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What are Ortho-k Lenses?

Paragon CRT® Contact Lenses, approved by the FDA in June 2002, are therapeutic contact lenses that gently reshape the cornea while you sleep to correct nearsightedness. Referred to as “Orthokeratology,” Paragon CRT® Contact Lenses is a non-surgical and non-invasive procedure that temporarily corrects nearsightedness up to -6.00 diopters, and mild amounts of astigmatism.1


How Do Paragon CRT® Contact Lenses Work?

Nearsightedness occurs when the eye lengthens, causing the light entering the eye to focus in front of the retina rather than directly onto it, making distant objects blurry. When worn overnight, Paragon CRT® Contact Lenses gently flatten the front surface of the cornea, resulting in a corneal shape that focuses light correctly onto the retina. When removed in the morning, distant objects will be back into focus.

The goal is to correct your vision without wearing eyeglasses or contact lenses during the day. In the FDA trials for Paragon CRT® Contact Lenses, more than 65% of patients were able to achieve 20/20 vision after wearing the reshaping lenses overnight and more than 90% were able to see 20/40 or better (the legal vision requirement for driving without glasses in most states).1

Benefits of Paragon CRT® Contact Lenses

Wearing Paragon CRT® Contact Lenses while sleeping gives you freedom from wearing daytime contacts or glasses. No more dry, itchy and uncomfortable contact lenses. No hassles and interference of wearing glasses either – just great vision. You, or your child, no longer have to worry about torn lenses, broken frames or contact lens-induced dry eye. Your teen will have confidence knowing they look their best and have great vision throughout school and activities.

Research and Clinical Studies

Doctors discovered the reshaping phenomena of glass lenses in the 1940s, which instigated research in orthokeratology and the use of contact lenses for myopia reduction. This led to early lens designs in the 1960s that had generally unpredictable results, compelling researchers to believe that applied orthokeratology was more art than science.

However, when computerized corneal topography became available during the 1990s, it became possible to create designs with repeatable results. Additionally, the development of new base materials for rigid gas permeable lenses allowed orthokeratology to become an overnight procedure rather than for daytime wear only. Finally, the introduction of computer-controlled precision lathes meant that lens designs could be manufactured to sub-micrometer levels of accuracy. In June 2002, the FDA granted approval for overnight wear of a type of corneal reshaping called “Corneal Refractive Therapy” (CRT).

Read more about CRT research and recent clinical studies on this amazing therapy.


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  1. Paragon Vision Sciences Clinical Study, April 2002.