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FDA panel recommends approval for corneal refractive therapy device
Contact Lenses and Eyewear
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WASHINGTON — At its Jan. 18 meeting, the Food and Drug Administration’s Ophthalmic Devices Panel voted to recommend approval with conditions of Paragon Vision Sciences’ rigid lenses Paragon CRT and Quadra RG for overnight wear to reduce myopia.
Members of the panel voiced concerns that the corneal refractive therapy (CRT) study results contained a population smaller than they normally like to see, and that, in some situations, the temporary effect of the lenses could result in refractive changes beginning during the early evening.
Paragon presented a clinical study for the Paragon CRT lens that included 95 patients and showed that approximately 90% of overnight users achieved at least 20/32 vision for 8 to 24 hours.
Concerns, but approval
The data-focused panel was pleased, overall, with the data Paragon provided; however, the panel members felt practitioners should be careful to whom they prescribe the lenses. In particular, because the lenses are typically worn for 6 to 10 hours while the patient is asleep, the effect of CRT lasts between 8 to 24 hours, with the majority of the patients noticing regression changes between the 8- and 24-hour marks.
Panel member Arthur Bradley, PhD, was concerned that the effects of CRT would begin to regress during the early evening as daylight began to fade, when many commuters would be driving home from work. He asked if there was anything that could be done for patients who noticed that their refraction was regressing, since putting on their old spectacles or contact lenses would be useless due to their improved refraction.
William Meyers, PhD, Paragon’s vice president for Science and Technology, said that if patients found that they had regressed, they could reinsert the lenses and they would see clearly. He explained that the nature of the custom fit lenses and the tear film on the eye would correct their vision as a regular rigid contact lens would.
The panel was also concerned that Paragon supplied data only for the CRT lens and not the Quadra lens. Both lenses already have FDA approval for open eye corneal refractive therapy. James Saviola, OD, chief of the Vitreo-Retinal Division of the FDA, advised the panel that approvals for a reasonable range of design in the same material for an indication could be considered by the panel based on available data that supplemented the clinical trial being reported. The safety of the device could be established by the data presented and the supplemental data for the design variation could be used to support its efficacy. Since the lens was already approved for safety and efficacy for daily wear FDA studies, the Quadra lens was approved as well.
The panel voiced concerns that 35% of the original study participants dropped out of the study prior to completion. Mark Bullimore, PhD, former FDA ophthalmic device advisory panel member and consultant to Paragon Vision Sciences, pointed out that the discontinuation rate was slightly less than that reported by Prof. Kenneth Polse in the CLEWS I and II overnight RGP extended wear studies published in Ophthalmology in August 2001, “Discontinuation in Corneal Refractive Therapy appears to be consistent with the overnight wear of rigid gas permeable lenses made of the same material.” Also, the panel said the data included only adults. The panel refrained from approving the lenses for adolescents. Jerome A. Legerton, MS, OD, the clinical monitor for the investigation, stated that the sponsor will submit the analysis of the adolescent subjects as a supplement to the application upon their completion. The adolescent subjects were enrolled after the approval of an interim report to the FDA.
FDA conditions for approval
The FDA panel members voted 11 to 0 to recommend for approval the Paragon CRT lens for the temporary reduction of naturally occurring myopia from -0.5 to -6.00 D of sphere with up to 1.75 D of astigmatism in an overnight wear fitting program.
The Paragon Quadra lens was approved with conditions by a vote of 10 to 1. Michael Harris, JD, OD, voted against because of the absence of Quadra lens data.
The labeling for both lenses must state that the study population was mostly Caucasian and that the discontinuation rate of use was 34.6%. Paragon must also include a statement that corneal refractive therapy does not affect the magnitude of pretreatment astigmatism. Paragon must list transient changes in post-treatment best spectacle-corrected visual acuity and emphasize that lenses need to be worn each night overnight. Failure to do so can affect activities of daily living, and some wearers may need corrective lenses during the day.
Paragon must also state that 10% to 15% of the eyes did not achieve 20/40 uncorrected visual acuity, with the trend worsening for higher myopic errors. The company must add a caution statement that corneal edema is more prevalent with the use of the lens in high altitudes.
The Quadra lens received all the same conditions; however, Paragon must also submit further analysis of existing data to address effectiveness concerns.
For Your Information:
- Paragon Vision Sciences can be reached at 947 East Impala Ave., Mesa, AZ 85304; (480) 892-7602; fax: (480) 507-0232.