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A Brief History of OrthoKeratology

OrthoKeratology (also known as OrthoK and Corneal Refractive Therapy – CRT) has a 50 year history of correcting myopia in children. In the early days of contact lenses, doctors noticed that their patients wearing hard contact lenses would report less blurry eyesight, seeing better at distance after removing the contacts than they did before they put them in. They also noticed that some patients in these hard lenses vision changed less than people in just glasses. They discovered the reason for this was that the lenses that had these effects fit flatter on the curvature of the eye than standard contact lenses, exerting a gentle pushing effect which temporarily reduced the amount of nearsightedness for the wearers.The practice of prescribing these “flatter” lenses went on for many years, until a company filed a special design and healthier contact lens plastic for approval by the FDA. The FDA approved accelerated orthok in the late 1990′s for children of all ages. The procedure involves the child putting an orthokeratology lenses (ortho k lenses) in their eye before bed – when the eyes are closed they don’t feel the lenses; while they sleep they undergo gentle corneal reshaping which results in corneal refractive therapy. Upon awakening when they remove the lens they see perfectly clear all day until bedtime, when they need to reinsert the lens. There is no age restriction on orthokeratology.

Corneal reshaping therapy options such as OrthoK, cornea refractive therapy including paragon crt (vision shaping treatment) are particularly helpful when seeking to improve eyesight in children with nearsightedness and astigmatism, and reduce change in vision , specifically myopia in children and may, in some cases reduce the risk of children with myopia advancing to high myopia. If you are interested in managing your vision or the vision of a loved one with nearsightedness and concerned about vision changes, please contact our office at (703) 680-4323.

Corneal Reshaping through Orthokeratology (OrthoK)

The curve of the cornea (front surface of the eye) is largely responsible for refractive errors such as nearsightedness (myopia), farsightedness (hyperopia) and Astigmatism, the culprits behind blurry eyesight. For nearsightedness (myopia), the cornea may be steeper than average, causing light to enter the eye producing a blurry image for the retina. For farsightedness (hyperopia), the cornea may be flatter than average, which, depending on the age of the individual, creates problems focusing at different ranges of vision (near vs far). Astigmatism is when the cornea is steeper in one meridian yet flatter in another, causing images that enter the eye to be distorted to some degree.Corneal reshaping, either surgically (LASIK, PRK or Orthokeratology) can minimize or eliminate the refractive error caused by a cornea that is too flat, too steep or astigmatic. These methods seek to flatten the curve of the cornea in nearsighted (myopic) individuals surgically or non-surgically with orthokeratology lenses (ortho k lenses) in a process commonly known as corneal reshaping, cornea refractive therapy (Paragon CRT) , corneal reshaping therapy and Vision shaping treatment (VST).


Contact lenses were mainstreamed in the early 1960s with the introduction of Polymethylmethacrylate (PMMA) lenses to the market. These lenses are known historically as “hard” lenses. At the time PMMA lenses were introduced to the market, the only corrective option for millions of people was eyeglasses. A few years after the introduction of PMMA contact lenses, patients were reporting some interesting experiences; some noted that they could see for a period after they removed their contacts without the aid of glasses. They might wear their contacts all day and remove them to go to a cocktail party or such. Doctors noted that in some cases progressive myopia slowed down in people who had repeatedly year after year manifested increases in prescription. Doctors discovered that lenses that were fit flatter than the curvature of the cornea were the reason for both phenomena, so they started purposefully fitting the contact lenses flatter. The results were dramatic in some cases. People with generally less than a certain amount of prescription could remove lenses and see, sometimes for an entire day. The resulting therapy took on the name orthokeratology, or orthoK for short. “Ortho” is latin for straight and “keratology” is the science of altering the shape of the cornea. While interesting and helpful for many patients, PMMA material is not permeable to oxygen, so there were some inherent risks in extending wear of these lenses to achieve the desired effect. Also, fitting them to achieve the desired effect was an arduous and inexact science.

In the 1970s plastics for contact lenses were developed that had a higher permeability to oxygen. The flourosilicon elastomers proved safer and healthier for the eye and reduced the risks of orthokeratology, but fitting these lenses was still challenging for doctor and time consuming for patients.

In the 1990s plastics were developed that reached a new level of oxygen permeability. These “hyper-permeable” lenses made sleeping in gas permeable contacts much safer. In the late 1990s, a company also developed a lens shape, known as “reverse geometry” that greatly increased the ease of fitting and success for orthokeratology patients. Combining the healthier materials with the reverse geometry dimensions, orthokeratology became much more popular and was mainstreamed. It provides excellent vision sans glasses or contacts for thousands of people worldwide. Studies have been performed that demonstrate the safety and efficacy of the procedure, and other studies have been performed that demonstrate that orthokeratology is successful at managing myopic shift, providing the only known way of providing myopia control for contact lens wearers. Orthokeratology is not without risks, but the risks of orthokeratology are very similar to the risks one has wearing any contact lenses, specifically extended wear contact lenses (lenses people sleep in). This includes an infection of the cornea known as a keratitis, which is treatable if diagnosed promptly.

Options such as Orthokeratology ( OrthoK) cornea refractive therapy including paragon crt vision shaping treatment) are particularly helpful when seeking to improve eyesight in children, and reduce change in vision , specifically myopia in children and may, in some cases reduce the risk of children with myopia advancing to high myopia. If you are interested in managing your vision or the vision of a loved one with nearsightedness and concerned about vision changes.

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