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FDA approves CK for hyperopia and expands trial for presbyopia
Data on the first 50 presbyopic patients show little regression after 6 months follow-up.
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LOS ANGELES — Conductive keratoplasty has been approved for use in treating hyperopia in people older than 40 years of age. In a separate move, the Food and Drug Administration also granted Refractec permission to expand its clinical trial of the procedure for treating presbyopia.
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The conductive keratoplasty (CK) procedure uses controlled release of radio frequency energy to cause changes in corneal curvature. The FDA granted approval to Refractec, of Irvine, Calif., for its ViewPoint CK System for the temporary reduction of spherical hyperopia in patients who have a cycloplegic spherical equivalent refraction of 0.75 D to 3 D and 0.75 D or less of astigmatism.
In late November, an FDA advisory panel had recommended CK for approval for hyperopia. Final approval from the agency came in April. (See related article, Refractec’s CK for hyperopia approved by FDA )
Weeks earlier, the regulatory agency had granted the company permission to expand its trial of monovision correction of presbyopia to include 200 patients.
“This is a study using CK to induce monovision in people who are emmetropic,” said Robert K. Maloney, MD, one of the principal investigators in the study, in practice here. “It is a continuation of the study we have already done, the first 50 eyes in which we treated patients for monovision.”
The expanded study is just beginning enrollment, he said. At deadline no new patients had yet been treated.
Dr. Maloney said the visual stability after CK is no different with monovision compared to hyperopia.
“The [presbyopia] study is really a study of a new indication for CK, as opposed to a study of how well CK works. We already know that CK works,” he said.
“CK works well for monovision because of its safety. The problem with doing LASIK for monovision is that some of the patients complain of quality-of-vision problems. With CK, we see very good preservation of quality of vision.
“We are typically targeting about 1.25 D for monovision. That works well. Most patients in their 50s and some in their early 60s, even with –1.25 D, can get pretty good reading vision, good enough for most of their activities. So we find a high level of patient satisfaction,” Dr. Maloney said.
He said it appears there are no significant complications, probably because there is no flap to cut.
“In our FDA study (of hyperopia), which had more than 400 eyes, there was not a single serious complication. We think it is going to have a real place as an alternative treatment to LASIK for hyperopia and presbyopia,” he said.
However, they are still early in the learning curve for the procedure, he added.
Six-month data
According to information Refractec released to Ocular Surgery News, there has been little regression in the original 50 monovision eyes after 6 months of follow-up.
According to the data, 94% of treated patients are 20/40 and J7 or better after 6 months of follow-up, and 91% were 20/25 and J5 or better.
Seventy-four percent of the treated patients remain 20/20 or better and are J2 or better after 6 months.
Dr. Maloney discussed the 3-month results of the first 50 eyes treated at the 2001 American Academy of Ophthalmology meeting. He said CK does induce cylinder in some patients, and one of the treated eyes had 1.25 D of induced cylinder at 3 months.
“We don’t think this is too much of a problem, because you can put extra treatment spots in the flat meridian at the slit lamp to correct it,” he said.
CK is a safe procedure, according to Dr. Maloney.
“My personal opinion is that it is safer than LASIK. I don’t have a single one of my 50 or so CK patients complaining to me of dry eyes, and I don’t have a single one complaining of hazy vision. I think it preserves the quality of vision better because it avoids the visual axis, and it preserves the tear film better because we don’t interrupt corneal innervation,” he said.
Hyperopia, emmetropia
Dr. Maloney said both emmetropic and mildly hyperopic patients were included in the presbyopia study. In emmetropic patients, surgeons treated just one eye. In hyperopia, surgeons treated one eye for distance and one eye for reading.
The data Dr. Maloney presented at AAO were mainly on mildly hyperopic patients. He said they targeted —1 D in all eyes and that they came close to the target.
“At 3 months, almost 90% of our people are within 1 D or 0.5 D of our goal,” he said. “The stability was very good.”
Dr. Maloney said it was striking that between 1 and 3 months, 75% of treated eyes changed less than 0.5 D.
“With most forms of thermokeratoplasty [patients have] a large initial overcorrection, and then they regress over a month or two to the desired correction. They might be fine for a month or two, and then they start regressing to back where they started,” Dr. Maloney told Ocular Surgery News.
“In CK, we see less regression. The initial overshoot is much smaller, maybe 0.5 D, and the regression is much slower, with eventual stability out to 2 years being achieved,” he said.
Dr. Maloney said the amount of regression seen between 1 and 2 years with CK is about the same as that seen with LASIK.
Distance vision was also good, but this was not surprising because most patients were either emmetropic or mildly hyperopic preoperatively, he said. However, he added, near vision was “surprisingly” good, with 94% of eyes J3 or better by month 3.
“For good reading vision, we like to get them to J2, and 50% were J2 despite the fact that we only targeted –1.”
For Your Information:
- Robert K. Maloney, MD, can be reached at Maloney Vision Institute, 10921 Wilshire Blvd., Suite 900, Los Angeles, CA 90024; (310) 208-3937; fax: (310) 208-8058. Dr. Maloney has no direct financial interest in the products mentioned in this article. He is a paid consultant for Refractec.
- Refractec Inc., manufacturer 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.