ORTHOKERATOLOGY

Orthokeratology (Ortho-K) is the use of rigid gas-permeable contact lenses, normally worn only at night, to improve vision through the reshaping of the cornea. This method can be used as an alternative to eyeglasses, refractive surgery, or for those desiring to not wear contact lenses during the day.

It is presumed that the lenses used in orthokeratology reshape the cornea by moving the epithelial cells that cover the surface of the cornea. Some studies indicate that the epithelial cells are compressed in some areas as well as relocated.

In the United Kingdom, the treatment is currently offered for corrections from +3.00 to -6.00D, with possible treatment up to -8.50D. Some patients may not be suitable for treatment. The US FDA approvals are for procedures up to -6.00D. Some patients with higher degrees of myopia are successfully treated by specialty practitioners with "off-label" uses of these same lenses.

Orthokeratology lenses are made by several companies, using one of two FDA approved technologies. All use special gas permeable lenses to reshape the cornea. The lens material is important for maintaining eye-health during the treatment.

Paragon Vision Sciences manufactures a lens trademarked the CRT (Corneal Refractive Therapy) and marketed as "Accelerated Orthokeratology" (AOK). Bausch & Lomb's "Vision Shaping Treatment" offers the choice of four approved designs that may only be fit by certified practitioners. The four designs in the VST portfolio include (alphabetically) "BE Retainer" backed by BE Enterprises Inc, "Contex OK-E System" backed by Contex Inc., "DreamLens" backed by Dreimlens Inc, "Emerald" backed by Euclid Systems Corp, and "Fargo" backed by C&E GP Specialists.

Only a few other brands of ortho-k lenses have been approved by the FDA for overnight wear. Currently no other studies are underway for any other lens designs.

In the United States, the initial cost of orthokeratology for both eyes typically varies from $800 to $2,500, however, there are generally additional fitting fees and lens costs from year-to-year. In the United Kingdom, costs are typically from £600 upwards, this would include aftercare for a year. The procedure was being promoted in September 2005 at £100 for an initial fitting and £40 per month for aftercare.

Orthokeratology has occasionally been associated with severe, even blinding complications. These often occur due to failure to follow appropriate hygiene, but may also be due to relative corneal hypoxia (lack of oxygen) with prolonged or overnight contact lens wear.