Sometimes a single pair will produce the desired effect but quite often it is necessary to fit a series of lenses in progressive stages gently to reshape the cornea to a shallower and more spherical curvature. As the myopia and astigmatism reduce, the unaided vision dramatically improves. The Ortho-K lenses are calculated to give good vision while worn and their sophisticated design generally makes them quite comfortable. Most of the improvement in vision occurs rapidly in the first few weeks, requiring frequent examinations to monitor progressive changes in the corneal shape. New lenses are ordered and supplied as necessary.
Stabilisation then follows at a slower pace over the next few months.
Overnight wear Ortho-K lenses were originally worn during the day, but recent experience has shown that overnight use gives several advantages. Overnight use is not the same as 'continuous wear' because the Ortho-K lenses are removed during the day. When the optimum result has been achieved, a final pair of Retainer lenses' is worn to stabilise the new corneal shape. The wearing time depends on several factors but the treatment aims to give good unaided vision for all or most waking hours. The Retainer Lenses are also worn either overnight or for just a small part of the day.