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U.S. Department of Health and Human Services

Medical Devices

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Paragon Z CRT® (tisilfocon A) Rigid Gas Permeable Contact Lenses for Corneal Refractive Therapy - P050031

This is a brief overview of information related to FDA's approval to market this product. See the links below to the Summary of Safety and Effectiveness and product labeling for more complete information on this product, its indications for use, and the basis for FDA's approval.


Product Name: Paragon Z CRT® (tisilfocon A) Rigid Gas Permeable Contact Lenses for Corneal Refractive Therapy

PMA Applicant: Paragon Vision Sciences
Address: 947 East Impala Ave. , Mesa, AZ 85204-6619
Approval Date: November 16, 2006
Approval Letter: http://www.accessdata.fda.gov/cdrh_docs/pdf5/p050031a.pdf

What is it?

The Paragon Z CRT® contact lenses are rigid gas permeable contact lenses used for corneal refractive therapy, a process that temporarily corrects nearsightedness (myopia). The patient wears the lenses overnight while sleeping and removes them upon wakening. During the day, nearsightedness is corrected or greatly reduced.

How does it work?

The Paragon Z CRT® contact lenses apply slight pressure to the center of the cornea, causing it to temporarily flatten. The flattened cornea redirects light onto the back surface of the eye (the retina) at an angle that can compensate for nearsightedness. Since the cornea is elastic, it gradually regains its shape throughout the day (causing nearsightedness to return). Usually, patients must wear the lens every night to maintain corrected vision.

When is it used? The lenses are used for the temporary correction of nearsightedness. They can be used by patients with or without vision distortion (astigmatism). They are usually worn overnight as part of a corneal refractive therapy program. When the lenses are removed each morning, they must be cleaned using a chemical disinfection system.

What will it accomplish? When worn overnight, the lenses temporarily correct or reduce nearsightedness. This may allow the user to forgo glasses or contact lenses during the day.

When should it not be used? The lenses should not be worn by people who have any of the following:

  • Inflammation or infection of the eye
  • Disease or injury in or around the eye or eyelids
  • Severe insufficiency of tears (dry eyes)
  • Any other medical condition that might interfere with contact lens wear
  • Reduced corneal sensitivity
  • Allergic reactions that may be induced or exaggerated by contact lens or lens care solutions
  • Red or irritated eyes

Additional information: Summary of Safety and Effectiveness and labeling are available at: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cftopic/pma/pma.cfm?num=p050031