Health - General
By: - at August 18, 2013

Top 15 Amazing Facts About Your Eyes

The human eye is one of the most interesting and important sensory organs in the human body. Though small and delicate, the eye heals extremely quickly in healthy people and the human eye can recover from seemingly insurmountable damage. Most people are struck with a certain level of fear at the idea of losing their eyesight.

Closeup of human eye

Seeing is critical to most people’s job, hobbies, and quality of life. So it is understandable why everyone should be concerned about protecting and taking care of their eyes. Here are the top 15 facts about the human eye.


15)  Eyes Heal FAST
It may seem strange for a gooey and not very firm part of your body to be the best healer that you have. However, the eye is a very complex organ and its purpose is to do everything that it can to work. This means that it will work hard to heal itself when it is damaged. The most common issue that people have with their eyes is called a corneal abrasion. A corneal abrasion is a scratch on the cornea of your eye. These can be caused by makeup brushes, chemical splashes, scratching, dirt, or anything that would invade the surface of your eye. The good thing about these injuries is that minor ones heal within a matter of hours as long as the eye is properly flushed and you do not rub it. Deeper scratches and abrasions can take longer to heal, but your eye typically manages this on its own. Serious damage can occur from things that you wouldn't think would be harmful. One of the most commonly removed objects from a patient's eye in emergency rooms is off all things, a mascara brush. During automobile accidents, patients sometimes accidentally lodge this everyday beauty product right into their eye. 

The Human Eye
human eye

It’s important to remember to not poke at or rub your eye. Just blink, flush out with lukewarm clean water or saline solution, and wait. Resisting the urge to touch at your eye will prevent further irritation and issues from occurring. If you do experience discomfort for more than a day, however, you should consult your eye doctor as you may need some antibiotic drops to help avoid possible infections. For the most part, eyes heal themselves very quickly as long as you are in good health and do nothing else to irritate it.


14)  Blue and Green Eyes are Recessive Traits
blue eyeMost people have dark colored eyes. This is because the gene that gives some people blue or green eyes is called a recessive trait. Recessive traits are types of genes that are easily pushed aside or hidden by other genes in a DNA sequence. This is why if you have two parents, one with brown eyes and one with blue, the odds of their children having brown eyes is greater than the odds of their children having blue. This doesn’t mean that two brown eyed parents cannot have a blue eyed child, as there is no way of really predicting if a recessive trait will make itself pronounced or not. However the odds are distinctly stacked in the dark eyed gene’s favor.

In fact, blue and green eyes can be traced back to a single mutation from one person who lived around the Black Sea over 8,000 years ago. These findings explain that you don’t have a gene that creates blue eyes (the gene itself is called OCA2, if you’re interested in that sort of thing). Instead what it does is turn off the ability for your body to create brown eyes.


13)  Your Eyes Grow the Least (70% of your size at birth)
baby eyesYou may have heard the saying that your eyes do not grow at all with your body. When you look at a newborn’s wide, questioning eyes, this may seem very true. Babies of all mammals are known for their large eyed gazes. Certainly, it really does seem that babies’ heads need to “grow into” their eyes. It’s easy to see where the idea that your eyes are the same size from the day that you are born gained acceptance.

This is not entirely true. The human eye begins to develop quite early in the gestation phase. When you are born, your eyes are about 66% of the size that they will be when you are an adult. Most babies have eyes that are about 18mm in diameter at birth with levels of variation. Adults typically reach about 24mm. While there are variations on eye size from person to person, the averages hold true. This is engrained in us as “normal”, and why when we see someone with unusually small or large eyes, we take notice.


