What Is Orthokeratology?

Orthokeratology [or Ortho-K] is the programmed use of specially designed contact lenses to improve unaided vision by reshaping the cornea (front surface of the eye). Myopic [short-sight] and astigmatic [irregular surface] errors of the eye may be reduced or eliminated.

The first reports of corneal re-shaping came from China. The ancient Chinese are known to have placed sandbags on their eyes while sleeping as a remedy to myopia. Orthokeratology as we know it today was first used in the early 1960's. The technique has been refined over recent years, leading to a faster and more predictable outcome.

How Does It Work?

The cornea [the transparent tissue that contact lenses rest on] is important in determining how clearly an object is seen. If the shape of the cornea changes, so too does the clarity of objects. Orthokeratology lenses are designed to deliberately make changes to corneal shape [they flatten the cornea] so that people who are short-sighted are able to see distant objects more clearly.

At present orthokeratology does not benefit long-sighted people. Ortho-K lenses are worn while sleeping and removed on waking. They have a unique design, which generates pressure in the thin layer of tears under the lens. This gentle tear pressure, rather than the lens itself, is responsible for the subtle change in corneal shape. Ortho-K lenses are highly oxygen permeable enabling treatment to proceed relatively safely during sleep without the problems caused by a lack of oxygen to the cornea.

What Does Ortho-K Offer?

The main benefit of Ortho-K is to be free of artificial aids to vision such as glasses or contact lenses for the majority of, or possibly all, waking hours. Unlike laser surgery, the procedure is reversible and this appeals to many people who are wary of causing permanent change to their eyes.

Is Everyone Suitable?

No. At present the procedure may reverse up to 4.00 dioptres of short sight [myopia] and up to 1.00 dioptres of astigmatism. The procedure does not work as effectively on very steep or very flat corneas. In addition, there are other factors that may affect the outcome. These vary with each individual and include the rigidity of the cornea and the degree of interaction with the eyelid. Therefore, success cannot be guaranteed.

What Should Patients Expect?

Lenses are worn overnight, seven days a week, and removed upon waking. The effects of this procedure will be noticeable after the first night. However, in the first few days, the effect will wear off gradually throughout the course of the day. After about ten nights of lens wear, vision should be stable enough for most patients to be without glasses or contact lenses for the entire day. Patients will always be required to wear a 'retainer' lens, just as one would wear a retainer after orthodontic treatment. This retainer lens may be needed less frequently over time.

Why Consider Orthokeratology?

If you are a pilot, firefighter, or police officer and need to have a certain level of vision, Orthokeratology is a process that works well without damaging the cornea. If you have a desire to lessen your dependance on eyeglasses or contact lenses to see, Orthokeratology could be the answer.

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