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Researchers: Ideal myopia-controlling contacts will target many mechanisms
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Paul Gifford, PhD, FAAO, and Kate Louise Gifford, BAppSc(Optom) determined through a literature review that contact lens wear for myopia control outweighs the risk in allowing the condition to develop, while further research is required to establish the length and stability of effect.
Research is growing to attribute a complex system of factors to myopia development such as: parental influence and ethnicity, environmental factors, peripheral refraction and binocular vision, according to the authors.
One option for controlling myopia progression is orthokeratology (OK). According to Gifford and Gifford, recent OK studies for periods of 2 to 5 years have elicited a 32% to 42% myopia control effect. The studies suggest that OK is effective in slowing progression for an initial period of up to 3 years of wear, but researchers are unsure how long thereafter wear needs to continue to maintain effect and whether a rebound effect is possible.
Multifocal contact lenses and simultaneous (dual-focus) designs and aspheric designs have also been influential in slowing myopia, according to the review.
The researchers explored patents to build a clearer picture of the future of contact lens design. Most patents explain a method for controlling peripheral refraction and vary between how this is achieved, they said. The variations arise in defining the peripheral refraction zones of the lens.
“Altering the periphery to control the optical effect creates significant challenges that need to be overcome to allow optical variation while standardizing factors like sagittal depth so as to allow consistent fitting independent of the optical effect,” the researchers wrote.
CooperVision (Fairport, N.Y.) defines a method using multiple sets of contact lenses to provide differing degrees of change to the peripheral refraction profile, according to the authors. The lens profile is altered until balance between the visual quality and myopia control is achieved.
Pharmacological factors, such as using the contact lens as an antimuscarinic agent delivery device, may also be essential, they said.
According to researchers, the ideal myopia-controlling contact lens must also target the following: induce peripheral myopia without compromising vision, reduce lag of accommodation and reduce near esophoria.
The contact lens should measure ocular biometrics and analyze surroundings to provide real-time advice and training in avoiding environments that increase the risk of myopia progression, they continued.
FDA approval can bring global recognition and indicate high product safety and efficacy, however the time and cost involved can be great.
Significant development is underway as the etiology of myopia becomes more recognized, toward creation of contact lenses that individually target myopia, they concluded. – by Abigail Sutton
Disclosure: The researchers reported no relevant financial disclosures.
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