Orthokeratology (ortho-K, corneal refractive therapy) is a non-surgical alternative to laser surgery for vision correction. It involves the prescribed use of hard contact lenses (to be worn at night only) to remould the top surface of the cornea to correct myopic (short-sighted) and astigmatic (irregular surface) errors that would otherwise require glasses.
Ortho-K is similar to the use of dental braces to straighten crooked teeth. The main difference is that if a tooth is corrected for some months it will stay in the new position, but the cornea is highly elastic, and will gradually return to its original shape when the contact lenses are removed. Thus the overnight reshaping of the cornea is carefully calculated to give clear comfortable vision lasting all day long. The contact lenses are then reinserted at night and the cycle continues.
It is important that Ortho-K lenses are worn every night to maintain the ideal corneal shape, but the contact lens wear can be discontinued at any stage and after a few days vision will return to the pre-treatment status.
Who is suited for Ortho-K?
Ortho-K may be an appealing option for all people desiring freedom from glasses or contact lenses during the day, especially for sports persons (eg. swimmers, footballers), those who work in dusty or dirty environments, or contact lens wearers who suffer from intolerance due to air-conditioning, allergies, dry eyes etc. Most commonly it is used in children, teenagers to assist with myopia control.
At present the procedure is only suitable for people with low to moderate myopic (short-sighted) refractive errors and low levels of corneal astigmatism. The procedure does not work as effectively on very steep or very flat corneas. In addition, there are several unknown factors for each individual – the complexity of the corneal shape, the rigidity of the cornea itself and the degree of interaction of the eyelids. Thus the speed and extent of corneal reshaping will vary from one individual to the next. Your optometrist can advise you if this is an option for you following an eye examination.
Does Ortho-K have advantages over Refractive Laser Surgery?
Yes. Apart from being far less costly than laser surgery, Ortho-K is non-invasive. There is no loss of corneal tissue, no surgical risks, and above all the procedure is reversible (laser surgery is not).
Myopia Control and Ortho-K
Studies have shown that when Ortho-K is used in young myopes there can be a reduction of up to 50 to 60% in the rate of progression of the myopia. This varies from patient to patient but compares favourably with other treatment options for slowing myopic progression such as atropine eye drops and multifocal spectacle wear.
At an initial visit you are assessed for your suitability for Ortho-K. This will involve a thorough examination of your eyes and detailed measurements of the shape of your corneas. At a subsequent visit you will be fitted with a trial pair of contact lenses, taught how to insert, remove and care for the contact lenses. You will then commence wearing these lenses every night and your progress will be monitored with frequent reviews over the following days and months to ensure we achieve the desired outcome for your vision.
How long does it take?
Changes occur fairly rapidly over the first few days and weeks. Hence frequent examinations, multiple lens changes and assessments may be required. Trials are available. Personal retainer lenses will be prescribed for ongoing use, depending on how well you care for your lenses, lenses will last 12-18 months.