How Ortho-k Works

Many people wish they could eliminate their need for contacts or glasses.   LASIK or other types or refractive surgeries are some of the most popular options fro permanent correction of one’s vision.  However, many do not feel safe taking the LASIK plunge.  Fortunately, there is another option, known as orthokeratology, often called ortho k.

Ortho k is a procedure that often works well for individuals with myopia (nearsightedness) as well as those with small amounts of astigmatism.  The procedure is performed using a special gas permeable contact lens that is worn at night to reshape the cornea, lessening the myopia.    Since myopia is generally caused by corneas that are too steep, the Ortho k lenses work to compress the cornea and flatten it in order to compensate for one’s nearsightedness.

Ortho k has been used practically as long as gas permeable lenses have been used.  Eye doctors that specialize in contact lenses have experimented with reshaping the cornea off-label for many years.

FDA Approved Ortho-k Procedures

In 2002, the FDA approved Paragon Vision Sciences’ procedures for reshaping corneas overnight using CRT (Corneal Refractive Therapy).  Currently, Paragon offers the system of Ortho-k that is most popular.

Bausch & Lomb also has an approved Ortho-k system known as Vision Shaping Treatment (VST).  While other companies offer Ortho K products, they are not approved by the FDA.

In order to fit each brand of lenses, doctors must complete a training and certification program that differs by brand of lens.

Who Can Use Ortho-k Lenses?

The degree of myopia approved by the FDA differs for the procedures approved by Paragon and Bausch & Lomb as well as what the doctors routinely treat.  The FDA guidelines are as follows:

Paragon CRT:

  • Up to -1.75 D of astigmatism
  • Up to -6.00 D (diopters) of myopia  


B & L VST:

  • Up to -1.50 D of astigmatism
  • Up to -5.00 D of myopia


Most eye doctors consider patients to be decent candidates with -4.00 D myopia or less along with little or no astigmatism (-0.25 to -0.50 D).  Of the two problems, Astigmatism offers a less predictable outcome than myopia after Ortho k.

Corneal reshaping is approved for people of all ages, including children.  The procedure is popular for individuals who are active as well as those participating in sports.  Teens are not considered for LASIK so CRT offers a good option for those active in sports such as football.

How Long Does Vision Correction Take?

With most patients, results are seen within two to three weeks after starting to wear the lenses.  The higher the prescription and presences of astigmatism requires more time.  Vision often fluctuated initially.  In addition, as the cornea begins to assume the new shape, there could be side effects including halos and glare.  Once the lenses have been used regularly for some time, the effect should last longer.  Under ideal conditions, correction should last all day until lenses are inserted again.

When patients discontinue use of the lenses, the cornea returns to its original shape within a few days.

Long-term Ortho k patients are often able to go longer than a day, sometimes up to a week without having to use the lenses.

Amount of Improvement Seen

Doctors usually limit the use of these lenses to patients likely to achieve 20/20 vision with the procedure.  The minimum to shoot for is 20/40, the legal limit for driving in most states.

According to the FDA study approving Paragon lenses 93% of patients achieved 20/32 or better vision and 67% achieved 20/20 or better.  In the study for VST designs, 95% of the patients achieved 20/40 vision or better while 73% achieved 20/20 vision or better.  Both studies tracked patients for 9 months or more.

Are Ortho-k Lenses Comfortable?

While gas permeable lenses were once more common, they are less popular as soft lenses are available for most patients.  Wearers may notice the lenses at first but less so as they adapt to the new sensation.

Adapting to gas permeable lenses often takes longer than soft lenses and it is important to follow the doctor’s directions.  Often, the patient is provided with a schedule increasing wear time each day. 

Since Ortho k lenses are mostly worn at night, sleeping with lenses in place helps to reduce the adaptation periods.

Ortho-k Cost

The cost of Ortho-k lenses is often determined by the time the doctor must spend in order to obtain a proper fit.  Sometimes it takes several lenses to find the appropriate set and lenses must be changed as the cornea changes shape.

Patients should expect costs to begin at $800, but they may range to $2000.  The cost will depend on prescription, type of practice and practitioner.

In most instances, Ortho-k is not paid by vision insurance.