Myopia prevalence in U.S. adults has increased from 25% in 1979 to 41% in 2004, according to a review covering the development of orthokeratology.
Vision impairment is 22 times more likely in myopia higher than 10.00 D compared with those with 6.00 D of myopia, according to Lipson and fellow authors in a review of orthokeratology (ortho-K) and myopia progression.
The onset of myopia can be seen in newborns, but most cases are seen in school-age children, they reported.
Jones and colleagues found three distinct patterns of myopia development: those first becoming myopic around 6 to 7 years old; then, a group developing myopia around 10 to 12 years; and those who first show myopia in their teens, each with their own unique pattern of progression.
The rate of progression slows after 12 to 13 years of age, according to the authors.
A study by Cho in 2012 showed that earlier age of intervention would have greater long-term benefit in limiting the ultimate level of myopia.
The first ortho-K lenses were created from polymethacrylate in the 1960s. The late 1970s saw a new era of contact lens materials, according to researchers, for gas-permeable lenses from new plastic materials.
In 1989, the first reverse geometry lens was developed by Stoyan and Wlodyga.
Contex Inc. (Sherman Oaks, Calif.) obtained FDA approval for a daily-wear ortho-K design in 1998. “
It became apparent that mapping the entire corneal surface before and after ortho-K treatment was critical to achieving optimal results,” authors wrote.
Current technological advances allow for corneal topography for ortho-K to obtain accurate baseline measurements, determine initial lens selection, design initial lenses, monitor topographic changes after ortho-K lens wear and accurately monitor lens treatment/position over many years of lens wear, they wrote.
Ortho-K lenses represented more than 5% of the U.S. GP lens market in 2011 and have grown to about 19% in 2016, they reported.
Hyperopic ortho-K reverse the pattern of flattening, with steepening centrally and flattening in the midperiphery, the authors wrote. Far less is known about the mechanisms that elicit these corneal and morphological changes.
Studies and meta-analyses on myopia with ortho-K have shown a 40% to 60% mean reduction in rate of refractive change compared with controls using spectacles to correct myopia, according to the authors.
While ortho-K has a significant effect on myopia progression, its results vary with individuals, they added.
Further, the authors added that the exact location or amount of peripheral myopic defocus that will result in the best control of myopic progression has not been determined.
“Ortho-K is safe and effective in children ... but requires a specialized process requiring practitioners to seek specialized training, certification and practical experience to become skilled in fitting and management of ortho-K patients,” they concluded. – by Abigail Sutton
Disclosures: Lipson is a consultant to Bausch + Lomb’s Specialty Vision Products Division. Please see the full study for remaining authors’ financial disclosures.