How do Human Eyes Stack Up to Animal Eyes?
Whenever you see our five senses listed, sight is usually mentioned first. That’s probably because for most of us sight, more than any of the other senses, defines how we perceive and interact with the world. If you have naturally good vision, or vision that can be corrected with lenses or refractive surgery, your eyes are constantly relaying an amazing wealth of information to your brain, and you probably don’t think you’re missing much of what’s out there.
But have you ever wished your eyes could see clearly in the dark? Wouldn’t it be awesome if you could see a car in your blind spot without having to turn your head? Imagine not needing a scope on your rifle because your eyes can see objects up to two miles away!
Unfortunately, even with “perfect” human eyesight, these superhero-like abilities are beyond our eyes’ capacity. In the case of some animals, however, these incredible powers are part of the equipment with which they are born. For instance, a human with “perfect” 20/20 vision can read letters 1/3 of an inch high on an eye chart at a distance of 20 feet. An eagle, if it was capable of reading, could do it from over 100 feet away. An eagle can spot a moving rabbit from two miles away. Sharp eyesight is so important to eagles that the eyeball of a 10 pound eagle is about the same size as that of a 200 pound human.
Have you ever walked out at night to put something in the garbage, only to find the neighbor’s cat rummaging through it? Isn’t it amazing how the cat can quickly scamper off into the night in almost complete darkness without running into anything? Cats, like many other nocturnal animals, see far better at night than humans do. This is due to a reflective membrane at the back of a cat’s eye. This membrane, known as the tapetum lucidum, pulls in every available scrap of ambient light (assuming there is any; a cat can’t see any better in absolute darkness than you can). If you’ve ever seen the eyes of a cat shining at you from the dark, you’re seeing that membrane at work.
Don’t you hate it when someone sneaks up on you from behind? If you were a goat, you would probably never have to worry about it. Goats’ eyes give them a 320 degree field of vision – the next best thing to having eyes in the back of your head. (In comparison, an average human’s field of vision is about 180 degrees.) Keep that in mind the next time you try to catch a goat. Sneaking up from behind doesn’t work because of their extended peripheral vision.
However, it’s not all bad news for us humans. While cats can see far better than we can at night, they cannot see as clearly in bright light as we can. Cats, as well as dogs, are partially color blind; they cannot distinguish between certain colors as well as most humans. The huge, high-powered eyes of an eagle can barely turn in their sockets, leading to poor peripheral vision. (They compensate partially by being able to turn their heads farther.) In the end, it appears nature has given each species the kind of eyesight it needs to thrive: for cats, this means hunting at night; for eagles, it means spotting small prey from great distance; and for humans, it mean the ability to read and write, use fine tools, and recognize faces.
While we don’t have the super-powered vision of a cat or eagle, how well we see determines our ability to perceive and react to the world around us. What’s important is that our eyes function as intended, but nearly half of all humans have nearsightedness, farsightedness, or astigmatism that impairs that function. Until recently, corrective lenses such as glasses or contacts were the only option for restoring good vision in those people. However, modern laser eye surgery is making impaired vision a thing of the past. If you weren’t born with “eagle eyes,” and if you’re tired of relying on glasses and contact lenses to see your best, contact Hoopes Vision. Our complimentary, no-obligation consultation will let you find out what your options are for vision correction.