Thermal keratoplasty for farsightedness
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Thermal keratoplasty for farsightedness
Thermal keratoplasty is a type of refractive surgery that uses heat to change the shape of the cornea by shrinking the collagen fibers in the cornea. Though the treatment is not effective for severe farsightedness (hyperopia), it has been shown to be effective in correcting mild to moderate farsightedness. Thermal keratoplasty can be applied through a laser (noncontact) or probes (contact).
Noncontact technique
Laser thermokeratoplasty (LTK) involves applying pulses of laser light in ring formation to the cornea, which heats the collagen and changes the shape of the cornea. Actual treatment time is only a few seconds per eye.
LTK has been approved for people over 40 years of age who have hyperopia of 2.5 diopters or less. Trials of the procedure by the U.S. Food and Drug Administration (FDA) showed that about 80% of eyes were corrected to within 0.50 diopters of the desired result.1 A joint Canadian-Mexican study found that about 82% of eyes were corrected to within 0.50 diopters of the desired result at 2 years after surgery, but that some loss in near vision may occur, indicating that further study of long-term outcomes is needed.2 There is some discomfort, including expected initial overcorrection of vision, after the procedure.
Contact technique
Conductive keratoplasty is a relatively new technique, approved by the FDA in 2002, that can treat mild to moderate farsightedness of between 0.75 and 3.25 diopters. A contact probe delivers radiofrequency energy to multiple locations on the cornea, shrinking the collagen and steepening the central cornea. Treatment takes less than 1 minute per eye.
Disadvantages of the procedure include an initial overcorrection, inability to treat astigmatism, and a possibility of inducing astigmatism. Also, the correction may not last, so you may need to have the procedure again.
References
Citations
Sher NA (2001). Hyperopic refractive surgery. Current Opinion in Ophthalmology, 12(4): 304–308.
Rocha G, et al. (2003). Two-year follow-up of noncontact holmium laser thermokeratoplasty for the correction of low hyperopia. Canadian Journal of Ophthalmology, 38(5): 385–392.
Credits
| Author | Jeannette Curtis |
| Editor | Kathleen M. Ariss, MS |
| Associate Editor | Pat Truman, MATC |
| Primary Medical Reviewer | Kathleen Romito, MD - Family Medicine |
| Specialist Medical Reviewer | Christopher J. Rudnisky, MD, FRCSC - Ophthalmology |
| Last Updated | November 23, 2007 |
| Last updated: | November 23, 2007 |
|---|---|
| Author: | Jeannette Curtis |
| Reviewed By: | Kathleen Romito, MD - Family Medicine, Christopher J. Rudnisky, MD, FRCSC - Ophthalmology |
| Editors: | Kathleen M. Ariss, MS, Pat Truman, MATC |
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