May 3, 2002
New non-laser procedure treats farsightedness
Ann Arbor—People who are farsighted have a new option for correcting their vision. Physicians at the University of Michigan Kellogg Eye Center are offering a new non-laser technique, called Conductive Keratoplasty, (CK), to treat hyperopia or farsightedness, The procedure, which was recently approved by the FDA, uses the controlled release of low-level radiofrequency (RF) energy, instead of a laser, to reshape the cornea. It is performed in just a few minutes with only topical anesthetic in the form of eye drops. Kellogg is currently the only clinical practice in the state of Michigan that offers the procedure.
Hyperopia occurs when the cornea is too flat or the eye is too short so that light rays focus behind rather than directly on the retina. It affects more than 60 million people over age 40, affecting their ability to see fine print and other near objects.
Alan Sugar, M.D., corneal surgeon at Kellogg and professor of Ophthalmology and Visual Sciences, says that he views the procedure as a good alternative for some patients—those over the age of 40 with mild to moderate hyperopia. Dr. Sugar, who participated in the clinical trials, observes, "Most patients in the trials reported normal or near normal vision after the CK procedure. We also found that the healing time is faster than hyperopia laser procedures because CK does not involve cutting or removing corneal tissue."
CK is performed using a small probe, thinner than a strand of human hair, that releases low-level RF energy in a circular pattern on the outer cornea, thus shrinking small areas of corneal tissue. The circular pattern acts like a belt tightening around the cornea to increase its overall curvature.
A report on the clinical trial, in the April issue of the academic journal Ophthalmology, says that CK is safe and effective for correcting low to moderate hyperopia. The report also says that acuity, predictability and stability of sight are better than or as good as that achieved by two other procedures for farsightedness: LASIK (Laser Assisted in-situ Keratomileusis) and LTK (non-contact laser thermal keratoplasty). The paper, which documents the one-year results on the first 54 eyes—out of more than 400 treated with CK in the FDA study—reports that 57 percent of the eyes attained uncorrected visual acuity of 20/20 or better, and 93 percent attained 20/40 or better.
Until the advent of CK, Dr. Sugar and his colleagues at Kellogg performed vision correction surgery only for people with myopia or nearsightedness. The most common procedure is LASIK, a laser vision correction procedure that involves creating a flap in the cornea, treating the exposed tissue with the laser, and then replacing the flap. A related procedure, LASEK (Laser Epithelial Keratomileusis), involves creating a flap only in the topmost layer of the cornea, the epithelium. Then, as with LASIK, the laser makes the refractive correction. Kellogg also performs a non-laser procedure for myopia, in which the surgeon makes a small incision and inserts corneal ring segments in the outer edges of the cornea. Once in place, the two crescent-shaped segments flatten the cornea so that light can properly focus on the retina.
Hyperopia vs. Presbyopia
Hyperopia, which many confuse with presbyopia, tends to occur around age 40 and results in the inability to focus on close objects. It is caused by the shape of the eye--either the cornea is too flat or the eyeball is too short to focus the light rays onto the retina properly.
CK is currently in FDA Phase III clinical trials to study the procedure’s effectiveness for treating presbyopia, which also affects near vision. Presbyopia occurs when the lens inside the eye loses flexibility, preventing the ability to focus accurately on near objects. It is a normal part of aging and affects people at different ages, but generally by the age of 51.
Criteria for CK
People who meet the following criteria could be candidates for CK:
• Age 40 and over
• No drastic changes in vision or eyeglass prescription within the past year
• No eye conditions such as glaucoma, severe dryness, keratoconus, herpes of the eye, aggressive keloid formation or corneal dystrophy
• No physical conditions such as diabetes, pregnancy or nursing, and vascular or autoimmune diseases
The University of Michigan W.K. Kellogg Eye Center is a nationally recognized vision care and research center. As part of the University of Michigan Health System, Kellogg provides medical and surgical eye care, including laser eye surgery; professional and public education; and pursues advanced research to save vision. Kellogg also serves as a regional referral resource, providing specialty vision care that may not be available in other communities.
If you are a potential patient with questions about the CK procedure, please call Kellogg's Refractive Surgery Service at 734-615-6914.
Contact: Betsy Nisbet, 734.647.5586, bsnisbet@umich.edu.
Terms
Cornea, the transparent part of the coat of the eyeball that covers the iris and pupil and admits light to the interior of the eye.
CK (Conductive KeratoplastySM)), a non-laser procedure for treating hyperopia. It involves the controlled release of low-level radiofrequency (RF) to reshape the cornea. The energy is applied in a circular pattern on the outer cornea, and acts like a belt tightening around the cornea to increase its overall curvature.
LASIK (Laser Assisted in-situ Keratomileusis) is a refractive procedure in which a laser is used to create a microscopic flap in the cornea. It then sculpts corneal tissue underneath so that the cornea will form a more effective shape. The flap is closed and heals shut.
LASEK (Laser Epithelial Keratomileusis) is a refractive procedure in which only the epithelium (the outermost layer of the cornea) is detached by using an alcohol solution that weakens the epithelium and allows it to fold back into a flap. Then, as with LASIK, the laser reshapes the cornea. After the tissue is reshaped, the flap is returned to its original position.
Hyperopia or farsightedness occurs when the cornea is too flat or the eye is too short so that light rays focus behind rather than directly on the retina.
Presbyopia occurs when the lens loses flexibility, preventing the ability to focus accurately on near objects. It is a normal part of aging and affects people at different ages, but generally by the age of 51.
Myopia or nearsightedness occurs when rays are focused in front of the retina, making it difficult to see faraway objects.
