OrthoK can be though of as the optical equivalent of dental braces. Treatment involves overnight wear of rigid gas permeable contact lenses that gently reshape the surface of the cornea while sleeping.
Like Soft Multifocal Lenses, the idea is to create peripheral defocus and thereby reduce the stimulus to eye elongation. The advantage to this treatment is that upon waking in the morning, the contact lenses are removed and the cornea retains the molded shape for the rest of the day, eliminating the need for daytime glasses! This is ideal for active kids who may otherwise be limited by eyeglasses during sports and other activities.
Unlike braces, this reshaping is not permanent. The custom retainer lenses must be worn every night to maintain the effect. Studies show that axial elongation is slowed an average of 43% with this method but more recent data suggests it is much higher. Newer lens designs have demonstrated up to 90% reduction in progression in some cases.
For best results, it is recommended to start when the refractive error is less than 4.00D of myopia, and ideally for patients as young as 7-10 years of age. The efficacy and safety of these lenses is well documented, you can read more by clicking the links in this sentence.