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Star S2 receives approval for hyperopic astigmatism
The FDA’s decision was coupled with conditions to be included in the product’s labeling.
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WASHINGTON — In an unanimous vote by the Food and Drug Administration’s (FDA’s) Ophthalmic Devices Panel, Visx Inc.’s (Santa Clara, Calif.) Star S2 excimer laser system was deemed approvable for the treatment of hyperopia using photorefractive keratectomy (PRK). The approval, however, came with conditions including that 12-month data for refractive stability be included in the product’s packaging.
Sponsor presentation
The data presented to the FDA were results of a multi-centered, nonrandomized clinical trial for the treatment of hyperopia with astigmatism using PRK with the Star S2 excimer laser. A total of 172 patients were enrolled in this study, and data from 276 eyes were presented.
“Regarding uncorrected visual acuity [UCVA], over time we see that at 6, 9 and 12 months postoperatively, more than 49% of patients saw 20/20 or better,” said Richard E. Braunstein, MD, principal investigator for Visx. “And greater than 95% of patients achieved 20/40 or better without correction at 6, 9 and 12 months. This exceeds the FDA guidance level of 85% at 20/40 or better.”
According to Dr. Braunstein, results from clinical trials for UCVA manifest refractive spherical equivalent (MRSE) exceed the FDA guidance levels. Similarly, when the patients were stratified by preoperative sphere for UCVA of 20/40 or better, the FDA guidance level was exceeded at the 9- and 12-month time periods.
FDA guidance levels were exceeded for intended versus achieved correction -1 in ±0.5 D and ±1 D at 3-, 6-, 9- and 12 month points. These guidelines were exceeded with 90% of intended correction being achieved in patients.
In all PRK trials, according to Dr. Braunstein, there is an expected overcorrection at 1 month with patients approaching emmetropia and keratometric stability between 6 and 9 months postoperatively and between 9 and 12 months postoperatively. In this trial, 96.3% had less than 1 D of change in MRSE and average keratometry at the 6- to 9-month period. This number increased to 97% for the 9- to 12-month period.
Patient satisfaction
Psychometric analysis was performed as part of this clinical trial. Patients were asked to rate nine different aspects of their vision using a questionnaire, on a scale of 1 to 10, from poor to excellent. When patients were asked to evaluate their preoperative vision using their corrected vision and their postoperative vision using their uncorrected vision, illustrations demonstrated that postoperatively there were fewer “fair” or “poor” responses with an increase in the number of responses for “very good” and “excellent.”
The majority of patients were satisfied with overall sharpness, clarity and consistency of their vision and overall visual comfort. A similar pattern of responses was given with regard to reading in dim light, driving in daylight, night driving, driving with night glare and general vision in dim lighting.
Results vs. refractive guidance
Marc G. Odrich, MD, medical director for Visx, presented a summary conclusion of the trial. At 12 months postoperatively, none of the patients had a loss of more than two lines of vision. According to the guidance document for refractive surgery lasers, less than 5% of patients with a loss of more than two lines are acceptable. The recommended level of UCVA of 20/40 or better in more than 85% of patients was exceeded, with 98% of patients having UCVA of 20/40 or better at 12 months. Additionally, the guidance document recommends that more than one-half of study patients need to be within 0.5 D of intended correction.
According to Dr. Odrich, this study exceeds the guidance document with 61% of patients being within 0.5 D of intended correction. Greater than or equal to 75% of patients need to be within 1 D of intended per the refractive surgery guidance. Dr. Odrich demonstrated that 77% of patients at 12 months met this criterion.
Deliberations
During the discussions among FDA panel members, although the majority of patients had their vision stabilized, there was a subset of patients that remained unstable. Leo Maguire III, MD, asked the sponsor to clarify the standard deviation of MRSE. Dr. Odrich recognized that there is some refractive instability in some patients, but the fluctuation of refractive error in these “outliers” does not follow a specific pattern. However, despite patients’ continued refractive instability, they still continued to see well, Dr. Odrich said.
Unfortunately, a trend could not be identified by the clinical investigators as to why this refractive instability occurred. Dr. Maguire questioned how such information would be addressed in the labeling. Dr. Odrich could not provide an answer at that point in time and needed to collaborate with the entire sponsor panel for recommendations on how to include “outlier” information in the product labeling.
According to Dr. Odrich, this group consisted of nine eyes out of 207 patients at the last postoperative visit that at 12 months changed more than 1 D. Dr. Maguire proposed that the labeling list examples of the “outliers.”
Motion
FDA voting member Mark A. Bullimore, MCOptom, PhD, made the initial motion, declaring the Visx Star S2 approvable with conditions. FDA consultant Michael R. Grimmet, MD, seconded this motion. Conditions included the laser be indicated for the correction of up to 5 D of sphere and 4 D of cylinder with a maximum MRSE of 6 D. Additionally, Dr. Bullimore recommended that long-term stability and hyperopic changes of 0.5 D per year be included in the labeling.
The sponsor must meet the following conditions in order to obtain final approval. In the labeling, the company must stratify effectiveness data (stability/predictability) by attempted correction and present all statistically significant findings (that is, contact lens wear, race, sex). Stability data need to be included with a note that complete stability is not achieved within a 12-month period. Long-term hyperopic change of 0.5 D per year may be anticipated, and data need to be presented and stratified on the greater shift toward hyperopia with increased attempted correction.
For physician and patient labeling, there will be mention of the potential for instability with a definition and description of the “outlier” group. A clear description of procedure-related pain, epithelial healing, visual acuity recovery, visual functioning under dim illumination, need for spectacle wear for near and distance, presbyopia and photophobia will be included. Additionally, there will be a separate labeling booklet for hyperopia and hyperopia with astigmatism.
For Your Information:
- Richard E. Braunstein, MD, can be reached at 635 W. 165th St., New York, NY 10032; (212) 305-9535; fax: (212) 305-0900. Dr. Braunstein has no direct financial interest in any of the products mentioned in this article. He is a paid consultant for Visx.
- Mark A. Bullimore, MCOptom, PhD, can be reached at Ohio State University College of Optometry, 388 W. 10th Ave., Columbus, OH 43210; (614) 292-4724; fax: (614) 292-4949. Dr. Bullimore has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- Michael R. Grimmet, MD, can be reached at Bascom Palmer Eye Institute, 7108 Fairwar Dr., Ste. 340, Palm Beach Gardens, FL 33418; (561) 515-1500; fax: (561) 515-1598. Ocular Surgery News could not confirm whether or not Dr. Grimmet has a direct financial interest in any of the products mentioned in this article or if he is a paid consultant for any companies mentioned.
- Leo Maguire III, MD, can be reached at Mayo Clinic, Ophthalmology Department, Rochester, MN 55905; (507) 284-4152; fax: (507) 284-4612. Dr. Maguire has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- Marc G. Odrich, MD, can be reached at Columbia University, Dept. of Ophthalmology, 16 E. 60th St., Ste. 420, New York, NY 10021; (718) 601-8720; fax: (718) 601-6102. Dr. Odrich is the medical director for Visx.
- Visx Inc. can be reached at 3400 Central Expressway, Santa Clara, CA 95051-0703; (408) 773-7158; fax: (408) 730-1399.