From blind spots in our retinas to an eyecolour that didn't exist until recently, we count 40 bizarre facts about our own eyeballs40 Human eyes blink an average of 17 times aminute. This equates to 14,280 times a day or 5.2 million times a year. 'Blinking removes debris from the eye's surface by spreading tears over it. The tears helpmoisten and lubricate the eyes. They also have antibacterial properties. 38Eyes heal quickly. With proper care, corneal
abrasions can repair within 48 hours. 37Newborns don't produce tears. While they do make crying sounds, their tears don'tstart flowing until they are 4â€“13 weeks old. 36Approximately six in a thousand people are born with heterochromia iridus. This is acondition where the person's eye are two different colours. 35A 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. 34Schizophrenia can be diagnosed with 98.3% accuracy using a simple eye test that trackseye movement abnormalities. 33Dogs are the only species other than humans that seek visual cues from other individuals'eyes. Dogs only do this when interacting with humans. 32â€˜Impossible' or â€˜forbidden' colours
are colours that are too complex for the humaneye. Although it is impossible to perceive them under regular viewing conditions, theycan be seen in special circumstances 31The 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. 30It's possible for your eyes to be sunburned. Prolonged sun exposure eventually leads toa thickening of the eye tissue, which might require eye surgery.
29Your retinas perceive the outside world as upsidedown. The brain must then flip andmake sense of the image. 28Eye colour â€“ or our perception of it â€“ can change with lighting conditions. Neither bluenor green pigments are present in the human iris or ocular fluid. 27Octopus eyes have no blind spot and evolved separately from vertebrate eyes. This is anexample of convergent evolution. 26Up until 10,000 years ago, brown was the only
known human eye colour. This changed whena person living by the Black Sea developed a genetic mutation that made their eyes blue. 25If one red eye appears in a flash photograph, there is a chance this person has a strandof treatable eye cancer called Leukocoria. For this test to work, both eyes must be lookingdirectly at the camera. 24Human retinas cannot detect the colour red. Our â€˜red' receptor only detects coloursin the yellowâ€“green spectrum; thus, our brains must combine multiple signals to perceivered.