12)  Everyone Has a Blind Spot
But you won’t ever notice it. Both of your eyes have a small blind spot where your optic nerve goes back into your brain. This area of the retina is different from person to person, and everyone has a blind spot. So why can’t you see them? That is because your eyes are built with that blind spot in mind. Your blind spots are placed symmetrically so that one eye will compensate for the other. Consider how your vision shifts if you cover one of your eyes. The eye that is uncovered almost immediately adjusts to widen your field of vision. People who are blind in one eye typically adjust rather quickly to the loss of vision because of how quickly our eyes compensate for one another.

blind spot concept

If you don’t believe us, you can try the following trick to locate your blind spot. Take a blank sheet of paper and divide it into two sections. In the middle of one section draw a back dot. Make the dot large enough to be easily seen, but don’t let it dominate the page. On the other side of the paper, draw a line and then write three or four rows of letter and or numbers. Cover the eye that is directly in front of the letters or numbers and move your paper to 3 or 4 times the length of the line away from your face. Individually look at each letter or number till you notice the dot “vanish”. Your other eye will have the same sized blind spot, symmetrically across.


11)  You Won’t Go Blind Reading in Dim Light
dim lightingYou really can’t go blind if you read something in dim light. The reason that this myth came about was that many people feel a level of eye “strain” from reading without backlighting or reading in darkened rooms. Your eyes are not actually being damaged in the process, they are just working harder than they usually would. Your eye sees shapes and colors by refracting light. This is why you need a fairly specific balance of light sources to see properly. Your eyes are controlled by muscles and these muscles have to work harder to compensate for light sources that are outside of your comfort level. Bright lights can make your eyes feel as “tired” as dim ones.

It’s also interesting to note that your eyes will actually complete pictures for you in half light or light that is otherwise unclear. This is because your brain is used to seeing certain images and settings, and will compensate for what you cannot actually see. However, when you’re doing something where the landscape is changing such as reading a book, watching TV, or writing on a computer screen, your brain doesn’t have the completed picture on deck. This also adds to further eye strain as your eyes attempt to get as much information as possible.


10)  Eye Color is Dictated by the Iris
While it was mentioned above that a mutation that removes the ability for your eyes to be brown is what makes them green or blue, this gene is driven by your iris. Your iris – the colored part of your eye- is where the pigmentation that determines your eye color is located. All babies are born with bluish colored eyes because it takes some time for the pigment to develop. Baby’s eyes do not “change color” as much as they are filled in with the color that they will have as an adult.

Human Iris Close-up
Human Iris Close-up

Human eye color is based off of three genes (green, blue, and brown). Other eye color combinations are still being studied. The reason that eye colors do not come out as a blend of your parent’s eyes is because of the way that the body selects the chromosomes that will go into making the color. Without getting into the genetic details, eye color is not like mixing two shades in a paint bucket as much as it is picking two selections out of a color wheel, then going with one of them or the other.





9)  Newborns Can’t Make Tears
It isn’t that babies cannot cry. Anyone who has been in a room with a newborn for more than a few hours is well aware that they can indeed kick up a fuss if the mood strikes them. However, when babies are born they do not have the ability to produce enough tears to do more than protect their eyes. When you’re born your eyes are in the process of finishing up preparing for life in the outside world, and you are in the process of growing. Like eye color, it takes about a month or so for babies’ tear ducts to produce enough tears to actually form tear drops.

human eye and tear

Your baby is producing tears from the moment they are born, but they are only producing enough to protect the eye and keep it lubricated. This is why even though your little baby’s face is scrunched up and they are wailing away, their cheeks will be totally dry. As the glands develop it’s important to keep an eye out for blockage. If the baby seems to be excessively weeping, not weeping at all, or has swelling of the tear ducts, it’s best to see a doctor immediately.


8)  Sit as Close to the TV as You Want
sitting close to tvIf you are feeling any leftover longing to push your nose up against the TV from your childhood, you can go ahead and do it now. Sitting close to the TV will not ruin your eyes at all. No one really knows where the myth began (maybe those old CRT "box" television sets produced too much radiation), however it is a distinct possibility that some parents were tired of trying to watch TV through their child and came up with a good way to discourage them. The fact of the matter is that the worst you are going to get from sitting too close to the TV, is a case of eye strain.

