Show Mobile Navigation
Health

10 Eye-Popping Facts About Vision

Jana Louise Smit


There’s more to vision than just looking at stuff. The gift of sight is a complex marvel of mysteries and incredible feats., from colors only certain people can see to color nobody can see, the remarkable adaptations of the deaf to the dreams of the colorblind. These are just some of the things that make the window of the soul worth gazing into.

10Blue-Eyed Chinese

1

Photo credit: ADG

A Chinese boy with sky-blue eyes can allegedly see and write in pitch darkness. According to Nong Yousui’s teachers and the reporters who tested him, he can complete a questionnaire in the dark, and when examined by a flashlight, his eyes flare a luminous green. At night, a cat’s eyes reflect light in the same way. This made some believe that Nong was born with an incredible mutation: acute night vision never before seen in humans.

If he truly has feline eyes, the flash effect should show up on video—which it doesn’t. Also, scientists dismiss the very idea. Any mutation of this caliber doesn’t happen overnight. Though Nong’s uncanny ability is plausible if his eyes have extra light receptors, the whole thing could also be fake. Either way, given his race, the blue eyes remain mesmerizing—something scientists believe could be a form of albinism.



9Seeing Stars

2

Whether you’re seeing stars, flashes, experiencing visual disturbances from migraines, or a light show after rubbing the eyelids, it’s all caused by the same thing: pressure or stimulation of the retina.

The eyeball is filled with a thick gelatinous fluid that keeps the eye round. Sometimes this gel can press against the retina and its center responsible for creating pictures in the brain. It can happen when the eyes are rubbed vigorously, a powerful sneeze shakes the retina or stimulates the optic nerve, or even when a person stands up too fast. The latter occurs when dropping blood pressure and the oxygen-deprived brain affects the sight parts of the eye. Any message from the retina gets interpreted by the brain as light, whether there is actual light involved or not.

8The Gender Difference

3

Men and women look at things differently. Together, both will see the same movie, but men will be more sensitive to smaller details and movement. Women will be more aware of different color hues and how they change.

During a conversation, the sexes also focus differently. Men are more likely to watch the other person’s lips while they’re talking and will be more easily distracted by movement behind the speaker. When women listen to someone talk, they tend to alternate their gaze between their companion’s eyes and body. Other people, rather than movement, are more likely to divide their visual attention.



7The Speed Of Color

4

Never mind the secret life of bees. Their eyesight is far more intriguing. The tiny insects can detect color three to four times faster than people do. At first glance, it appears to be a wasted ability. Most objects carry a permanent hue and this type of vision also expends a lot of energy. Yet, bees have it.

The little honey makers have evolved their eyesight around finding flowers, which means being able to identify certain colors with accuracy. While petals and blooms don’t exactly change their own shades every second, something else can. Researchers think this skill helps bees when they are confronted with flickering light. A speedy flight through a bush could cause colors to shift rapidly due to changing light and shadows. In such a case, fast color vision will allow bees to track each abrupt change in shade.

6Deaf Vision

5

Individuals born deaf tend to have peripheral vision that is more sensitive to movement and light. The explanation could be a brain adaptation. Whenever a person looks at something, two pathways in the brain process the information. One assesses the object’s position and motion while the other is all about recognition. During motion-tracking experiments, the first pathway showed enhanced activity in the deaf and most likely is the reason why peripheral sight is stronger in them.

Another experiment suggests the deaf can also use their sense of touch to develop visual acuity. Two study groups received a flash near the corner of the eye. During this, the hearing participants received two beeps, and the deaf got two puffs of air to the face. Both reported the same hallucination of seeing two flashes. In deaf cats, the hearing part of their brain also appears to sharpen their peripheral vision.

5Why We See In 3-D

6

Three-dimensional vision helps with depth perception. Each eye views an object from a slightly different angle. Called binocular disparity, it helps the brain to gauge depth. It’s vital but not the only way to view the world in 3-D.

The parallax phenomenon is the difference in speed at which things move as you pass them. It’s most notable while driving: nearby trees will shoot past, while a radio tower in the distance moves at a snail’s pace. Other ways to calculate an object’s range include their size, being able to see more detail in closer objects, parallel lines that appear to converge, and the way items stand in relation to each other.



4The Forbidden Colors

7

There are colors humans can’t see. This isn’t colorblindness but something that happens to everybody. Called “forbidden colors,” they are two-toned hues that can’t be seen by the naked eye because they cancel out each other’s frequencies. These mischievous elves are red-green and yellow-blue.

The same retina cells that activate when we see something red also deactivates in the presence of green. This dampening of cell activity registers as green in the brain. They both can’t happen at the same time and thus cannot be perceived together as a single hue. The same thing happens with yellow and blue.

Researchers are divided into two camps. There are those who believe forbidden colors can be produced and seen by humans during certain image experiments. But others argue the results are yet-unnamed intermediate shades of the known colors but not the true forbidden colors.

3The Gray Realm

8

Researchers have possibly uncovered why the world appears gray to depression sufferers. A study involving patients with major depression found that, compared to healthy individuals, their retinas were less responsive—in a dramatic way—to especially black-and-white contrasts. This was true even for the participants who were taking antidepressants. Researchers believe the link between depression and vision could be the substance dopamine.

Healthy contrast vision depends on certain cells within the retina. Called amacrine cells, they connect the brain cells in the retina with each other. Pulling double duty, dopamine is needed for these cells to work properly as well as making a person feel driven and focused. When the chemical is lacking, it can cause cheerlessness and possibly blunt the effectiveness of the amacrine cells. This could be why everything look like an old photograph to sufferers during times of depression.

2Dreamscape Of The Color-Blind

9

Individuals with colorblindness can dream in color. Just how much depends on when the person turned colorblind.

When somebody is born seeing the world in shades of black, white, and gray, that will be the environment of their dreamscape. Should they become colorblind later, their colorful past can spill over into dreams. Anyone with other forms of colorblindness, such as the common inability to distinguish between reds and greens, will dream in their own range of the rainbow. For instance, they will dream of a green Santa Claus instead of a red one because that is also their waking reality.

It is also extremely uncommon for those with normal vision to dream in black and white. Difficulty remembering colorful dreams could be because during sleep, the dreamer is more occupied with doing something or reaching a destination than focusing on their dreamscape’s hues.

1The Rainbow Women

10

Some women can see more color than the rest of population—not just an extra shade here or there but in technicolor most of us can’t even comprehend. Called tetrachromats, they see vivid colors where others merely perceive monotone shades. It’s a literal rainbow world, and it seems to be an exclusive female one.

Everyone has three kinds of cone cells in their eyes and each reads a different light bandwidth. They combine frequencies to recognize individual colors. An extra cone adds hundreds of combinations and a huge extra set of colors. It’s estimated that about 12 percent of women might have an extra cone, but not all of them are tetrachromats. The true ones are rare, and they don’t always have it easy. Because this genetic condition remains widely unknown, they are seldom believed whenever they attempt to share their magical sight.