Conductive keratoplasty (CK) is a treatment used for mild and moderate farsightedness (hyperopia) and presbyopia, a form of farsightedness known as "aging eye," in which the eye gradually loses its ability to focus on close-up objects or print. CK is a non-laser technique that uses mild heat energy to reshape the cornea for better vision.
What Is Conductive Keratoplasty?
As is the case with other types of refractive surgery such as LASIK, conductive keratoplasty is designed to correct and change the way that light enters the eye. CK is designed to correct farsightedness, which occurs when the eyeball is not quite long enough to focus light optimally on the inside back surface of the eye, or when the cornea (the clear fluid part that covers the eye) is too flat to focus the light the right way for clear vision.
In CK, a probe with a very fine needle tip is touched directly to the cornea. Radio waves are transmitted through the probe, applying heat to a small area (no incision is made in a CK procedure, and no tissue is removed). The probe is applied in a pattern of spots around the mid-cornea or its periphery, and when the spots heal, they shrink up and gently tighten like a belt around the cornea, making the curvature of the central cornea steeper. The pattern, number, and location of treatment spots are very precisely calibrated to obtain the best new shape of the cornea for optimum vision.
A CK procedure involves little or no pain, or even discomfort. Anesthetic eyedrops can be used for comfort. The vision improvement that CK provides is almost instantaneous. However, the effect of CK treatment may be temporary, and additional treatment may be necessary at a later date.
Although farsightedness is often associated with older people wearing reading glasses or holding a newspaper at arm's length to be able to read the small print, young people can also be farsighted. Hyperopia is the term for this farsightedness. Many people don't notice that they're farsighted until they reach their 20s or 30s, because before that time, their eyes' lenses were able to correct for the problem. With age, a lens continues to lose flexibility and loses the ability to focus on close-up objects. Hyperopia is quite common, estimated to affect about 62 percent of people over the age of 40.
As people reach their 40s, the lens inside the eye can start to lose a significant amount of its elasticity, becoming less able to focus on near objects. This age-related loss of near vision is called presbyopia, and is a natural result of aging. Presbyopia is not the same as hyperopia, but it is also very common among people over 40. It's estimated that in the United States alone, there are 90 million "baby boomers" who either have presbyopia now or will develop it within the next 10 years. CK is used to treat both hyperopia and presbyopia.
Who Is a Good Candidate to Undergo CK?
A good candidate to undergo conductive keratoplasty is at least 18 years old and has:
- Eyes free of disease
- A vision prescription that has been stable for at least a year
- Vision within the correctable range for CK
CK is most often used for people who are over 40 years old and have trouble seeing objects and print that are near (less than two feet away). The best CK candidates are over 45 years old and have good far/distance vision without glasses or contacts.
On the other hand, you might not be an appropriate candidate for CK if you:
- Have had an autoimmune disease
- Are pregnant or nursing
- Have had an eye disease or an eye injury
- Take prescription medication that might affect the healing of your cornea or your vision
In addition, if you are nearsighted when you develop presbyopia, it's generally thought that LASIK may be a better option for you than CK. Discuss your vision history and concerns at length with an ophthalmologist who is experienced with both the CK and LASIK procedures to decide which procedure is right for you.
The CK procedure typically costs about $800 to $1,500 per eye.
CK Risks and Benefits
Conductive keratoplasty has allowed many people to lessen or eliminate their dependency on glasses or reading aids. The CK procedure itself, conducted after extensive testing and measurement of the eye(s), takes only a few minutes at a physician's office, and usually provides nearly instantaneous vision improvement. It's non-invasive, requires no cutting or removal of tissue, and is very safe.
Side effects and complications of CK are very rare. However, CK is a refractive surgery, and as with any refractive procedure, potential side effects do exist. These include:
- Visual problems such as seeing starbursts or halos around lights at nighttime, hazy vision, double vision
- Sensitivity to light
- Under- or over-correction
- Anisometropia: a difference in the focusing ability of one eye compared to the other
- Dry eye
- Eye irritation after the procedure
- Allergic reaction to the anesthetic eyedrops
Each of these side effects can be temporary, and steps can be taken to eliminate or lessen them.
The procedure for conductive keratoplasty was first approved by the U.S. Food and Drug Administration (FDA) as a treatment for farsightedness (hyperopia) in 2002. In 2004 the FDA approved CK as a treatment for presbyopia. More than 100,000 CK procedures have been performed since the 2002 approval, and CK is now the fastest-growing refractive surgery since LASIK was introduced.
Extensive clinical studies of CK were conducted before the procedure was approved by the FDA, and the effectiveness and safety of CK were confirmed in those studies. However, because CK is a relatively new procedure, no long-term study results have been obtained. In addition, the results of CK can be likened to a facelift; as a patient's natural aging process continues to affect the face or eyes, the procedure's effects will be overcome and further treatment may be desirable. The eyes' lenses will continue to lose their flexibility, and five to 10 years after the initial CK procedure, an individual may find that he or she again needs presbyopia correction in some form.
Alternatives to CK
Many people choose to simply keep using reading glasses rather than undergo any type of treatment for their presbyopia. As mentioned above, aging will continue to lessen the ability of most people's eyes to focus on both far and near objects. For those individuals who would prefer to reduce their dependency on reading glasses and for whom CK is not an option, a number of alternatives exist. Please consult your ophthalmologist for more information about these options.
The most common alternative to refractive surgery for presbyopia is glasses that have bifocal lenses. Bifocals provide two prescriptions in one set of lenses: one for nearsightedness or farsightedness, and one stronger prescription for seeing close-up print or objects.
Progressive Addition Lenses (PALs)
A more recent development is eyeglasses with progressive addition lenses (PALs) that provide a smooth, unlined transition from near vision to intermediate vision to distance vision. Glasses with PALs have become quite popular, as they eliminate the use of bifocals or "granny glasses" for reading.
Bifocal Contact Lenses
Contact lenses for presbyopes, called multifocal or bifocal contact lenses, are another option. They're available in both permanent and disposable forms. Bifocal silicone hydrogel contact lenses were also introduced to the market in February 2006.
Monovision obtained with contact lenses is another alternative to CK. One eye uses a contact lens with a distance prescription, and the other eye uses a contact lens with a near-vision prescription. This works very well for some people, but can cause dizziness and/or other vision problems.
All of these alternatives to CK have both merits and drawbacks. Your vision is unique and precious — find an ophthalmologist with DocShop to determine what treatment or vision aid is right for you.
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