At Zacks Eye Clinic in central London we have optometrists who specialise in fitting Orthokeratology (Ortho-K) contact lenses.
Orthokeratology, 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).

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).
Orthokeratology Fitting
Every patient who wishes to be supplied with Orthokeratology contact lenses requires a specialist orthokeratology fitting consultation in addition to the eye examination even if they are longstanding contact lens wearers. This is to ensure that the eyes are healthy and to take a series of special measurements to confirm their suitability.
Orthokeratology lenses are specially made and a collection appointment is required to check the fitting and instruct on usage. Patients are then asked to return the following morning for a check-up after the first nights wear.

Orthokeratology Aftercare
After the Orthokeratology fitting is completed, regular follow up, aftercare appointments are very important to monitor vision, and eye health. Scans are taken at each appointment to see how the contact lenses have been fitting. Aftercare appointments are usually recommended every six months, however, they may be required more frequently for young children or those patients in need of more careful observation.
Advantages of Orthokeratology:
- Good vision without spectacles or contact lenses throughout the day.
- Children can be treated effectively and there is increasing evidence to suggest that increasing myopia (short sight) is retarded (myopia control).
- Orthokeratology is not a surgical procedure and it does not cause the permanent hazy vision experienced by some patients following laser surgery
- Orthokeratology is modifiable and reversible meaning that changes in prescription can be easily dealt with
- Orthokeratology does not hurt
- Well established orthokeratology contact lens fitting techniques mean that there are very few risks.
- Patients with dry eyes are free from contact lenses during the day.