Eye strain goes away after spending some time simply resting them, and you won’t see any permanent damage. The reason that your eyes feel strained when sitting too close to a digital picture, has to do with your eye’s main purpose. Your eyes work constantly to send your brain a complete picture of your surroundings. When it cannot give your brain a picture that makes sense, the muscles in your eyes are going to work harder in an effort to complete an image.


7)  Your Eye Muscles Work the Hardest
Even though your eyes are not what you may think of first when you think of muscles, your eyes are the strongest muscle in your body by size, and the ones that get the most use. Your eye remains in place because of the balance of three pairs of muscles that work together. Each muscle acts in opposition to the others. This tension keeps your eye “floating” in the socket. If one of these muscles is damaged in any way the opposing force will literally pull your eye in its direction, and cause strain along with difficulty to focus.

Anatomy of the Human Eye
Anatomy of the Human Eye

Your eye muscles move faster than any other muscle group in your body. Every motion of your eye requires at least seven different coordinated muscle movements. These movements are completed almost without you thinking about it as your eyes naturally are attracted to movement. However, the mere act of sweeping your eyes across your desk and looking for a pen uses hundreds of coordinated muscle contractions in measured bursts that you won’t even notice are happening.


6)  20/20 Vision is Actually Normal
We hear a lot about 20/20 vision in the United States (it is called 6/6 vision in metric). It actually isn’t “superior” vision. Instead, 20/20 refers to how much a “normal” person can see standing 20 feet away from an eye chart. This is why when you go to the eye doctor’s room for an exam the room seems so long. When you have 20/20 vision you can see what most people see when standing 20 feet away from the eye chart. The ratio will change depending on how well your eyes register things on the chart. For example 20/30 vision means that a person who is standing 20 feet in front of a chart sees things as clearly as a normal person who is standing 30 feet from the chart would. Anyone who has a vision rating at 20/200 or further is considered legally blind in the United States.

Close-up of Eye Examination Equipment
Close-up of Eye Examination Equipment

You can also have better than average vision. 20/15 vision means that standing 20 feet from a chart you would see something as clearly as a normal person standing 15 feet from the same. Many people who get laser vision correction report that they are able to see better than 20/20 after their operation, though there is always some variance. The best humans can get according to recorded medical records is 20/10.


5)  Your Eyes Correct a Lot
targeted eye correction flipping imageThe major focus of our eyes is to make sense of the world around us. This means that even if you are looking at an object upside down, your eyes are going to make an effort to “flip” the item around so you can view it properly. This is why when you were a kid and sat upside down against the sofa to look at the TV, you most likely encountered some eye strain. Whenever your eyes are working overtime you are going to experience muscle tiredness.

One of the most interesting things about the eye is how it strives to give your brain enough information to complete a picture of what you are looking at. For example, if you are used to seeing something at a certain angle and suddenly you were to put on glasses with it upside down, your eyes would actually work to flip the image “the correct” way. Most optical illusions take advantage of the fact that your brain and eyes are working continuously to make sense of the world around you.


4)  Blinking
By simply going about your day you blink enough to have your eyes closed for half an hour. Studies have shown that the average person blinks up to twenty times per minute. When you take all the numbers and do the math to include the average time in a day you spend sleeping, you will find out that you spend 10% of your life with your eyes totally shut. Blinking isn’t simply a twitch that everyone has, but rather it serves a set of very important purposes.

young buisiness woman blinking

When you blink, you are effectively cleaning your eyes like a set of windshield wipers across your car. The blink pushes around lubricated tears, and can push out debris before it settles in and scratches the delicate surface of your eye. Aside from that, somewhat obvious purpose to blinking, scientists in Osaka University in Japan have figured out that our brains actually use that split second of blink time as a “soft reset” of sorts. When you blink, your brain is taking a mini rest to compile the information that it’s gathered and sent to your brain. If you are feeling strained and overwhelmed, closing your eyes for a few moments will give you a chance to calm down because it gives your eyes a chance to rest. You cannot simply choose to focus on something dull. As long as your eyes are in taking a light source they are working. You cannot shut your eyes down any other way than closing them. When you blink, you’re giving the most active organ in your body a chance to take a much needed breather.


