Corneal Refractive Therapy (CRT) / Orthokeratology
CRT / Orthokeratology is the use of contact lenses to remold the shape of the cornea to reduce or correct myopia (near-sightedness) and astigmatism (irregular surface of the cornea). In some ways, this is similar to the use of dental braces by an orthodontist to straighten crooked teeth. The main difference is that if a tooth position 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, retainer lenses are worn while sleeping at night. Retainer lenses are prescribed after the ideal corneal shape or maximum change has been achieved.
Why have Orthokeratology done?
The main purpose of Orthokeratology is to be free of both contact lenses and spectacles for the majority of or possibly all of the waking hours. While this is ideal for sports enthusiasts or those who work in dusty, dry or dirty environments, for others it is simply the appeal of being free of corrective lenses during the day that draws them to the procedure.
What does the procedure involve?
First, there is an initial assessment appointment. This gives us a chance to both assess the general condition and health of the eyes and also to discuss the likely effectiveness of the procedure in your own case.
We use computerized corneal topography to photograph the eyes in a quick and painless procedure. The result is a color map of the corneal surface. This allows us to choose the specifically designed therapeutic lenses that will best work for you, and also allows us to detect conditions such as keratoconus or astigmatism. Additionally, these maps, which are saved and kept on file, allow us to trace the changes in your corneas over time.
A series of therapeutic lenses made from high oxygen permeable rigid materials are then fitted in progressive stages to gently reshape the cornea. This reduces myopia and astigmatism while dramatically improving unaided eyesight. Most of the visual changes occur rapidly in the first few days and weeks. Stabilization procedures then follow at a slower pace over the next few months. The program length varies between 3 to 4 months depending upon the degree of visual error and the rates of change. After treatment and maximum results are achieved, retainer lenses are worn to stabilize the new corneal shape. Failure to wear the retainer lens on an ongoing basis will result in the return to the pre-existing prescription. Retainers may be worn during sleep. There are a number of new brands now available that allows us to treat a larger number of patients.
What are the disadvantages of CRT / Orthokeratology?
- You must be prepared to allow for three to four visits over three to four months.
- Retainer lens wear is essential or the cornea will revert to its original shape.
- The degree of success is high but cannot always be guaranteed.
- The rate of improvement varies from one person to the next.
- You must be prepared to follow Dr. Paul’s instructions implicitly for the best results.
CRT / Orthokeratology has also been shown to slow the progression of nearsightedness in children and teenagers. Previously, if you were nearsighted and wanted to see clearly during the day, your options were glasses, contacts or laser surgery. CRT offers a new non-surgical solution. No more worry about broken frames or torn contact lenses. Additionally, while LASIK has been approved only for those over 18 years of age, CRT is ideal for our under younger patients who are active in sports and do not like the hassle of glasses or contacts.
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