Doctors discovered more than 100 years ago that placing a hot needle in the cornea of the eye would cause it to change shape, becoming steeper.
But that clue to improving the near vision of farsighted people was never put to much use -- until now. New techniques -- one recently approved by the Food and Drug Administration and another expected to be available to consumers next year -- could make vision correction surgery a popular option for farsighted people.
In farsightedness, or hyperopia, the eye's corneas are too flat. In childhood and early adulthood, the eye is usually still able to focus despite the defect. But, as the person ages, the focusing range decreases. This usually leads to blurred near vision after age 40 and, eventually, poor distance vision too. (This is different from presbyopia, which involves the decline of near vision only after age 40 or so.)
Unlike those with nearsightedness, or myopia, who have been flocking to laser vision centers (mostly for the Lasik procedure, in which the cornea is cut to altervision) over the past three years, there have been few satisfactory surgical options for farsightedness.
Lasik and other surgeries that involve cutting the cornea can be used for farsightedness to some degree, but they were created primarily for nearsightedness and carry some risks.
''Hyperops have been neglected,'' says Dr. Sandra Belmont, director of the Laser Vision Correction Center at Weill Cornell Medical Center in New York City. ''There was a big rush to treat myopia all these years. But there are more potential candidates for (a hyperopia) procedure than for myopic Lasik. Now we can say to hyperops that there is a specific technique designed for you.''
That technique is the Sunrise Hyperion Laser Thermal Keratoplasty, which was approved by the FDA last month for correcting mild to moderate farsightedness in people who don't have astigmatism (another type of vision distortion in which the curve of the cornea is unequal).
Another technology to correct farsightedness -- conductive keratoplasty, which uses radio waves to heat the cornea -- is in stage-three clinical trials and could become available to consumers as soon as next year.
Although there are some drawbacks to the new FDA-approved LTK procedure, it could help make surgery the preferred method for treating imperfect vision, experts suggest.
''We are gradually adding to our armamentarium,'' says Dr. Robert Maloney, director of the Maloney Vision Institute in Los Angeles. ''It is one more step closer to eliminating glasses and contacts.''
In LTK, a laser is used to heat and shrink collagen in the cornea and reshape it.
Not only is the procedure fast (about three seconds per eye), it is considered extremely safe. Unlike other vision correction surgeries, no tissue is cut or removed from the cornea. Instead, the periphery of the cornea is heated in various spots to shrink the collagen tissue and cause the steepening effect required for correction.
Although Lasik and other refractive surgeries that preceded it were designed to treat nearsightedness, LTK was always intended for farsightedness, says C. Russell Trenary III, the chief executive of Sunrise Technologies Inc., of Fremont, Calif., which received FDA approval to market its LTK device.
With Lasik, he says, ''You have the difficulty of adapting a technology designed to flatten the cornea.''
But the downside to LTK was made distinctly clear by the FDA in wording its approval. According to the government agency, the procedure is for the ''temporary correction'' of hyperopia.
Experts disagree on what ''temporary'' means in this case. But all acknowledge that many LTK patients will gradually lose some of their correction over time.
''We know that, between six months and two years, the amount of correction will be reduced by half in many people,'' says Dr. Everette Beers, acting chief of the FDA's diagnostic and surgical devices branch, adding that the LTK approval was based on only two years of data.
Unlike nearsightedness, in which refractive surgery is assumed to confer a fairly stable correction, the farsighted eye tends to keep changing over time.
''Refractive surgeries for hyperopia have been plagued by regression,'' says Dr. Jonathan Davidorf, a clinical instructor of ophthalmology at the University of California, Los Angeles' Jules Stein Eye Institute and director of the Davidorf Eye Group in Los Angeles. ''It even happens with Lasik, even though it appears to be more stable than the others.''
But, Davidorf notes: ''Regression doesn't mean it goes back to exactly what it was.''
According to Sunrise's Trenary, long-term data on LTK correction (more than was presented to the FDA) show that most people could go three to five years with a satisfactory result -- some as long as 11 years. Most of the regression occurs within the first six months.
Eventually, says Trenary, ''patients who receive this procedure could want to go back to the doctor for a re-treatment or a change of glasses or contacts.''
However, there is no information on the success rates of repeated LTK treatments. Would repeat treatments last as long? And how many treatments can the eye tolerate?
''We don't have sufficient data on re-treatment after LTK,'' says the FDA's Beers. ''We say in the labeling that it is unproven.''
Trenary says the LTK equipment will be shipped to doctors this month, and that as many as 100 ophthalmologists will offer LTK within a year. But some practitioners may continue to prefer Lasik or may wait for developing technologies, such as conductive keratoplasty.
''LTK is very safe, and it's also very quick and easy for the doctor and the patient. But it doesn't allow us to do something we can't already do,'' says Maloney, who has not yet decided whether to offer LTK. ''With Lasik, we can correct farsightedness with astigmatism.''
But only about 10 percent of people undergoing Lasik are farsighted, a statistic that suggests these patients want better alternatives, says Dr. Brian S. Boxer Wachler, director of the UCLA Laser Refractive Center at the Jules Stein Eye Institute. Boxer Wachler, who participated in the LTK clinical trials, will soon become the first Southern California doctor to offer it.
''These are people who are not coming in (for refractive vision surgery) because they aren't that visually impaired,'' he says.
And because they can often get by with reading glasses, some farsighted people don't want to take a risk with more invasive surgery, such as Lasik, no matter how slight, Boxer Wachler suggests. Lasik has been associated with a small number of troublesome side effects, such as dry eyes, glare and reduced night vision. On very rare occasions, blindness has occurred due to the surgery. While the overall rate of side effects associated with Lasik is low (around 1 percent of cases), it may be slightly higher among farsighted people undergoing the procedure. ''Lasik still has the fear factor involved,'' says Belmont. ''LTK eliminates that. The patient just sits there and looks at the light, and it takes 2.8 seconds and it's done. This procedure has a big wow factor.''
Whether people are attracted to LTK may have more to do with whether they are willing to get re-treated every few years and whether surgeons will provide re-treatments free or at low cost. The initial LTK treatment is expected to cost about the same as Lasik -- $1,500 to $2,000 per eye.
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