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Home » Contact Lenses » Orthokeratology (CRT & VST)

Orthokeratology (CRT & VST)

Pretty, young Ortho K Lenses brunetteIn 1994 the FDA granted the first ever daily wear approval for a lens indicated for Orthokeratology to a type of lens called the Contex OK-Lens. A significant milestone for the United States market occurred in June 2002 when the FDA granted approval for overnight wear of a type of corneal reshaping called “Corneal Refractive Therapy” (CRT). This forms the basis of the “Paragon CRT” product backed by Paragon Vision Sciences Inc. Subsequently in 2004, the U.S. Food and Drug Administration (FDA) approved a design from Euclid Systems Corporation (“Emerald”). Each FDA approval has a Premarket approval (PMA) number. The PMA number of the FDA approval for Paragon CRT is P870024; the PMA number of the FDA approval for Emerald is P010062.

Ortho-K (orthokeratology) is a nonsurgical eye treatment using specially designed contact lenses to gently reshape the curvature of the eye while you sleep to improve vision. Ortho-K retainer contact lenses are made of highly oxygen permeable material allowing for safe wear while you sleep. Ortho-K corneal refractive therapy lenses only affect the cornea of the eye. The cornea shape is critical in maintaining a sharp optical focus on objects by bending the light that enters the eye. The cornea is the clear part of the eye that covers the iris and the pupil. The corneal tissue is soft and can be subtly molded. The Ortho-k lenses float on your eye tear film, yet provide enough pressure reshape the cornea. The iSee™ Ortho-K therapy lenses gently reshape the first few microns of the cornea while you sleep.

Once the lenses are removed in the morning, the slight change in the curvature of the corneal surface results in clear vision during waking hours, thus reducing the need of daytime contact lenses or glasses. With iSee™ Ortho-K corneal refractive therapy contact lenses, 20/20 vision can be restored in as little as one day to a few weeks. The best part is that iSee™ cornea refractive therapy is safe, non-surgical, non-invasive and reversible.

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 Orthokeratology

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

Some consider Ortho-K to be a non-surgical alternative to LASIK. Nonetheless, 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.