What is Orthok?
Orthokeratology is the use of contact lenses overnight to remould the shape of the eye to reduce or correct refractive errors of the eye. In some ways it is similar to the use of braces by an orthodontist to straighten crooked teeth. The main difference is that if a tooth is corrected for some months it will stay in the new position. The cornea is highly elastic, however, and always returns to its original shape. For this reason the lenses are worn typically every night as a retainer. Established wearers can often miss a night without any loss of optimal treatment.
Why have Orthok done?
The original purpose of Orthok was to be free of both contact lenses and spectacles for all waking hours. This is ideal for sportspeople, swimmers, dry eye sufferers, or those who work in dusty or dirty environments and may be appealing to other spectacle or contact lens wearers who wish to be free of their optical appliances.
Long term studies have now demonstrated that Orthok can significantly slow the progression of myopia (short-sightedness) in children. This has the added advantage of reducing the risk later in life associated with higher levels of myopia, such as retinal detachment. For more information on myopia control please visit http://www.myopiaprevention.org/.
Does Orthok have advantages over Laser surgery?
Is everyone suitable for Orthok?
Although not everyone who needs glasses or contact lenses for vision correction is a candidate for orthok we can now successfully treat a much broader range of refractive errors, ranging all the way from -10.00D to +5.00D. While high amounts of astigmatism can prove challenging, even moderate amounts can now be corrected.
In addition there are several unknown factors for each individual – the complexity of the corneal shape and the rigidity of the cornea itself. Thus the speed of corneal moulding varies from one person to the next. Whilst the success is very high, it cannot be guaranteed due to factors outside our control.
What does the procedure involve?
First an initial assessment appointment in order to assess the general condition and health of the eyes, take measurements and discuss the likely effectivity of the procedure in your own case
After taking detailed corneal measurements your Orthokeratologist will then design your custom retainer lenses. Very rarely an overnight trial with a generic lens may be needed to assess the corneas response and individual tolerability, however this can often be misleading as the custom moulds are much more comfortable.
Once the lenses are manufactured an appointment is scheduled to teach you how to insert, remove and care for the lenses. Overnight wear is commenced and a follow-up visit is scheduled in the morning after a few nights of wear. This is to check the corneal response and to identify and correct any early problems. Another morning appointment is scheduled following 2 weeks of wear. At this point full correction is expected to be achieved. A further check is then scheduled late in the day after a month to ensure the correction is lasting a full day. The lens design may be adjusted accordingly at any of these visits if optimal correction has not been achieved. In these instances further follow-up may be required to ensure the desired outcome.
As with any contact lens wear it is vital to ensure the health and integrity of the cornea at all stages. Over the first year many visits are involved. After the initial therapy an examination twice a year is considered essential to ensuring ongoing safety of the eyes and good vision.
What are the disadvantages of Orthok?