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Corneal Refractive Therapy
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Last summer I printed an article on corneal refractive therapy (CRT).  Since I have had several patients ask about this exciting vision therapy, I felt it would be helpful to reprint the article again.

If you are nearsighted (myopic), distant objects are blurry while near objects are clear without your glasses or contact lenses.  Over the last several years, laser eye surgery has become a very popular method to correct nearsightedness.  As an alternative, a procedure called orthokeratology or corneal refractive therapy (CRT) is another option available to correct myopia.

CRT has been performed since the 1950’s.  Due to advances in materials used for this procedure, it has recently become a more reliable option for myopic correction.

To understand how CRT works, the principles of myopia must be explained.  Myopia is caused by the shape of the eyeball being too long, or the cornea (clear covering of the eye) shaped too steep.  Glasses and contact lenses work by bending the incoming light properly so that it is precisely focused at the back of the eye.  Since we cannot shorten the eyeball, laser eye surgery works on the principle of flattening the myopic cornea to correct one’s near sightedness.  CRT also flattens the cornea, but does so without surgery.  It is performed by using a highly oxygen permeable contact lens to gently flatten the cornea while you sleep.  Simply put, I like to think of it as braces for your eyes (as odd as that may sound).

These contact lenses are placed on your eyes immediately before you go to sleep and are removed shortly after waking up.  For the first one to three months, the lenses are worn every night only while sleeping.  Eventually the goal is to reduce the contact lens wear to two to three nights a week.  The lenses are not worn while awake.   Initially the sharpness of vision will fade towards the end of the day.  Once the corneal reshaping has stabilized, your vision will be crisp all day.

CRT is only effective for people with mild to moderate amounts of nearsightedness and low levels of astigmatism.  Your eyes should be free of any eye disease.  Unlike laser eye surgery, CRT is completely reversible.  Should you be unhappy with the results at any time, simply discontinue sleeping with the lenses and your original eyeglass prescription gradually return.  Recently a study in the United States has shown fantastic results with fitting children with CRT lenses in order to control myopia.

What are the risks of CRT?  Fortunately, the risks are extremely low.  Should the contact lenses not center properly on the eye, distorted vision will result.  Your optometrist performs a thorough fitting process to minimize this occurrence.  Anyone who wears contact lenses is always at risk of any eye infection.  That risk is slightly higher by sleeping with them.  Fortunately, with advances in the lens materials recently, CRT lenses are extremely permeable to oxygen which keeps eye infection rates very low.


A regular eye exam is a key part of good vision health. Use our find an optometrist directory to find an eye doctor near you and to schedule an appointment.