Developments bring new promise for corneal reshaping

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New lens technologies now allow patients to literally correct their vision overnight, according to the AOA Contact Lens and Cornea Section. And the best may be yet to come.

Corneal reshaping is in the midst of a renaissance, according to S. Barry Eiden, O.D., chair of the American Optometric Association (AOA) Contact Lens and Cornea Section (CLCS). Long touted as a potential way to provide corrected vision without appliances or surgery, corneal reshaping is now beginning to live up to its promise, Dr. Eiden believes. New products and techniques have already made corneal reshaping more practical, more predictable, and faster. With the procedure, corrected vision “while you sleep” has literally become a reality for many patients, the manufacturers of corneal reshaping lenses note. And Dr. Eiden believes the best may well be yet to come. Ongoing research offers hope that in the not-too-distant future, corneal reshaping will help control the problem of progressive myopia, be used to correct virtually all common vision problems, and ultimately provide extended duration correction.

First introduced as orthokeratology (Ortho-K), corneal reshaping involves the therapeutic application of contact lenses to correct vision by altering the shape of the cornea. Traditionally, the procedure has involved the application of a series of standard rigid gas permeable (RGP) lenses with progressively flatter base curves to gradually flatten the cornea over a period of days or weeks, thereby correcting myopia. Once the desired correction is achieved, a retainer lens is used to maintain the correction. The technique was developed in the 1960s as contact lenses became widely available and practitioners began noticing that the lenses sometimes tended to change the shape of the eye, producing an unintended change in refraction. Noting that in such cases corneas tended to remain in their newly assumed shape for a period after the contact lenses were removed, contact lens practitioners quickly concluded that the lenses could be used to achieve a targeted reshaping, thereby correcting vision without lenses for at least a limited period. While that prospect has always had appeal, corneal reshaping has never really caught on with either vision care practitioners or the general public, Dr. Eiden acknowledges—and for a variety of reasons, he adds. Since its inception, corneal reshaping has been a relatively complex and time-consuming process involving the application of multiple lenses. It has generally been neither very predictable nor very long-lasting. Even after the desired correction was achieved, patients have essentially had to wear contacts part of the day to achieve freedom from lenses during the rest of the day. That was largely because over most of the last 30 years, most rigid gas-permeable lenses have not had oxygen permeability sufficient to allow wear overnight. However, in the late 1990s, contact lens makers began to develop new lenses that would solve most of those problems, revolutionizing the field of corneal reshaping. In 2002, the U.S. Food and Drug Administration (FDA) approved Paragon Optical's Corneal Refractive Therapy (CRT) lens. Bausch & Lomb's Vision Shaping Treatment VST® was approved not long after.

The new corneal-shaping contact lenses have 2 distinguishing features that set them apart from traditional Ortho-K lenses:


•High oxygen permeability, which allows them to be worn during sleep


•“Reverse geometry” design—a flat center, surrounded by a steep “reverse” curve, and then alignment and peripheral curves for fitting purpose—providing predictable corneal shape changes within very short periods of time (see Figure 1, Figure 2)

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• Figure 1 

  Drawing of Paragon contact lens shows the reverse geometry design now being used for corneal reshaping.

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• Figure 2 

  Fluorescein photo shows structure of the reverse geometry lenses used in the Bausch & Lomb Vision Shaping Treatment.




Together the 2 lens features have increased the accuracy and stability of correction while greatly reducing the total time necessary for the procedure. The result has become known as overnight corneal reshaping, Dr. Eiden notes. Because the highly oxygen-transmissible lenses can be worn overnight, the need for any daytime wear is eliminated. Wearers correct their vision overnight while they sleep. At least some correction is often seen after the first night's use, Dr. Eiden said. Targeted correction is achieved in anywhere from 1 to 2 days to 1 to 2 weeks, depending on the patient, Dr. Eiden reports. The total time required for the procedures depends on the degree of correction desired and the biomechanical properties of the eye. Up to 5 diopters (D) of myopia can be corrected with either of the available lenses. (The Paragon lenses are actually approved for correction of up to 6 D). In addition to myopia, both lenses are also approved for correction of mild astigmatism (up to –1.50 D cylinder). As in the past, once the desired correction is achieved, patients must continue to wear the lenses periodically to maintain the correction. However, the new lens advancements allow the retainer lens to be worn at night when it may be more convenient. At least one of the lenses is approved by the FDA for use without restriction on age. The youngest corneal reshaping patient in Dr. Eiden's practice so far was 8; the oldest was 63.

