Orthokeratology

Using contact lenses to remould the shape of the cornea (the front surface of the eye) to reduce or correct myopia (short sightedness), as well as astigmatism (the irregular shape of the eye) is called orthokeratology.

In many ways it is akin to using braces to straighten teeth, although whereas teeth usually hold their new position once straightened, the cornea is easily moulded and will always return to its original shape once the moulding forces have been removed. Thus retainer lenses are required after the corneal shape has been achieved and are typically worn betwen two and four nights per week or for part of each waking day.

Why corneal reshaping?

Orthokeratology allows those normally requiring glasses to be free of both contact lenses and spectacles for the majority of waking hours. This is ideal for sportspeople, swimmers and those who work in dusty or dirty environments. Others benefit from being free of any artificial aids during the day, enabling greater freedom to pursue activities without hinderance.

Can anyone have Orthokeratology?

No, whilst new lens designs and improved accuracy of corneal measurement has resulted in dramatic improvement in the effectiveness of this procedure, only prescriptions up to 6.5 dioptres of shortsightedness (myopia) and 2 dioptres of astigmatism can be treated.

The process

First Stage

An initial examination to access the general condition and health of the eyes. This also provides the opportunity to discuss the likely effectiveness of the procedure with more precise background information.

Trial Fitting

Using a computerised corneal mapping system, the shape of the cornea is measured and a lens is selected. This lens is worn overnight and the response of the eye to the lens is then measured directly. If only minimal change is observed, it is likely that the cornea was resistant to change. A second lens fitting is attempted or the procedure is terminated. As the cornea changes, new corneal maps are required to permit the calculation of the next lens. The cornea is gently reshaped to reduce its power.

Excellent vision and comfort are normally maintained whilst wearing the contact lenses. Most of the changes occur rapidly in the first few days to weeks. Hence, frequent examinations and lens changes are required initially. Stabilisation occurs over the next few months. Thus the Orthokeratology program runs for three to six months, depending upon the initial degree of myopia and the rates of change of the corneal shape.

Once maximum changes are achieved, retainer lenses are worn to stabilise the corneal shape. Overnight wear is generally required. Failiure to wear the retainer lenses on an ongoing basis will result in the return of the eye to its original shape.