British Contact Lens Association

Orthokeratology

Orthokeratology or ortho-K (also known as corneal re-shaping or overnight vision correction), is the use of specially designed rigid gas-permeable (RGP) contact lenses to alter the shape of the cornea (the transparent front part of the eye) in order to reduce or correct low levels of myopia (short sight). The procedure may also be effective with low degrees of astigmatism (generally caused by an irregular cornea).

Orthokeratology lenses are worn nightly or on alternate nights and removed in the morning. The aim is to correct vision without the need for spectacles or contact lenses during the day. Because the effects on the shape of the eye are temporary, the eyes return to their original shape and prescription if the lenses are left off for a few days.

The main advantage is that contact lenses are not worn during the day, which is particularly useful for some activities, such as water or contact sports. Since it’s possible to see both with and without the lenses, they correct vision around the clock.

According to the British Orthokeratology Society (www.boks.org.uk), the procedure works best for people who have up to about -5.00D of myopia with no more than -1.50D of astigmatism.

If you’re interested, we recommend that you consult your eye care practitioner to discuss the procedure and whether you’re suitable, although not all practitioners have the expertise or equipment needed to undertake this procedure. Even if you’re within these prescriptions, some people are more successful with orthokeratology than others and it is currently not possible to predict who will achieve a better result. If you’re longsighted (up to +3D) or more shortsighted (up to -10D) you may still be suitable but the procedure can be more complex.

If you need separate distance and reading prescriptions, bifocals/varifocals or take your glasses off to read, then orthokeratology may not be the most appropriate option, although this is best discussed with your eye care professional. Orthokeratology could correct your distance vision but you may still need reading glasses, or it could be used to correct one eye for distance and one for near, as with other types of contact lenses.

If you’re over the age of about 45 and need bifocals/varifocals or a separate prescription for reading (or take your spectacles off to read) having orthokeratology in both eyes will affect your reading too. If you’re treated so you are not shortsighted for distance and you would previously have removed your distance glasses to read, you’ll need to wear reading glasses instead. You may find this is more inconvenient than simply removing your glasses to read.

While orthokeratology can be effective at temporarily reducing or eliminating short sight, claims that it slows or controls the progress of myopia are as yet not supported by large-scale, long-term studies. The incidence and prevalence of eye infections with these lenses is not known. It is also not known whether the risk of infection is greater for children than adults.

If children are fitted with these lenses, parental involvement and monitoring of care procedures is essential.

Regular aftercare examinations (ideally at least every 6 months) are required after the fitting is completed, including assessment of the condition of the contact lens and the lens case. As with all contact lenses, it’s important to follow your practitioner’s recommendations on lens wear and care.

Ask your BCLA contact lens practitioner for more information on the different types of contact lenses and to help you decide which is best suited to your needs