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Experts outline parameters for myopia control trials
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SILVER SPRING, Md. – Patient selection, efficacy endpoints, acceptable rate of microbial keratitis and patient-reported outcomes are all crucial factors in a randomized controlled clinical trial designed to evaluate the effectiveness of a device to control myopia progression, according to expert panelists.
Representatives from the major optometry and ophthalmology organizations co-sponsored a workshop held last week at the FDA to suggest guidelines for future clinical trials involving contact lenses with this indication in children.
Sponsoring organizations included the American Academy of Optometry, American Optometric Association (AOA), American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery (ASCRS), the American Association for Pediatric Ophthalmology and Strabismus (AAPOS), the Contact Lens Association of Ophthalmologists (CLAO) and the FDA.
A panel that was moderated by Natalie A. Afshari, MD, FACS, of ASCRS, and Christie L. Morse, MD, of AAPOS, reached a consensus that study subjects should be between the ages of about 7 and 12 years old with a refractive error of about -1.0 D to about -4.0 D, spherical equivalent (as long as the astigmatism is less than 1.0 D) achieved through cycloplegic autorefraction – due to its reproducibility, Afshari said – using tropicamide as opposed to cyclopentolate. The panelists agreed that 1.5 D of astigmatism should be allowed, along with a maximum amount of 1.5 D of anisometropia.
Regarding additional eligibility requirements, progression of myopia would not be a factor, but subjects may not have participated in any previous myopia control treatment (such as atropine or bifocal contact lens wear), and, most importantly, Afshari said, the ethnicity of the trial should reflect the U.S. population and not just one group within the study.
A panel led by AOA President-Elect Christopher J. Quinn, OD, and Michael X. Repka, MD, MBA, the American Academy of Ophthalmology’s medical director for governmental affairs, debated the appropriate study design and parameters for clinical outcomes.
The panel agreed that the most appropriate control group would wear a single vision soft contact lens.
After a lengthy debate over whether refractive error change or axial elongation should be the primary effectiveness endpoint, the preference went to axial elongation, despite the fact that, “patients and parents understand refractive error change better than axial elongation,” Repka said as he summarized the panel’s consensus.
There was no consensus, however, on the clinically meaningful differences for the endpoints between or within study arms. General suggestions from the panelists and audience members included: less than 50% progression, less than 0.75 D of progression over 3 years or 30% of subjects seeing an effect.
Panelists preferred that a premarket study last 3 years, although they conceded that 2 years would be acceptable.
Regarding abstention from device wear to ensure stability of the refractive outcomes, some said 6 months was long enough, although 1 year “was preferred because of seasonal impacts,” Repka said.
This same panel also discussed an acceptable rate of microbial keratitis (MK) in this study population, which they agreed should be no greater than the current rates for contact lenses.
However, “it’s important that we have an approved definition of MK,” Repka said. “Without that, it would not be a comparable rate. One suggestion would be the definition taken from more recent publications.”
Repka said combining that with registry information and previous clinical studies should be an option.
The FDA believes patient-centric outcomes are “of paramount importance” when evaluating today’s medical devices, and this was the last topic debated by a panel led by Donald Mutti, OD, PhD, a professor at the Ohio State University, and CLAO’s Deepinder K. Dhaliwal, MD, Lac.
“The consensus was that the patient-reported outcomes should be centered upon symptoms,” Mutti said as he summarized the panel’s recommendations.
Michael X. Repka
Donald Mutti
Symptoms of interest would come from the patient and be related to wearing the myopia control device, he said, such as wear time, disability, sense of visually related quality of life and sense of responsibility of the subject.
Mutti noted that parents would be most qualified to comment on behavior that’s observable.
“Questions need rigorous development and need to be in proper terminology and at the cognitive level of the age of the child,” he said.
The panel also agreed that patient preference studies could be informative, but “as ancillary studies, framed in a language parents and children can understand and in terms of both benefit and risk,” Mutti said.
Enrollment and retention could be improved by studying why people dropped out in the past, using flyers, offering free comprehensive care and products, using social media, “deputizing” care providers, assisting with logistics such as providing transportation, requesting records from schools and approaching sports clubs, the panel concluded.
Parents, children and potential advocacy groups could be better engaged by understanding what parents want through focus groups, understanding why parents might not want to participate, and involving pediatricians and local providers as sub-investigators. – by Nancy Hemphill, ELS, FAAO
Disclosures: Mutti reported that he has received research materials from Bausch + Lomb and is an unpaid consultant to Johnson & Johnson Vision Care and Welch Allyn. The other moderators reported no relevant financial disclosures.