www.pacificvision.org     415.922.9500

Volume 12       June 16, 2008

Innovation. Leadership. Passion for Perfection.

  Eye Health

Melatonin can be bought over the counter in almost any store selling supplements. Many have taken it to help them fall asleep, especially on transcontinental flights, to help regulate sleep-wakefullness cycle. But did you know that our own body produces melatonin? It is produced mainly by the pineal gland in our brain. How does that relate to the eyes? The cue for the release of melatonin begins when the eyes first register the onset of darkness. The rod photoreceptors in the retina begin shedding their outer segments. Retina begins to produce melatonin, then a complex process follows that signals the pineal gland to produce more melatonin. Melatonin is not produced during day time naps because light suppresses its production. If a deeper and longer sleep is desired during the day, the eyes have to be covered to simulate darkness. Keeping the retina healthy as we get older is also important to maintain healthy photoreceptors and healthy levels of melatonin production.

  What's new in vision correction procedures

Maintaining healthy tear film after LASIK, PRK, and Lens surgery is important to good vision. We typically recommend drops that are high in carboxymethylcellulose content, like Refresh Plus or Celluvisc, to lubricate the eye surface. For some people, these may not be sufficient. Recently, we started using a new eye drop, called Optive, to improve tear film after eye procedures. Most eye lubricants simply supply the extra tear volume. But the corneal surface cells may still remain dehydrated. Optive acts on these cells and allows them to take up the water from the tear film. The cells become hydrated, often improving both comfort and vision after refractive surgery.

  Tech Corner

We now have a new way of looking at the health of your cornea. Ocular Response Analyzer (Reichert Ophthalmic Instruments) uses a simple, yet ingenious way of calculating corneal elasticity (or flexibility) by measuring how the cornea responds to a puff of air. If the cornea is very elastic, it may indicate a corneal thinning condition such as a keratoconus, for example. Up to now, we used corneal maps to diagnose such conditions. The maps gave us an image of what the cornea looks like. With Ocular Response Analyzer, we can now analyze how the cornea behaves. This gives us important information for not only determining who is the best candidate for refractive surgery, but also for monitoring eye health in general.

  Fun Eye Facts

Is the wheel really turning? In these illusions, parts of the picture seem to move in the opposite direction of the rest. Why? These kinds of illusions ?move? when the image is seen through your peripheral vision. The periphery of the retina is more attuned to motion and the center of the retina is more attuned to detail. Look closer and you?ll see there are some white lines and some black. The wheel seems to move because your eye flows from the white part to the black parts of the image, over and over again, creating an illusion of motion. To check out more amazing optical illusions go to http://www.ritsumei.ac.jp/~akitaoka/index-e.html

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