CRT-on-eye

Home What are Ortho-k Lenses? How Do Paragon CRT® Contact Lenses Work?

How Do Paragon CRT® Contact Lenses Work?

Since its FDA approval for overnight wear in June 2002, over a million people enjoy their Paragon CRT® Contact Lenses. This therapeutic contact lens gently reshapes the cornea while you sleep to temporarily correct nearsightedness up to -6.00 diopters, and mild amounts of astigmatism. Many have found Paragon CRT® Contact Lenses to be the perfect solution for themselves or their loved ones vision. If you’re not a candidate for eye surgery or are unsure, then Paragon CRT® Contact Lenses may be a great option for you. If you or your child have been diagnosed with nearsightedness (or myopia), Paragon CRT® Contact Lenses offers a non-invasive and non-surgical treatment.

A New Option For Those Who Are Nearsighted (Myopia)

Are you wondering how orthokeratology works? Watch the video and learn the science behind our Paragon CRT® Contact Lenses. If you are one of the billions of people in the world who are nearsighted and you want the freedom from your daytime contacts or glasses, ask your certified eye care professional if Paragon CRT® Contact Lenses are right for you.

Nearsightedness and Your Cornea

Orthokeratology (Ortho-K) is a non-surgical treatment option that corrects nearsightedness and astigmatism using treatment lenses worn overnight. The lenses gently reshape your corneas while you sleep. Upon waking and removing the lenses, you will experience clearer vision without glasses or contact lenses throughout the day.

In a nearsighted eye, light from a far away object is focused in front of the retina, resulting in blurred vision. Traditional glasses change the direction of light before it enters the eye, allowing the image to focus on the retina for clear vision.

Unlike refractive surgery (LASIK), ortho-k is temporary, as continual use of nighttime treatment lenses is necessary to maintain its effect. It is an especially attractive option for those that are either apprehensive about or not a candidate for refractive surgery.




Paragon CRT® Contact Lens Design and Initial Fitting

Beyond a comprehensive eye examination, the following outlines the basic steps involved in the fitting process:

A corneal topography will be performed to determine the shape of your cornea and assist in the selection of an initial diagnostic lens. If necessary, additional diagnostic lenses will be prescribed until your eye care practitioner obtains the ideal corneal-treatment lens fitting relationship. It is believed that the ortho-k effect occurs in the corneal epithelium, which is the top layer of the cornea. The treatment lens is specifically designed to alter the shape of this tissue. As illustrated in this cross section view above, the treatment lens is flatter than the cornea at its center and takes a plateau shape toward its periphery.

Your eye care practitioner will provide a temporary pair of Paragon CRT® Contact Lenses that you will use during your initial treatment period.

Paragon CRT® Contact Lens Wear
While wearing the Paragon CRT® Contact Lenses, the surface differences between the lens and the cornea, forces the cornea (epithelium) to take on a new shape. The corneal tissue begins to take on the shape of the back surface of the treatment lens, which is designed to correct for myopia and astigmatism.

Paragon CRT® Contact Lens Removal
After wearing the lens overnight, the Paragon CRT® Contact Lens is removed revealing a new corneal surface shape. You should notice improved vision, however, during the first few days of treatment, and depending on your prescription, you may notice that the effect will fade quickly. However, with every successive night of wear, the effect should become greater and last longer. It will take between 7 to 14 days of treatment to obtain unaided-vision throughout your day.1

Paragon CRT® Contact Lens Long-term Treatment Effect
Your eye care professional will closely monitor your progress and make lens design changes when necessary.

Visit our Frequently Asked Questions to learn more about orthokeratology and determine if Paragon CRT® Contact Lenses are an option for you.


Schedule Your Appointment Today

Find a Certified Paragon CRT® Contact Lens Eye Care Professional Near You


  1. Paragon Vision Sciences Clinical Study, April 2002.