3)  Your Eyes are Complex
How eyes actually work is a complicated science that takes years of dedicated study to master. This is because the eyes are not just a series of soft lenses that can be adjusted to get a proper picture. The lenses, corneas, retinas, muscles and tendons that make up the eye are comprised of 2 million working parts. Yes, two MILLION working parts. The way that these parts are arranged and interact is the reason that you can see the way that you do. Some of the cells in your eye are shaped differently in certain sections than they are in others. This is because the way the lenses are formed is what refracts light.

The human eye

We still are not able to transplant one person’s eye to another person because of how complex eyes actually are. The understanding of how all the parts individually come together is becoming more complex as our science expands. However 80% of all eye problems are now considered correctable.


2)  Heterochromia
Eye colors are much different from simply mixing one parent’s eye color with another. Instead there are two major chromosomes that make up your eye color, the right and the left. Typically the same chromosome is chosen for each eye. However, there are instances where this doesn’t happen. The result is a person with two different colored eyes, a condition known as heterochromia.

Person With Heterochromia
Person With Heterochromia

The term heterochromia does not only mean eyes of two different colors. It can also include skin and hair. You can have partial or complete heterochromia, each has different results in the human body. Complete heterochromia means that the irises of a person’s eyes are two different colors, such as blue and green or hazel and brown. Partial heterochromia happens when the irises are almost completely the same color, but a small part of one eye will be a different color. This is most common in dogs and cats.


1)  Eye Cameras are a Thing
The human eye’s ability to heal makes surgical work on it a fairly smooth, if very precise process. Many different surgeries are available to try to repair eye blindness and correct vision. However, we are still far away from being able to transplant one biological eye from one person to another. The delicate retina of your eye makes this process impossible with current technology. However, that does not stop science from trying to replace the eye with another alternative.

Eye Camera Concept
eye camera

In Biomedical circles and IEEE magazines there have been talk of ocular cameras that are wired directly into the human brain. Recently, a construction worker who had one eye ruined due to an accident with cement mixing had one of these tiny (they are smaller than a thumb nail) cameras implanted into his eye socket. This camera was wired into the man’s brain and works off of the same electrical impulses that a biological eye needs to work. While the camera cannot see in color and does not have the level of focus that its biological counterpart has, this new device is shedding light on how eyes work. This advanced technology gives hope to the 39 million people worldwide who suffer from some form of blindness.


Conclusion
The human eye is an amazing organ that allows us to easily navigate the world. Eyes quite literally allow us to make sense of the world around us, and strive to work with our brains in a complex way to complete the picture of our reality. When your eyes are damaged or strained, it makes you feel disoriented and irritable. Eye headaches are some of the worst pain that a person can experience. Eye strain from poor light settings on monitors is swiftly becoming one of the leading causes of eye strain and related migraines. These migraines can defiantly affect a person’s quality of life, and even keep them from doing their jobs.

closeup of human eye

Because the eye is so important it’s no wonder that a lot of myths surrounding their proper care have cropped up in our society. However, the eye is a lot heartier than you may give it credit for. It is the only organ capable of recovering from a major and invasive surgery in less than 72 hours. On top of that, it is the only organ other than our skin that comes into direct contact with the outside world and atmosphere. The complex system of cells and muscles (over 2 million different parts) focus a series of biological lenses that refract light in order to tell us size, distance, color, and allow us to judge how fast something is moving. Knowing all of this it gives a lot more credence to the idea that your eyes are your window to the world.



 

 

 

 

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