Orthokeratology, or Ortho-K, is a procedure that uses RGP contact lenses to change the curvature of the cornea to improve its ability to refract light and successfully focus on objects. Unlike regular RGPs, Ortho-K RGPs have a design that can reshape the curvature of the cornea. This method, however, does not produce a permanent result.
With conventional Ortho-K, the lenses are worn about eight hours a day. After the cornea has achieved the best shape for optimal vision, the lenses are worn less frequently--perhaps for a few hours every two or three days. If someone starts and then discontinues Ortho-K, says Saviola, the corneas will eventually return to their natural state. People choose Ortho-K over refractive surgery because Ortho-K's effects are not permanent.
One disadvantage of Ortho-K is that clear vision may fluctuate during the day. Also, Ortho-K may take many months to change a person's vision. A more advanced technique known as "accelerated Ortho-K" takes less time, and may be recommended to achieve a rapid effect.
Since 1998, Saviola says the FDA has cleared a number of daily wear Ortho-K lenses, but overnight Ortho-K lenses have not been approved.
The best candidates for prescription Ortho-K are people of any age who have low amounts of nearsightedness or astigmatism. The goal is to bring the person's vision to at least 20/40. But for some, Ortho-K will provide 20/20 vision.
Corneal Ring Segments
In 1999, the FDA approved a non-laser surgical procedure for correcting small amounts of nearsightedness. Corneal ring segments are tiny, clear crescent-shaped pieces of plastic polymer that are implanted in the cornea. The ring segments reshape the cornea so that it becomes flatter, allowing it to focus light rays onto the retina and producing sharp vision. The procedure takes about 15 minutes and is done on an outpatient basis. Before surgery, anesthetizing drops are placed in the eyes.
Corneal rings are still being studied to treat mild hyperopia and astigmatism, although these uses have not been approved by the FDA. Several other intraocular and corneal implants, from several companies, also are in various stages of clinical study
Eyeglasses--The Old Standby
In some cases, modern technology can provide the best vision correction option. In those cases in which it can't, eyeglasses can often help. Glasses correct refractive errors by adding or subtracting focusing power to the cornea and lens. The power needed to focus images directly on the retina is measured in diopters. This measurement is also your eyeglass prescription.
Like contact lenses, glasses come in all shapes and sizes, offering an array of choices for both function and fashion. Eyeglass frames, for example, are more durable and tout materials such as titanium and new "memory metals." Lenses are thinner, stronger and lighter. Lens options include antireflective coating, light-changing tints, progressive (line-free) bifocal lenses, and polycarbonate--the most impact-resistant lens material available.
Perhaps the greatest troubling aspect for eyeglass wearers is the constant feel of something sitting on the nose, despite such advances as featherweight glasses. Paul Trossevin of Falling Waters, W.Va., knows all too well the uncomfortable feeling of something permanently perched on his nose. Like a scar that never fades, Trossevin's glasses have been with him every day since he was 4 years old. Now 35, he says, "There was a time when I'd have done anything to get rid of my glasses." Or so he thought.
Although he could never wear contact lenses because of the severe flatness of his cornea, Trossevin was a candidate for laser eye surgery. But the one thing he was unable to obtain from any doctor was a guarantee that after surgery he wouldn't see starbursts and halos around lights--a big concern since he drives a good part of the day and plays baseball at night. "The guarantee was everything," he says. "When he couldn't give me that, suddenly my glasses took on new meaning--a guarantee of the good eyesight they have given me for over 30 years."
Looking Ahead
Among some of the more intriguing developments in the vision-correction pipeline is an alternative to LASIK, called LASEK, a new avenue for refractive surgeons that disturbs less corneal tissue than its sound-alike counterpart. There's also talk of investigational devices that could be placed inside the eye to correct refractive errors. Over the next decade, there are sure to be improvements in current techniques and technologies, in addition to new procedures.
