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Volume 18       February 25, 2009

Innovation. Leadership. Passion for Perfection.

  Fun Eye Facts

A newborn baby sees the world upside down because it takes some time for the baby's brain to learn to turn the picture right-side up. Processing visual information is a complex task - it takes up a relatively large portion of the brain compared to other senses. This is because your brain performs several tasks to make images 'easier' to see. One, of course, is combining the two images, which is helped by the corpus callosum, the tiny part of your brain which joins the two big hemispheres. The other part is handled in the optic part of your brain itself, and part of its job is to make images right-side-up. It does this because your brain is so USED to seeing things upside-down that it eventually adjusts to it. After all, it's a lot easier to flip the image over than it is to try and coordinate your hands and legs with an upside-down world! As a result, for the first few days, babies see everything upside-down. This is because they have not become used to vision.

  Eye Health

Can eating the right stuff keep you seeing great well into old age by reducing the risk of cataracts? Cataracts are opacities in the lens that develop as we grow older. They can cause blurry vision, double vision, glare, and the need to turn up the light when we read as we get older. Researchers in the Department of Preventive Medicine at Brigham and Women's Hospital, Harvard Medical School found that eating food and taking supplements rich in lutein/zeaxanthin and vitamin E was associated with significantly decreased risks of cataract formation. They followed nearly 40,000 female health professionals, age 45 and older, for 10 years, assessing their nutrient intake and following their vision. Participants who consumed the largest amounts of lutein/zeaxanthin -- found abundantly in spinach, broccoli, kale, eggs, corn, and peas -- had an 18 percent lower risk of developing cataracts than the group who consumed the least. The group who consumed the most vitamin E from both food (vegetable oils, nuts, fish) and supplements had a 14 percent lower risk. Wheat germ oil has the highest Vitamin E content of all the vegetable oils.

  What's new in vision correction procedures

How high can you climb after LASIK? Researchers found that LASIK is a good choice for patients involved in high altitude activities, even those who climb the extreme heights. These researchers were actually part of the expedition that climbed Mount Everest. Visual acuity of six Mount Everest climbers was measured at sea level, at base camp (17,600 ft), and as they ascended the 29,035 ft summit. The climbers reported good vision without any changes up to 26,400 ft. Two climbers reported mild blurring of vision at 27,000 and 28,500 feet which improved immediately with descent. No specials precautions are required when ascending high altitude after LASIK.

  Tech Corner

Eye trackers revolutionized the accuracy of laser vision correction. Because a human eye never stands still, how does the laser ?know? where to place the beam? The eye moves on the average 100 times per second. The laser beam, however, needs to land at a precise location on the cornea to correct the imperfections in vision accurately. To solve this dilemma, trackers have been installed within most laser systems. They track the position of the eye and "tell" the laser beam where the eye is at any point in time, so that the laser beam can be right there. Not all trackers are the same, however. Some lasers use trackers that sample eye position at only 60 times per second. Since a typical eye moves faster than that, such sample rate may not be enough for the most accurate results. The sample rate has to be more than 100 times per second. Two lasers have trackers capable of tracking at ultrafast rates -- Wavelight Alegretto (200 times per second) and Alcon LADARVision (4,000 times per second). Even the fastest and most unpredictable eye movements can be followed accurately with these lasers.


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