STORY BYBasic LASIK surgery patients are finding out that not all 20/20 is created equal.
“Lower order” eye aberrations that can be detected with standard vision screening, such as near or far-sightedness, or astigmatism respond well to LASIK, the five-minute laser correction, heavily advertised and made famous by Tiger Woods.
Higher order irregularities, however, like haze, glare, blur or poor night vision can’t be corrected with standard LASIK. They might even be induced or worsened by the corneal cut that LASIK requires.
However when you combine LADARVision, the only FDA approved wave front measuring system for laser surgery with the LASEK procedure, you get “custom cornea”—correction that’s uniquely personalized for each patient’s eye.
At the Hermann Eye Center in Houston, this high-tech combo is producing crystal-clear results, says corneal specialist Richard Yee, the only refractive surgeon in Houston to perform the integrative procedure.
CustomCornea (a registered name) is so super-specific to your eye’s geography, that near-perfect “line-of-sight” vision is the predicted outcome.
“We are now able to measure the individual blueprint or ‘fingerprint’ of the cornea, interface the data with the laser, and correct not only the patient’s lower-order aberrations, but also the irregularities that couldn’t be measured before,” says Yee, also clinical professor at The University of Texas Medical School at Houston.
“Customizing the laser treatment to match each eye’s characteristics is what gives you the haute couture of personalized vision correction,” Yee says.
CustomCornea’s success begins with an understanding of the differences between LASIK and LASEK, Yee explains, who no longer uses LASIK in his arsenal.
In LASIK a cut is made into the cornea to create “a trap door” requiring a thick cornea to work with. “The trap door is pulled back, the corneal surface, lasered, and then we reseat the trap door.”
There’s no post-op pain and the healing time is short because “we cover everything back up, which is why we get that next-day ‘wow’ effect,” Yee says.
The problem is that the cut itself can create glare, haze or halos that either weren’t there before, or worsen pre-existing aberrations.
“LASIK patients would often complain about blur, haze, bad night vision even though they’re testing at 20/20 post-op,” he says.
LASEK “only rolls back the carpet” —the outer layer of the cornea. “Since we don’t cut a trap door, we actually have more tissue to work with, which offers greater structural stability and a larger range of vision correction. When it heals, there’s no cut, no seam,” Yee says.
But most of the 1.2 million Americans who opt for laser correction each year don’t request LASEK because even though the vision may be better, it takes longer to heal and there is some post-op pain. “Rolling back the carpet means it takes a little longer for the corneal surface to reattach itself,” Yee says.
Neither surgical style alone can yield crisp, sharp predictable results. The LADARWave measuring device’s data that contains the eye’s blueprint must be coupled with the laser’s computer to produce “supervision.”
“You’ll not only see 20/20, but the quality of the 20/20 will be better,” Yee says.
The CustomCornea system uses a low-energy laser beam which shines
through the cornea, bounces off the back wall of the eye, and back
through corneal surface, so that any obstruction to the light wave
can be measured and mapped. The “map” is then coupled
with the computer in the LADARVision laser, providing exact correction
measurements unique to that eye.
LADARVision also tracks the eye at about 4,000 times per second to compensate
for the minute reflexive movements our eyes make. With the LADARTracker, “we
can ensure an accurate laser beam placement, no matter how much the eye
is tracking,” Yee says.
For more information:http://www.uth.tmc.edu/ophthalmology/RWYee/index.html
UPDATED: 5-22-2003
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Dr. Richard Yee is a clinical professor in the Department of Ophthalmology and Visual Science at the UT Medical School.
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Food Irradiation
and Safety
On August 22, 2008, the Food and Drug Administration (FDA) published a final rule that allows the use of irradiation to make fresh iceberg lettuce and fresh spinach safer and last longer without spoiling.
Irradiating fresh iceberg lettuce and spinach will help protect consumers from disease-causing bacteria such as Salmonella and Escherichia coli O157:H7 (E. coli). Illnesses from these bacteria range from uncomfortable symptoms to life-threatening health problems.
The foods affected by the final rule are
Irradiation (also sometimes termed "ionizing radiation") is a process of treating products with a measured dose of radiation. Food irradiation is not new. FDA has conducted irradiation safety evaluations for more than 40 years and has determined the process to be safe for use on a variety of foods.
After studying the safety of irradiating fresh iceberg lettuce and fresh spinach, FDA has determined that these greens, when irradiated under the conditions specified in the final rule, retain their nutrient value and are safe to eat.
FDA considers irradiation a complement to, not a replacement for, proper food-handling by producers, processors, and consumers. Irradiation is just another tool to reduce the levels of disease-causing microorganisms on fresh iceberg lettuce and fresh pinach.
Irradiation does not take the place of washing. FDA continues to recommend that consumers wash fresh and bagged produce before eating unless the packaging specifically states that the product has been pre-washed.
For more information, go to: http://www.fda.gov)
