (56%) were corrected to 20/20 or better visual acuity without spectacles or contact lenses.
The study showed that all adverse events occurred at low rates (<1%).
Refractec said that long-term risks of CK for hyperopia have not been determined. The safety and effectiveness of re-treatment procedures with the Refractec Viewpoint CK System or other refractive surgical devices have not been established.
For Your Information:
- Refractec Inc., manufacturers of the ViewPoint CK System, can be reached at 3 Jenner, Suite 140, Irvine, CA 92618; (949) 784-2600; fax: (949) 784-2601. Web site: www.refractec.com.