Orthokeratology (ortho-k), involves the use of specially designed rigid gas-permeable (RGP) contact lenses to alter the shape of the cornea in order to reduce or correct myopia, hyperopia, and astigmatism. It has been practised for almost 40 years, but the results were quite variable and unpredictable. However, in the last ten years new technology has become available to accurately map the corneal shape and manufacture lenses that will achieve a controlled and precise reduction in the eye’s optical imperfection. In addition, new developments in lens materials have been made that enable safe overnight wear to be possible. The technique of Ortho-k is now a safe, viable and reversible alternative to refractive surgery. The cornea, whilst being mouldable, always returns to its original shape if lens wear is stopped. For this reason, lenses are always worn nightly, or alternate nights after the ideal corneal shape has been achieved in order to retain the effect. You simply sleep in your lenses, then wake up and remove them, and enjoy clear vision all day!
The main purpose of Ortho-K is to be free of both spectacles and contact lenses throughout the day. This freedom of clear vision appeals to spectacle and contact lens wearers and is ideal for:
The initial assessment appointment includes a full eye examination and computerised corneal topographical mapping. This gives the optometrist a chance to assess both the general condition and health of the eyes and also to determine the likely effect of the procedure in that individual. Ortho-K contact lenses, made from highly oxygen permeable rigid material, are then fitted using the results of the corneal map to gently reshape the cornea towards less curvature. These will be worn for an initial trial and the response evaluated. This will typically take place overnight with a review the next morning. The effect should be a reduction of the initial prescription with improvement in the unaided eyesight. The corneal health will be carefully evaluated to ensure that it is not compromised. Only when the patient demonstrates an excellent response to the orthokeratology trial will the treatment programme commence.