The Eyes Have It!


– By Stephen Cohen, O.D.

Happy New Year! Hopefully, included in your resolutions is taking care of your most precious sense: your vision. We were not designed for the current demands on our eyes. If we were, we’d have one eyeball in the middle of our foreheads! For a little diversion, here are some (hopefully) interesting facts about eyes and vision.

Our eyes are composed of more than two million working parts, processing 36,000 bits of information every hour (who did they find to count that?). The eyes can distinguish 200 separate colors (which could make for an impressive Crayola Crayon set!). Our eyes contribute to 85 percent of our total knowledge, and utilize 65 percent of all pathways to our brain. Our two eyes working together is what provides us with depth perception (3-D vision).

In nature, while a worm has no eyes at all, an ant has two eyes that are actually made up of many smaller eyes. An ostrich eye is two inches across, but weighs more than its brain. The giant squid, at 18 inches across (the size of a beach ball), has the largest eyes. In addition to vision, a frog’s eyes help to push food down its throat (really!). The human front of the eye has three layers, but a cow’s has eight layers to protect it from injury while grazing along the ground. Dogs cannot distinguish between reds and greens (I wonder how they told us that). An owl can see a mouse moving more than 150 feet away with light equivalent to a candle (poor mouse). On the other hand, an elephant can see about 100 yards, the size of a football field (but once they see something, they “never forget it”…sorry…couldn’t resist).

Babies cry, but don’t produce tears until up to three months after birth. It can also take several months before a baby’s permanent eye color is established. Of all the muscles in our body, the eye muscles are the most active. We blink (which re-coats our eyes with new tears) about 12 times per minute, and an average blink lasts about one-tenth of a second. Conversely, when we work on a computer, our blink rate can decrease by up to 60 percent. Each of our eyelashes has a “life span” of about five months. Up to 80 percent of the ultraviolet radiation (which can contribute to cataracts and other eye disorders) we are exposed to in our lifetime occurs by 18 years of age. And, last but not least, Elton John is purported to have over 4,000 pairs of glasses (I wonder if he gets a volume discount?).

Aren’t you glad you asked?

Photo credit: Sanctuary photography → back ! maybe :p via / CC BY-NC-SA

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