There are many studies that have been published in the medical literature proving the efficacy of Orthok in controlling myopia progression. This is a huge area of interest in recent years and there will be many more studies that will be published in time to come.
This website http://www.myopiaprevention.org/references_orthokeratology.html compiles quite an extensive list of studies that have been published. You can click on the links and read the full version and/or abstract of each study.
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