Myopia typically occurs when the eyeball grows too quickly during childhood and adolescence, at around 6 to 12 years of age. As the eyeball grows the eye structures stretch in length. Earlier onset of myopia is becoming more common, likely due to kids' earlier access to handheld electronic devices and increased reading and learning at a younger age.
It is believed that the peripheral parts of the retinal tissues send stimulation signals to induce the growth of the eyeball. Ordinary spectacle lenses and contact lenses correct vision equally from the centre to the periphery.
Recent research has found that when the peripheral retina receives different light signals, via a modification of the optics of the corrective lenses or by changing the shape of the eye surface with orthokeratology, the stimulating signals to promote eye growth are suppressed, thereby slowing down myopia progression.