Most of the corneal reshaping patients in Dr. Eiden's practice are children and young adults. Lens makers are marketing the procedures largely to those with active lifestyles (firefighters, military, police, athletes, outdoorsmen) who desire “device-free” correction. However, many corneal reshaping patients opt for the procedure because they fear possible complications associated with refractive surgery. Unlike refractive surgery, corneal reshaping is easily reversible, Dr. Eiden notes.

Dr. Eiden believes that, over the long term, corneal shaping will be of greatest benefit to younger patients who may be at risk of progressive myopia. The incidence of progressive myopia is increasing around the world, particularly among Asian populations. The condition can significantly impact patients' lifestyles and is associated with other health conditions, Dr. Eiden said. The apparent effectiveness of corneal reshaping in treating the condition could have significant implications, according to Dr. Eiden. At least 2 studies have found that corneal reshaping slows the rate of progression in such patients. The Longitudinal Orthokeratology Research in Children (LORIC) study conducted in Asia found a markedly slower rate of progression among young progressive myopia patients who underwent corneal reshaping than among those who wore eyeglasses. The Corneal Reshaping and Yearly Observation of Nearsightedness (CRAYON) study, conducted by researchers at The Ohio State University College of Optometry, also found lower rates of progression among corneal reshaping patients compared with patients who wore contact lenses. Both the LORIC and CRAYON studies were relatively small in scale, each involving fewer than 40 patients. However, Dr. Eiden is among the lead researchers for the Stabilization of Myopia by Accelerated Reshaping Technique (SMART) study, a large-scale (300 patient), 5-year, longitudinal, multicenter evaluation of the effectiveness of corneal reshaping for progressive myopia patients, which is now under way. First-year results are encouraging, he reports.

Corneal reshaping lenses for the correction of higher-level myopia, higher-level astigmatism, and hyperopia are under development and could be released within the next few years, Dr. Eiden reports. Particularly encouraging are results indicating that corneal reshaping is effective in controlling change in axial length. Axial length is a key underlying component of myopia, he notes. Work is under way on the development of pharmaceuticals to “fix” refractive changes for prolonged periods, potentially allowing corneal reshaping patients to go without wearing retainer lenses for weeks or more. Several such pharmaceuticals are under development.

Corneal reshaping has its “nay sayers” within eye care, Dr. Eiden admits. They generally fall into 2 categories: those who do not believe that corneal reshaping actually works (although Dr. Eiden believes peer-reviewed studies now provide evidence of efficacy) and those who feel the procedure poses increased risk for corneal infections that will offset its benefits. (FDA clinical trials on the new corneal reshaping lenses did not find a statistically significant increase in microbial keratitis among corneal reshaping patients. However, although corneal infection should be considered a risk particularly among younger patients, Dr. Eiden said, such patients must be counseled on keeping lenses clean.)

Even with the recent improvements, and its inherent appeal for those who seek freedom from eyewear or dislike the risks of surgery, corneal reshaping is still not achieving great market acceptance, Dr. Eiden acknowledges. That is largely because it has received relatively little publicity, and few people know about it, he says. Relatively few eye care practitioners provide the service, he adds. In addition, many contact lens wearers may not yet see a substantial advantage. “They may reason, ‘I put my contact lenses on the morning and take them out at night; with (corneal reshaping) I put them in at night and take them out in the morning. What's the difference?’” Dr. Eiden acknowledged.

Dr. Eiden suspects that real market acceptance will only come after pharmaceutical fixes are available and if myopia stabilization is definitively supported by research findings. However, now may be a good time for practitioners to start offering corneal reshaping and educating their communities on the procedure. Both Bausch & Lomb and Paragon offer certification programs in corneal reshaping. Both also offer promotional materials to certified practitioners.