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Home » Eye Care Services » Orthokeratology (CRT & VST)

Orthokeratology (CRT & VST)

man removing contactOrthokeratology, commonly called ortho-k, is a method used to correct myopia (nearsightedness) by wearing rigid gas permeable contact lenses overnight, so that no vision correction is needed during daytime hours.

Gas permeable (GP) lenses specialized for ortho-k 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 ortho-k reshaping lenses every night.

At present, two brands of ortho-k contact lenses are approved for use by the FDA. Paragon Vision Sciences produces “Corneal Refractive Therapy” (CRT), and Bausch and Lomb manufactures “Vision Shaping Treatment” (VST).

Candidates for Ortho-K

Ortho-k 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 ortho-k, 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 ortho-k.

Vision Results from Ortho-k

Success rates for ortho-k 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 ortho-k patients achieved 20/20 visual acuity. A whopping number of more than 90% of ortho-k 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 ortho-k treatment.

Note that although improvement in vision is generally reported within a day or two of wearing ortho-k 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 ortho-k works fully, a temporary pair of eyeglasses may be required for specific actions, such as driving at night.

How Does Ortho-k Feel?

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

Is Ortho-k expensive?

Professional fitting for ortho-k 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 ortho-k are more costly than standard contacts. In sum, the fees for ortho-k add up to a higher total than regular contact lenses.

LASIK after Ortho-k

Refractive surgeries, such as LASIK, are possible after treatment with ortho-k lenses. Yet because ortho-k 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 ortho-k lenses, and you will be advised as to how long of a wait is necessary before having the laser procedure.

Frequently Asked Questions about Corneal Refractive Therapy (CRT) No Glasses, No Daytime Contacts, No Surgery … Just Good Vision.

Now you can correct your vision while you sleep with safe, non-surgical Paragon CRT therapeutic lenses. This treatment allows you to enjoy great vision 24 hours a day, without the hassles of glasses and daytime contacts. Eye irritation and dryness, frequently associated with contact lens wear due to dust and pollutants, are eliminated.

Paragon CRT leading-edge technology does NOT require any laser eye surgery. Recent clinical research combined with the latest corneal mapping technology, space age oxygen-breathing materials, and computerized manufacturing make correcting your vision while you sleep a reality!


Frequently Asked Questions about Corneal Refractive Therapy (CRT)


Q: What is Corneal Refractive Therapy (CRT)?

A: Paragon CRT is a unique rigid gas permeable contact lens designed to, non-surgically, temporarily correct myopia (nearsightedness) by gently and reversibly reshaping your cornea while you sleep. Paragon CRT lenses are made from a contact lens material that is safe for overnight wear. Each morning the lenses are removed, leaving you with excellent vision for the remainder of the day.

Q: Can everyone wear CRT lenses?

A: Not everyone can wear Paragon CRT. This lens is intended for individuals with low to moderate myopia (nearsightedness up to -6 diopters) and moderate astigmatism.

Q: How do I care for my lenses?

A:Your lenses should be chemically disinfected after every use (not heat). Your eye care practitioner will instruct you about what care system is best for you. Your lenses should be replaced as your eye care practitioner sees fit.

Q: How likely is it that CRT will work for me?

A: Of the 159 eyes targeted for 20/20 vision (who had this acuity with their best spectacles), 59% obtained 20/20 or better without other correction and 92% obtained 20/40 or better at 9 months. (20/40 vision is the acuity required in most states to drive without glasses). 67% Of the subjects obtained 20/20 vision in at least one eye (their better seeing eye) and 94% achieved 20/40.

Q: How long does it take to reach good vision?

A: Most patients have rapid improvement in the first few days of treatment and have achieved nearly their optimum vision in 10 to 14 days. A small percentage of patients will not improve enough to function under all conditions without additional correction.

Q: Is Corneal Refractive Therapy permanent?

A: No, it is temporary. If you stop wearing the lenses regularly while you sleep your lens-free vision will return to its original state in as little as 72 hours.

Q: What are some important things for me to remember?

A: If you feel like you are having a problem with your vision or contact lenses, immediately remove your lenses and call Dr. Noble or Dr. Simonson at 336-2020. Always follow the instructions your eye care professional has given you about lens wear, follow-up and care systems.

Q: What are the risks of wearing Paragon CRT?

A: There is a small risk involved when any contact lens is worn. It is not expected that the Paragon CRT Contact Lenses for Corneal Refractive Therapy will provide a risk that is greater than other rigid gas permeable contact lenses. Because this procedure is reversible some patients may notice changes in their vision late in the day.   The two most common side effects that occur in rigid contact lens wearers are corneal edema and corneal staining. It is anticipated that the same side effects will also occur in some wearers of Paragon CRT. Other side effects that sometimes occur in all contact lens wearers are pain, redness, tearing, irritation, discharge, abrasion of the eye or distortion of vision. These are usually temporary conditions if the contact lenses are removed promptly.   In very rare instances, infections of the eye, corneal ulcer, iritis, neovascularization, corneal scarring, permanent decreased vision may occur. The occurrence of these side effects should be minimized or completely eliminated if proper lens care is exercised.

Q: What do I do in the period of time between when I start Paragon CRT® and when I achieve treatment?

A: It is important to understand that for a time after you have begun treatment but before sufficient treatment is realized, your old glasses will no longer be the appropriate prescription. Your eye care professional will discuss what your options are for visual correction during that period of time.

Q: What if I have questions about Paragon CRT?

A: It is essential that you discuss any issues you may have about your eye health or contact lens wear with Dr. Noble or Dr. Simonson. If you need any further information about Paragon CRT lenses, please contact Ada Vision Center at 208-336-2020.

Q: Who should not wear Paragon CRT?

A: Persons who exhibit any of the following conditions should not wear Paragon CRT:

  • Inflammation or infection of the eye.
  • Any eye disease, injury, or abnormality that affects the cornea or surrounding tissue.
  • Any systemic disease that may affect the eye or be worsened by wearing contact lenses.
  • Allergic reactions of eye, which may be caused or exaggerated by wearing contact lenses or use of contact lens solutions.
  • Eyes that are red or irritated, or suffer severe dryness.

Q: What kind of experience does Ada Vision Center have with Paragon CRT?

A: The staff at Ada Vision Center is excited to provide this safe, effective, new technology to our patients. Dr. Todd Noble, Dr. Amber Simonson and Dr. Lauren Huber are three of only a handful of doctors in the state of Idaho that has been officially certified to design and fit the Paragon CRT therapeutic lens. We have extensive experience in fitting CRT lenses and have many happy patients currently undergoing treatment. We are thrilled with the effects this treatment has been able to provide to our patients.

Q: Is Corneal Refractive Therapy expensive?

A: Paragon CRT therapeutic lenses are specially designed for each patient, making them a little more expensive than glasses or daytime contact lenses. But, Paragon CRT costs only 25% - 35% what laser vision correction does, making it a very affordable option for most people.