- Non-Invasive Eye Surgery for
- Hyperopia and Presbyopia
Conductive keratoplasty (CK) is a relatively new type of refractive surgery that uses mild heat from radio waves to shrink the glue-like connective tissue (collagen) in the periphery of the cornea.
This steepens the cornea, giving farsighted patients with presbyopia better near and distance vision while improving near vision for patients with presbyopia alone.
If you are nearsighted, CK is not for you, although expanded indications such as for astigmatism correction are being studied.
Better surgical techniques and technology now address earlier problems with CK in that some corneas tended to revert to original states and vision corrections failed to remain stable (regression). With recent clinical studies revealing more stable results, CK is gaining wider acceptance among eye surgeons and patients.
Long-term data ultimately will determine whether CK’s results will be comparable to other vision correction procedures such as LASIK.
CK technology exclusively belongs to Refractec Inc. (Irvine, Calif.), which markets the system under the trade name of Refractec ViewPoint CK. The Wall Street Journal estimates costs of CK vision correction per eye to be between $1,500 and $2,000, and a physician investment in the system to be about $50,000.
A similar technology known as laser thermal keratoplasty (LTK), on the other hand, appears to have faded away. The Hyperion LTK system had been sold by Sunrise Technologies International Inc., Menlo Park, Calif., which filed for bankruptcy in 2002 after initially receiving FDA approval to market the LTK system in 2000 for temporary reduction of hyperopia. The FDA approval also noted the tendency for patients treated with LTK to experience regression.
LTK used laser-based technology to achieve shrinkage of collagen, whereas CK uses radio waves applied at deeper levels within the cornea to achieve more lasting thermal effects. The main advantage of CK is that it is non-invasive. Unlike LASIK, CK does not involve knives or lasers cutting into ocular tissue, nor is any instrument inserted into the eye. Therefore, CK tends to cause fewer surgical complications than other refractive procedures.
CK, the Radio Waves Eye Surgery
Conductive keratoplasty received FDA approval in April 2002 for people 40 or older with mild farsightedness. In 2004, expanded FDA approval included presbyopia, a condition that develops beginning about middle age in which your eye’s natural (crystalline) lens stiffens and can no longer focus at near, middle, and distant ranges at the same time. CK correction for presbyopia differs from hyperopia in that only one eye (the non-dominant eye) is corrected for near vision, while the other eye is left untreated.
After someone with presbyopia receives CK, the treated eye is able to see at near ranges, while the untreated eye sees at middle to distant ranges.
Candidates for this type of vision correction, known as monovision, may be asked first to wear contact lenses for near vision correction to make sure they are able to adapt. But this is not a requirement. The eye surgeon instead might hold a +1.00 lens for near vision correction in front of the non-dominant eye to see if the person experiences significant distance blur at a distance with both eyes open. People who do not have blurry distance vision under these circumstances likely are very good candidates for CK.
CK offers a major advantage in that the procedure is less likely to blur distance vision with monovision correction than contact lenses or laser vision correction.
CK uses heat from radio frequency waves to shrink collagen and change the shape of the cornea. The surgeon uses a hand-piece containing a tiny, pen-shaped probe (Keratoplast Tip) that releases the frequency over the periphery of the cornea. The procedure takes about 15 minutes.
To qualify for CK correction of hyperopia, you must be 40 or older and have between +0.75 and +3.25 diopters of refractive error, with no more than 0.75 diopters of astigmatism. Also, your glasses or contact lens prescription cannot have changed within one year before the surgery.
To make sure CK correction of presbyopia is right for you, your eye surgeon may test you with a trial period of wearing monovision contact lenses in which one eye is corrected for near vision and the other eye is corrected for far vision. Or, the surgeon may determine if you are a good candidate for monovision correction by holding a test lens in front of your non-dominant eye to make sure your distance vision remains sharp. [Read more about monovision with contact lenses.]
CK treatment parameters for presbyopia allow induction of myopia in the eye being corrected for near vision between a range of -1.00 to -2.00 diopters. As with hyperopia correction, your glasses or contact lens prescription cannot have changed within one year before the surgery.
Note also that FDA approvals indicate that CK corrections at this time are temporary, although recent improvements in surgical technique appear to be stabilizing outcomes.