CK for presbyopia approvable with conditions by FDA review panel

The procedure is an additional indication for Refractec’s ViewPoint CK System.

Issue: March 15, 2004

ByJeanne Gonzalez

GAITHERSBURG, Md. — The ViewPoint CK System was voted approvable with conditions by an independent review panel to the Food and Drug Administration in February. Indication is for the temporary induction of myopia of 1 to 2.25 D in the nondominant eye of patients with presbyopic hyperopia and presbyopic emmetropia. Patients must first complete a successful trial of monovision contact lens wear, which assists in predicting outcome.

Since the approval of the CK System to induce monovision for the temporary treatment of hyperopia, more than 25,000 procedures have been performed in the United States, said Jon Hayashida, OD, vice president of clinical affairs at Refractec. Clinical investigators Marguerite B. McDonald, MD, and Daniel S. Durrie, MD, presented data on the clinical safety and efficacy of the procedure.

The Ophthalmic Devices Panel voted that the FDA should approve the indication once additional labeling changes are made. The panel decided there was reasonable assurance of safety and efficacy and stated that the benefits outweigh the risks of the procedure. The device is already on the market for the temporary treatment of hyperopia, and the technology has a good reputation.

In its decision, the panel requested further data on the maintenance of patients’ depth perception preoperatively with spectacles and postoperatively with monovision. The panel wanted data on the treatment effect for emmetropia and hyperopia and more information on spot pattern effectiveness. It requested data on the worst cases and asked for more data on the effects of near vision in the trial.

Nystagmus and prior incision surgery were considered contraindications for labeling. The panel also added the possibility of keloids from the procedure.

Treatment for undercorrection was questioned by the panel, but Dr. Durrie said re-treatment involved rotating the treatment by 20.5º and adding eight spots or doing a laser procedure.

Patient education important

Although monovision using contact lenses or refractive surgery has established effectiveness in treating presbyopia, it is not without complications, said Mark Bullimore, MCOptom, PhD, a consultant for Refractec. This presentation on monovision contact lenses was given by Dr. Bullimore to give the panel some basis with which to compare CK, Refractec officials said.

“Even in satisfied, successful monovision patients, we can find decreased contrast sensitivity and reduced stereopsis in some patients due to the monocular blur,” Dr. Bullimore said.

Glare and night vision problems have also been reported. He stressed the importance of careful prescreening of patients and a successful trial of monovision contact lens wear or a history of it. He said that reading additions greater than 1.5 D to 2 D can result in loss of binocular summation and have associated problems.

Preoperative patient education of the procedure and related risks is important. Although the procedure is temporary, it should not be interpreted as a reversible procedure or a stable one, Dr. McDonald said. Patients should also know that the long-term effects are unknown. Dr. McDonald said she has performed 500 to 600 cases, but none has returned for enhancement. She tells her patients that the effects can last between 5 and 10 years.

Dr. Bullimore said, “Our patients need to understand that the course of monovision is a compromise … there’s a potential for symptoms and a possible need for continued use of spectacles, though the need would be substantially reduced.”

Safety

The clinical trial, however, showed safety and efficacy according to FDA standards. CK consists of applications of constant power in the optical zone designated by a corneal marker. The procedure steepens the central cornea but spares the visual axis, which Dr. McDonald noted was a potential safety feature. The range of correction is 0.75 D to 3 D, she said.

In the clinical trial, safety was evaluated by measuring best-corrected visual acuity, degree of induced cylinder, number of patient symptoms, complications and adverse events, Dr. McDonald said. There were 150 patients (188 eyes) with presbyopia enrolled. Minimum age was 40 years. The required refractive near correction was +1 to +2 D, she said.

Target correction was determined through a subjective refraction. Plus lenses were then applied until the best clarity was reached at 14 inches, Dr. McDonald explained.

“The improvement of uncorrected near acuity from baseline is particularly impressive considering that only 5% of eyes were J3 or better, and this increased by approximately 80% after treatment with CK,” she said.

Postoperatively, 1% lost more than two lines of BCVA, and no eyes achieved worse than 20/40, Dr. McDonald said. For best-corrected distance acuity, less than 5% lost more than two lines of vision, and less than 1% achieved worse than 20/40 at 6 months or later.

Incidence of induced cylinder was measured. Postoperatively, the increase in cylinder was small, and it decreased during the course of the study, Dr. McDonald said. Researchers observed no significant effect on uncorrected or best-corrected near visual acuity, she said.

Eighty-three eyes underwent contrast sensitivity testing with or without glare. Untreated fellow eyes were tested and used as controls. Binocular contrast sensitivity was tested under mesopic and photopic conditions, Dr. McDonald said. She noted that this particular part of the study was designed to evaluate the potential effects of monovision. Preoperative and postoperative results were compared. No change was found during the 12-month study follow-up, she said.

There were minimal complications and no sight-threatening events reported, Dr. McDonald said.

Efficacy

To evaluate efficacy, investigators determined factors related to the refractive outcome, Dr. Durrie said. The factors evaluated included age, spot pattern and preoperative refractive status, he said. There was no difference in outcome between patients with hyperopia and those with emmetropia, he said.

Spot patterns used were 8, 16, 24 and 32. Patients who received the 32-spot pattern showed a significant decrease in the refractive outcome, although a high percentage of eyes still achieved J3 or better, he said. J3 was the targeted outcome as determined by the investigators. Nearly all patients achieved J5, indicating functional monocular vision, he said. Eighty percent achieved J3 or better; 85% achieved binocular uncorrected near vision of J3 or better, he said.

“If we had tried to make every patient J1, many patients would have had more symptoms and anisometropia,” he said.

Investigators analyzed binocular uncorrected distance vision and uncorrected near vision, Dr. Durrie said.

“Over 80% of subjects achieved binocular uncorrected distance acuity of 20/20 or better and J3 or better near. If we look at the group of eyes with 8, 16 and 24 spots, excluding all 32-spot treatments, the number improves to almost 90%, to combine binocular uncorrected distance visual acuity and J3 or better, and 75% of patients achieving 20/20 and J2 or better,” he said.

“We achieved the target of near vision improvement monocular and binocularity while preserving excellent distance vision. As noted before, the eyes treated with 8, 16, and 24 spots are even better in all three analysis of effectiveness — monocular, binocular and when combined with uncorrected distance and near vision,” he said.

For Your Information:

Jon Hayashida, OD, vice president of clinical affairs at Refractec, can be reached at 5 Jenner, Suite 150, Irvine, CA 92618; 949-784-2600; fax: 949-784-2601.

Marguerite B. McDonald, MD, can be reached at 2820 Napoleon Ave., Suite 750, New Orleans, LA 70115; 504-896-1240; fax: 504-896-1251; e-mail: margueritemcdmd@aol.com.

Daniel S. Durrie, MD, can be reached at 5520 College Blvd., Suite 200, Overland Park, KS 6621; 913-491-3737; fax: 913-491-9650; e-mail: ddurrie@durrievision.com.

Mark Bullimore, MCOptom, PhD, can be reached at Ohio State University College of Optometry, P.O. Box 182342, 320 W. 10th Ave., Columbus, OH 43218-2342; 614-292-2020; fax: 614-688-5603; e-mail: bullimore.1@osu.edu.

Refractec Inc., manufacturer of the ViewPoint CK system, can be reached at 5 Jenner, Suite 150, Irvine, CA 92618; 949-784-2600; fax: 949-784-2601; Web site: www.refractec.com.