From blind spots in our retinas to an eye color that didn't exist until recently, we count 40 bizarre facts about our own eyeballs
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40-Human eyes blink
an average of 17 times a minute. This
equates to 14,280 times a day or 5. 2 million times a year.
39-Blinking removes debris from the eye’s surface by
spreading tears over it. The tears help
moisten and lubricate the eyes. They
also have anti-bacterial properties.
38-Eyes heal quickly.
With proper care, corneal abrasions can repair within 48 hours.
37-Newborns don’t produce tears. While they do make crying sounds, their tears
don’t start flowing until they are 4–13 week sold.
36-Approximately six in a thousand people are born with
heterochromia iridous. This is a
condition where the person’s eye are two different color.
35-A shark’s corneas are very similar to those of
humans’. Because of this similarity,
shark corneas have been used as replacements in human eye surgeries.
34-Schizophrenia can be diagnosed with 98. 3%accuracy using
a simple eye test that tracks eye movement abnormalities.
33-Dogs are the only species other than humans that seek
visual cues from other individuals’ eyes.
Dogs only do this when interacting with humans.
32-Impossible’ or ‘forbidden’ colors are colors that are too
complex for the human eye. Although it
is impossible to perceive them under regular viewing conditions, they can be
seen in special circumstances.
31-The pupil of your eye expands as much as 45%when you look
at someone you love. Similarly, a
person's pupils may dilate when looking at someone they are sexually attracted
to.
30 It's possible for your eyes to be sunburned. Prolonged
sun exposure eventually leads to a thickening of the eye tissue, which might require
eye surgery.
29-Your retinas perceive the outside world as upside-down. The brain must then flip and make sense of
the image.
28-Eye color – or our perception of it – can change with
lighting conditions. Neither blue nor
green pigments are present in the human iris or ocular fluid.
27-Octopus eyes have no blind spot and evolved separately
from vertebrate eyes. This is an example
of convergent evolution.
26-Up until 10,000 years ago, brown was the only known human
eye color. This changed when a person
living by the Black Sea developed a genetic mutation that made their eyes blue.
25-If one red eye appears in a flash photograph, there is a
chance this person has a strand of treatable eye cancer called Leukocoria. For
this test to work, both eyes must be looking directly at the camera.
24-Human retinas cannot detect the color red. Our ‘red’
receptor only detects colors in the yellow–green spectrum; thus, our brains
must combine multiple signals to perceive red.
23-It’s possible for eyesight to improve with age. However, this can be a sign that something is
wrong with a person’s overall health.
22-Your eye’s lens sits behind the iris and is roughly the
size of an M&M candy. Developing a
cataract in your eye is like developing a peanut in that M&M.
21-Our peripheral vision has a very low-resolution, and is
almost black-and-white. But we don’t notice
this because our eyes move and fill in the details.
20-The visual centers in the brain are located at the lower
back part of your head. This is why
people with head injuries can sometimes experience temporary blindness.
19-Tetrachromacy is a rare genetic mutation occurring in 2%
of women. It gives them an extra retinal
cone, allowing them to see 100 million colors.
18-Staring directly into the sun will burn as pot in the
retina, causing permanent blindness.
This is called solar retinopathy.
17-Iris pigmentation develops over the first year of
life. This means our eyes are darker now
than they were when we were newborns.
16-Our eyeballs grow just like the rest of our body. At birth, they are roughly 16 centimeters
wide; by puberty, they will have grown toa maximum width of 24 millimeters.
15-20/20 vision’ isn’t perfect vision. It simply means a
person can see 20 feet in front of them with the same clarity as a normal-versioned
person.
14-If you’re short-sighted, your eyeball is longer than
normal. If you’re farsighted, it’s
shorter than average.
13-The composition of tears differs depending on whether
you’re crying, yawning or have an irritant in your eye.
12-In order for you to see, your brain must interpret the
signals it receives from your eyes.
Optical illusions occur when there are discrepancies between what your
brain and eyes perceive.
11-Our eyes constantly make tiny involuntary jerking
movements called ‘micro saccades’. These
stop objects from fading from our vision.
10-Although the human eye is thought to be capable of
detecting around 10 million unique colors, they only have the capacity to
detect 30 shades of grey.
9-The refractive power of a human eye lens is approximately
18 diopters, roughly one third of the eye’s total power. This makes an eye’s lens quicker than a
camera’s.
8-Human eyes contain 107 million cells – all of which are
light sensitive. Seven million cones
help with the detection of color and detail, while 100 million rods allow us to
distinguish black and white. This means
that less than a tenth of our visual receptors detect color.
7-Human eyes have a small blind spot in the back of the
retina where the optic nerve attaches.
We don’t notice this hole in our vision because each eye works together
to fill the other’s blind spot.
6-The human eye can only make smooth (non-saccadic) motions
if it’s tracking a moving object. A
person cannot will their eye into making a smooth motion.
5-Pirates used eye patches to quickly adjust their eyes from
above to below deck. They would have one
eye trained for the bright light and the other for dim, below deck lighting.
4-All kittens are born with blue eyes, which– if they are
going to do so – will change color by around 8 weeks of age. 65–85%of all white cats born with blue eyes
are deaf.
3-To detect nocturnal predators, many animal species will
sleep with one eye open. One hemisphere
of their brain is asleep while the other is awake.
2-Our two eyes give us depth perception. Comparing two images allows us to determine
how far away an object is from us.
1-People generally read 25% slower from a computer screen
compared to paper. Reports also suggest
that late-night screen-reading may be damaging to our eyes.
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