was established in the UK with similar objectives to promote orthokeratology as a new procedure to correct myopia. The OSO, formerly known as the OSA, is an Australian-based association of orthokeratology optometrists and researchers representing Australia and the South Pacific region. Research into slowing of myopia progression in children In 2006 and 2007, papers presented at the British Contact Lens Association and the Global Orthokeratology Symposium indicated the possibility of orthokeratology slowing or stopping myopic progression. This was found to be effective in children in Hong Kong and is the subject of wider study to verify this data. Multiple other research evidence suggest that the reduction in myopic progression is roughly 50%, comparable to that of 0.01% atropine treatment, with remaining uncertainty regarding possible rebound effect after the Ortho-K use is discontinued. Mechanism and use Tissue growth and propagation studies indicate that epithelial cells adjust growth in response to presence of a foreign material. CRT lens proximity to the cells therefore is thought to stimulate cell growth where less RoR proximity coincides with added growth and more proximity coincides with growth repression thereby creating a 'proximal pressure' on the epithelial cells. The orthokeratology website ortho-k.net explains in lay-terms that the mechanism behind ortho-k is that around 60% of the eye's focusing power is provided by the cornea, and this is extremely sensitive to very small changes: 6 µm flattening of corneal thickness (around 5% of the thickness of a human hair) results in 1 diopter of changed vision in myopia. Therefore, a specially shaped lens can be used to lightly press the cornea, causing it gradually to be reshaped to the correct shape for focused vision. The corrective effect lasts up to 72 hours once initially acclimatized, which is long enough to be a practical means of eyesight correction. There is some evidence (see above) that unlike other eyesight correction mechanisms, Ortho-K may also reduce future or ongoing eyesight changes or increased myopia, although this is still being researched. Risks are comparable to or safer than ordinary contact lenses, since they are typically worn for much shorter periods (6–8 hours rather than daytime or 24/7) and while asleep rather than while active. They also compare favorably to surgical correction since no surgery is involved, corrections to the eye's shape can be handled over time (surgery corrects vision at a single point in time, but post-operative ongoing changes to eyesight will