Paragon CRT FAQ

Frequently Asked Questions

Q: What is Corneal Refractive Therapy (CRT)?
A: Paragon Corneal Refractive Therapy (CRT) is a nonsurgical corneal reshaping process that occurs at night by highly specialized gas permeable contact lenses. This allows patients to have their vision corrected while they sleep and gives them clear vision during the day without glasses, contacts, or surgery. CRT has been shown to reduce the progression of nearsightedness or myopia in children and adolescents.

Q: Is CRT permanent?
A: This is a non-surgical process, therefore, after discontinuing the lenses, your vision may revert to its original status as soon as 24-72 hours.

Q: Who is a good candidate for CRT?
A: The lens was approved by the FDA in 2002 to correct for patients with low to moderate nearsightedness of up to -6.00 DS, and astigmatism of up to -1.75DC.  Your eye doctor will recommend this lens if you are a good candidate after a thorough eye examination.

Q: How quickly after beginning treatment can I achieve optimal vision?
A: Usually optimal vision can be achieved after 10-14 days and some patients may even be able to see clearly during the first few days.

Q: Is there any pain?
A: There may be initial awareness and adaptation in getting used to wearing a contact lens inside the eye, but the therapy should not be painful.

Q: How often do I replace my CRT lenses?
A: Lenses will become scratched or covered with protein build-up. Therefore, we recommend that the Paragon CRT lenses be replaced once a year for optimal eye health.

Q: Can I see with my CRT lenses in?
A: Yes, the lenses are designed to allow the patient to see if you awaken in the middle of the night or put them on before bed.

Q: Are there any risks to CRT?
A: Contact lenses are considered medical devices by the FDA. According to the "Safety of Overnight Corneal Reshaping Lenses" study done at Ohio State University, the risks with wearing Paragon CRT lenses were similar to overnight wear of silicone hydrogel contacts.

Q: My friend wears orthokeratology lenses from another optometrist's office. How is that different from Paragon CRT?
A: Orthokeratology is an overall term to describe the process of corneal reshaping through overnight wear of specialty contact lenses. Paragon CRT was the first FDA approved lens for overnight corneal reshaping. The benefits of using Paragon CRT are that should you move to another location, another CRT certified practitioner can also continue the evaluation and refitting if needed.

Q: If my child begins Paragon CRT at this age, does that mean he or she will have to wear them for the rest of adulthood?
A: There are many correction options for children who have worn CRT lenses. Many young adults choose to continue with their CRT lenses into adulthood. However, your child may eventually want to consider other refractive options at a later age (i.e. soft contact lenses, spectacles or refractive surgery). CRT lenses are safe to wear during adulthood as a form of vision correction as well.

Q: Once my child or myself is fitted with these lenses, does that mean it has reversed my nearsightedness?
A. Paragon CRT does not reverse nearsightedness, but it does give you clear, comfortable vision during the daytime without glasses, daily wear contact lenses or refractive surgery. Research is promising, showing about fifty percent less myopia progression in children using these lenses versus regular soft lenses or spectacles.

Q: Does CRT really slow or stop the progression of nearsightedness in children?
A: Current research is showing adequate safety and efficacy of corneal reshaping lenses for slowing nearsightedness in children. Two studies have shown that 75% of children could be candidates for CRT lenses. These studies were called the Children's Overnight Orthokeratology Investigation Pilot Study (COOKI) and Corneal Reshaping and Yearly Observation of Nearsightedness (CRAYON) study. The CRAYON study showed that over a two-year period, children that were undergoing overnight corneal reshaping showed about 60% less progression of nearsightedness compared to children in regular soft lenses. Current research with large scale studies shows promising results.

Q: How does CRT work?
A: CRT works by reshaping the cornea's top epithelial layer centrally causing a relative thickening towards the cornea's mid-periphery. The theory behind this therapy is changing the peripheral refraction of the eye with these specialized lenses to slow the progression of nearsightedness.

Q: How long has corneal reshaping technology been used?
A: In the United States, this method of vision correction has been around for at least forty years. However, Paragon CRT was the first lens to be FDA approved in 2002.

CRT Testimonials by patients and parents

"My daughter has been using CRT for 18 months. It works very well for her. Her prescription has not grown since the first exam. She takes good care of her lenses and we are really thankful to my doctor for keeping her seeing well. We are very happy with the CRT and her doctor." - Parent H.P., patient age 10


"[My son] loves CRT and it works wonders for him. He sees so clearly during the day and he plays better sports without glasses. Once in a while he skips the lenses overnight, but his vision stays just as good." Parent H.C., patient age 10


"I really like that I don't need to wear glasses at anytime, because glasses are not as convenient as contacts. I also like that my eyesight is not getting worse." patient L.W. age 14


"The staff  were all extremely helpful in fitting me with the CRT lenses." patient J.W. age 15.


"I like CRT lenses because I don't have the inconvenience of wearing glasses and I can play sports with more convenience." patient K.H. age 13


"CRT has been working great for my son. My son's vision is very stable, not worsening at all for 2 years." parent M.Z., patient age 8

"CRT technology is a boon for kids helping them in their everyday sports and other activities without the hassle of glasses or regular lenses. Our experience has been extremely positive with the friendly staff and experienced and understanding doctor. I keep recommending them to my friends. -parent N.S., patient age 10


"CRT works perfectly for my daughter. She's been using it one and half years. Her vision did not increase at all. Thumbs up! -parent A.Z., patient age 10


"I like CRT lenses because I don't have to wear glasses anymore, and that I don't have to carry them around." -patient A.G. age 11


"My son likes his CRT. He likes playing basketball and swimming. The eyeglasses or day-time contact lenses would not fit his sports activities." -parent H.Z., patient age 10.


"I love not needing glasses or contacts while at college.  I see perfectly." - patient age 21


"I love that I can water ski, and swim without needing glasses or contacts.  Makes everything much easier." patient age 23.


Useful website: Paragon Corneal Refractive Therapy (CRT)