20 Fascinating Facts About Eyes

If you’re looking at these words right now, your eyes are doing far more than you can even imagine processing what you see.

That’s because it takes millions of moving parts working together in your eyes to make vision possible. Given all that they do, these sensory organs qualify as an engineering and biological marvel.

To get a clear 20/20 view of just how special eyes are, take a peek at these 20 facts from ophthalmologist Allison Babiuch, MD.

1. The six muscles in each of your eyes move faster than any other muscles in your body. Your brain uses these zippy muscles to control eye movement through three cranial nerves.
2. Your eyes grow along with the rest of your body during childhood. They get considerably larger in your first two years of life and then experience another growth spurt during puberty. Eyes typically reach full size in early adulthood.
3. Human eyes typically end up about 24 millimeters (mm) wide. (That’s slightly less than an inch for those more familiar with the Imperial system of measurement.)
4. For comparison’s sake, the largest eyes among land animals belong to the ostrich and are about 50 mm (or 2 inches) in diameter. The largest eyes at sea belong to the giant squid and are about the size of a dinner plate.
5. When the lenses in your eyes focus an image on your retina, it’s upside down and backward. Your brain reorients and right-sizes the image for you while “developing” what you see.
6. Seven million photoreceptor cone cells in your retina bring you the world in living color. Your brain can interpret an estimated 10 million different colors, too. (No wonder why we have so many paint options!)
7. Despite being able to see so many different colors, cone cells only detect three — red, green and blue. Your brain combines signals from that trio to show you a full rainbow of hues.
8. Color blindness occurs when certain color-detecting cones are missing. Around 300 million people around the world have some form of color blindness. Men are more likely to be color blind.
9. Your retina is also home to more than 100 million photoreceptor rods that help you see in dark and dim conditions. Rods are extremely sensitive and respond to even a few photons of light
10. Photoreceptor rods don’t assist with color vision but they do help you see up to 500 different shades of gray.
11. Babies are born with blurred vision that gradually improves during their first few months in the world. It takes about four months for an infant to fully see colors and distant objects.
12. Ever notice how a baby’s eyes might suddenly cross or even seem out of synch? These unusual movements are common as a newborn’s vision develops and they learn how to focus.
13. Tears are less common at the beginning and the end of life. Newborns don’t start producing tears until they’re between 1 and 3 months old. The older you get, the fewer tears you produce.
14. The color of your eyes is as unique as your fingerprints, with no two people sharing the same hue. Shades of brown are the most common color. Variations of green are the rarest.
15. Eye color doesn’t typically change after your first year of life. If it does switch, it could be a sign of an issue that deserves attention from an eye doctor.
16. Need another reason to stop smoking cigarettes? Smoking and secondhand smoke increase your risk for cataracts, macular degeneration and other issues that could cost you your vision.
17. Having two eyes helps with depth perception. Your brain computes distances by comparing the distinct images from each eye.
18. A vision change may signal the emergence of larger health issues like diabetes, high blood pressure or various inflammatory diseases.
19. Sunglasses aren’t just an expression of style. They’re a way to keep your eyes healthy by blocking harmful ultraviolet (UV) sunlight that can harm your vision over time. Your risk of sun-related damage is higher if your eyes are lighter in color, too.
20. Blinking is a basic reflex to protect your eyes. On average, adults blink about 14 to 17 times a minute. That adds up to between 13,440 and 16,320 blinks a day if you’re awake for 16 hours.

Pretty cool stuff, huh? Clearly, a lot is happening in your eyes at any given moment. That’s why it’s important to make sure they stay healthy — and a big part of that involves getting regular vision checkups, says Dr. Babiuch.

It’s generally recommended that children get their vision screened and adults get a comprehensive eye exam every year or two. Visits should be more frequent if you use corrective lenses or are at a higher risk of eye disease.

Schedule an appointment if you suddenly feel like you’re not seeing as well, too.

“It’s amazing what our eyes are capable of doing,” says Dr. Babiuch, “but that doesn’t mean they don’t need your help to stay healthy.”