We have optometrists who specialise in Orthokeratology (Ortho-K) at Zacks London Eye Clinics (Warren Street, Fitzrovia, London W1) and (Kings Cross, Islington, London N1) .

Orthokeratology (Ortho-K), also known as overnight vision correction (OVC) involves using specially designed rigid gas-permeable contact lenses to alter the shape of the cornea in order to reduce or correct myopia (short-sight). The aim of Orthokeratology (Ortho-K) is to be free of both contact lenses and spectacles during waking hours making it a viable alternative to refractive surgery. In the last few years, advances in technology have made it possible to accurately scan the cornea and manufacture orthokeratology contact lenses which achieve a controlled and precise reduction in spectacle prescription. New developments in lens materials enable this to be done safely with overnight wear which is why the procedure is sometimes known as overnight vision correction (OVC).

Most of the visual changes with orthokeratology occur rapidly in the first few days requiring frequent examinations and in some cases, progressive lens changes. Stabilisation procedures then follow at a slower pace over the next few months. The cornea is highly elastic, however and always eventually returns to its original shape. For this reason, retainer lenses are necessary to maintain the improvement in vision. They are worn either overnight or for a few hours during the day after the ideal corneal shape has been achieved.

Advantages of Orthokeratology:

• Good vision without spectacles or contact lenses for most of the day
• Children can be treated effectively and there is evidence to suggest that increasing myopia (short sight) is retarded
• It is not a surgical procedure and it does not cause the permanent hazy vision experienced by some patients following laser surgery
• It is modifiable and reversible meaning that changes in prescription can be easily dealt with
• It does not hurt
• Well established orthokeratology contact lens fitting techniques mean that there are very few risks

Web links:

• ORTHO K from No. 7
• BRITISH ORTHO-K SOCIETY