Corneal Refractive Therapy (CRT)






What’s Corneal Refractive Therapy?

Corneal Refractive Therapy overnight contact lens or Orthokeratology (ortho-k) lens is a non-surgical, non-invasive and reversible process which reshapes (flattens) the cornea of the eye using Rigid Gas Permeable contact lenses to reduce short-sightedness and astigmatism. Flattening the cornea reduces the focusing power of the eye. Since the amount of corneal flattening can be accurately controlled, it is possible to bring the eye into correct focus. After the contact lens is removed, the cornea retains its flattened shape for part or all of the remainder of the day.

A retainer lens must be used each night to maintain the corneal flattening, or the eye will revert to the pre-treatment level.

Who Is a Candidate?

·        Healthy eyes with low degrees of myopia/shortsightedness (up to -6 dioptres) and astigmatism.

·        People who participate in sports (for examples rugby, cycling and swimming), or who work in windy, dusty, dirty environments that can cause problems for regular contact lenses.

·        Some long term contact lens wearers develop sensitivity to their lenses which results in reduced wearing time.

·        People who are not eligible for LSIK refractive surgery.

·        For children and adults with rapid progressing short-sightedness (Myopia), CRT has been shown to slow or retard myopic progression. This may result in a lower prescription, so the child won't have to wear the thick lenses he might otherwise require by the time he/she is a teenager. 


What Results Can You Expect from CRT?

93 percent of suitable candidates achieved 20/32 vision or better, and 67 percent achieved 20/20 or better occurs in few months. Few adjustments of the CRT lens may be required to achieve this result. During this process, daily soft contact lenses can be used until 100% corneal reshaping occurs.

Most of the visual changes occur rapidly in the first few days and stabilization procedures then follow at a slower pace over the next few months. The program length varies between 3 and 6 months depending upon the degree of visual error.

When the maximum results are achieved, the final pair of lenses are worn to stabilize the new corneal shape.

The final wearing time depends on many variables, but the treatment aim is to have good unaided vision all or most waking hours, with Lenses being worn overnight. Some patients will be able to wear their Lenses every other night.


Does CRT hurt?


CRT lenses are worn during sleep and behind closed eyelids (i.e. no lid interaction with the lenses), hence most people have no comfort issues.



Is CRT permanent?


No, it is not. Discontinuing lens wear allows your eyes (corneas) to gradually regress to their original shape. The effect of CRT is reversible.


Should You Have CRT Instead of LASIK?

CRT works best for people who don't want to wear glasses or contact lenses all day, every day — but don't mind wearing contact lenses at night, or occasionally during the day.

If your primary goal is to be glasses- and contacts-free during the day, then CRT might be a good alternative for you. However, if you want to eliminate the bother of contacts altogether, then CRT is not likely to satisfy you.

CRT may be a good option if you suffer from dry eyes. It's been found that this condition is sometimes worsened by LASIK.

Unlike LASIK, CRT is reversible. If you try CRT lenses and later decide you want laser eye surgery instead, you can do that.

The advantages of CRT are non-invasive, reversible, does not hurt, affordable, slows down the progression of short-sightedness, can be performed on people of any age.




To find out whether your eyes are suitable for CRT, please book an appointment with Vicky, our NZ trained and registered optometrist and the authorized CRT specialist.


The cost of the initial appointment will be $90.


If you are a suitable candidate, then the cost of the initial appointment will contribute to the total cost of the treatment.

If you are not a suitable candidate, then we will discuss about other options of visual corrections.


The standard CRT treatment includes


·        Initial visual assessment and corneal contour measurements

·        Fitting and instruction appointments (second and subsequent appointments)

·        4 to 6 morning follow-up appointments

·        One pair of custom designed CRT retainer contact lenses.

The lenses will usually last 1 - 2 years, depending on the mode of wear, condition of the lens and also the type of lens material (few options available). The premium lens material is highly permeable to oxygen and hence it provides the best results in visual correction result and it also reduces the risks of eye infection.


The total cost of CRT treatment starts from $1480 (standard lens material).



When you ring us, please tell the receptionist that you are booking an initial CRT appointment which will take up to 60-90 minutes.


Now you can enjoy clear and comfortable vision with


No need of Laser Refractive surgery !


No more Glasses !


No more Dry eyes or Allergy with Contact Lenses !



Eden Eye Optometrists or  Ph 09 3093900


We are proudly to be the certified CRT treatment provider, so you can choose us with great confidence. We are also members of the Orthokeratology society of Oceania and the NZ Cornea and Contact Lens Society.

To find out more about CRT, please visit and

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