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Understanding Corneal Refractive Therapy (CRT) Management

Corneal Refractive Therapy contact lenses are a unique rigid gas permeable design that temporarily corrects nearsightedness by gently (and reversibly) reshaping your cornea while you sleep. You may then go throughout the day without wearing contacts or glasses and see great!

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What is CRT?

Corneal Refractive Therapy, commonly called CRT, is a method used to correct myopia (nearsightedness) or astigmatism by wearing rigid gas permeable contact lenses overnight, so that no corrective lenses are needed during daytime hours.

Gas permeable (GP) lenses specialized for CRT are inserted at bedtime and worn as you sleep. Throughout the night, the lenses reshape your cornea gently so that your vision becomes clear on the following morning. The correction is temporary, and ideally no eyeglasses or contact lenses will be needed on the next day or two. In order to maintain sharp visual acuity on a daily basis, you need to wear the CRT reshaping lenses every night.

Presently, CRT can correct nearsightedness up to approximately -4.00 and small amounts of astigmatism.

Candidates for CRT

CRT is very suitable for nearsighted people who are not appropriate candidates for vision correction surgery, such as children. Individuals of all ages with healthy eyes can try CRT, namely because it can be discontinued at any point without permanent effects to the eyes.

People who require vision correction and engage regularly in sports or work in extremely dusty, dirty environments will also appreciate the convenience of CRT.

Vision Results from Corneal Refractive Therapy

Paragon adSuccess rates for CRT are generally higher for more mild vision prescriptions. The ideal goal is to provide 20/20 vision without any need for eyeglasses or contacts during the day.

According to FDA trials conducted on both CRT and VST lenses, more than 65% of CRT patients achieved 20/20 visual acuity. A whopping number of more than 90% of CRT patients achieved 20/40 vision or better (this is the legal requirement for driving without vision correction in most states). Consult with your eye doctor to find out if your vision prescription is within range for successful CRT treatment.

Note that although improvement in vision is generally reported within a day or two of wearing CRT lenses overnight, the full effects may not be experienced until the lenses are worn for a few weeks. During this transition period, your vision will probably not be as crisp as it was with regular contacts or eyeglasses, and glare or halos around lights may be visible. Until CRT works fully, a temporary pair of eyeglasses may be required for specific actions, such as driving at night.

How Does CRT Feel?

Although some people have trouble wearing regular gas permeable contact lenses during the day, CRT GP lenses are worn while sleeping – so discomfort and awareness of the lenses in your eyes is generally not an issue.

Is CRT expensive?

Professional fitting for CRT requires a series of visits to your eye doctor. A number of pairs of contact lenses are also generally needed. GP lenses that are special for CRT are more costly than standard contacts. In sum, the fees for CRT add up to a higher total than regular contact lenses.


Some consider CRT to be a non-surgical alternative to LASIK. Nonetheless, refractive surgeries, such as LASIK, are possible after treatment with CRT lenses. Yet because it works to reshape your cornea, you are required to stop wearing the lenses for approximately several months before undergoing LASIK. This allows your eyes to return to their original shape.

It’s important to inform your LASIK surgeon if you’ve been wearing CRT lenses, and you will be advised as to how long of a wait is necessary before having the laser procedure.

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