Everything you need to know about orthokeratology

Orthokeratology is the practise of wearing contact lenses at night in order to correct short-sightedness in the daytime. Sound too good to be true? And could it be for you? Here we explain the science behind this cutting-edge new eyesight technology.

What is orthokeratology and how does it work?

Orthokeratology (often referred to with the abbreviation ortho-K) consists in wearing semi-rigid contact lenses at night in order to correct your eyesight during the day, so meaning you don’t have to use your normal contact lenses or glasses. Ortho-K contact lenses are made to prescription and so carefully tailored to the geometry of your eye and the specificities of your particular sight deficiency that needs correcting. When you put them in your eye at night, the lens works like a mould which modify your corneal epithelium (the layer that makes up the surface of the cornea, situated just below the tear film). Some areas of the epithelium are flattened by the lens, whilst other areas are made larger. In the morning, the curvature of the cornea will have been fully corrected, making your sight clearer.


© Unsplash, by Hubble

When did orthokeratology start? 

In France, Orthokeratology has only been available for a few years. In fact, due to the history of its development, the practise suffers from a slight image problem, as the eye doctor Phat Eam Lim from Hendaye explains: “Ortho-K was invented more than 30 years ago. The initial idea was to make the patient wear a very flat contact lens both day and night, in order to distort the shape of the cornea. However, this did not in fact reshape the cornea correctly, and wearing a lens that is incredibly flat in comparison to the curve of the cornea is extremely uncomfortable. For this reason, their experiment was abandoned.” A few years later, the doctors realized that wearing a contact lens with a shape that was more adapted to the specific eye problem that needed correcting, and which are worn only at night (so the eye doesn’t move) could be a more comfortable and efficient way to correct eyesight. “The idea turned out to be substantiated by experiments and following the first conference on Ortho-K in France, we can say with certainty that it is an acceptable and scientifically-approved technique,” explains the ophthalmologist.

Can the lenses be painful?

Even though ortho-K lenses are more rigid than normal contact lenses, it doesn’t mean they cause discomfort, as Dr Lim affirms: “The technology was especially developed so they can be slept in, so yes, they are comfortable. When you close your eyes, you can’t feel anything.” However, if you wear the lenses during the day, to watch television or walk around, with your eye constantly moving, they can become uncomfortable. But this shouldn’t be seen as a negative: as don’t forget the lenses weren’t designed to be worn like this in the first place.


© Unsplash, by Hubble

Who are they for?

Today, people with poor eyesight have several options. “Generally, people opt for glasses, classic contact lenses or correction surgery. Orthokeratology is another alternative which has several compelling advantages”, argues Dr Lim. He explains: “For many reasons, several people can’t have their eyes operated on. This is the case when sight is still developing (as is often the case with young people), or when the cornea is too thin or unstable. Other people don’t want to recourse to surgery, often because they are scared of it or because it is costly. For some, the problem with contact lenses and glasses is that they can’t be used when playing water sports or contact sports. So, orthokeratology potentially offers a fantastic solution for many people. Some contraindications do exist (such as histories of surgery and autoimmune disease) but as when trying out all new eye correction approaches, an ophthalmologist should always be consulted on whether the method is right and safe for you.

Can children use orthokeratology?

Yes. From the age of 8 years, it is appropriate for children to use ortho-k, as long as they are able to wear contact lenses. For children who practice water or contact sports, it is an ideal solution. Ortho-k is particularly interesting as an eye correction treatment for children for another reason: “We have noticed that people with short-sightedness increases with age, and wearing ortho-K lenses can help to curb its development early on. This question is at the centre of much research, but it looks likely that the effects of ortho-K on the eyesight of children are extremely positive,” concludes Dr Lim.