Are There Blind Spots in Our Eyes?
Our eyes are vital organs because they help us visualize our surroundings. But are our eyes perfect in seeing what’s right in front of us? Sadly I learned in our evolution, nature messed up at one point and gave us blind spots in our eyes. This project shows why we have these blind spots, how to discover them, and how big they are. I researched on how our eyes see things; why when one eye is closed, the other eye sometimes can’t see what’s in front of it. I also found during my research a formula that is used to estimate the size of a human eye’s blind spot. I performed an experiment using Blind Spot Test card I made to verify the existence of blind spots in my eyes. I also collected data while testing to find the size of my blind spot. I learned the size of eyes’ blind spots varies in relation to the size of the human eyes.
Are there any blind spots in our eyes? If there are, how do we find them, and how big are they?
Dependent Variable: Size of the blind spot in our eye
Independent Variable: Diameter of the eye
Controlled Variables For Each Group
Child Test Subject
Adult Test Subject
If I close one of my eyes, using a test card marked with different symbols then I can find my other eye’s blind spot. Add a ruler/yard stick to take measurements; I can estimate the size of that blind spot too. I think the bigger the human eye, the bigger the blind spot is.
The following diagram shows the anatomy of a human eye (New Translation of Laruelle’s ‘Biography of the Eye’).
Our eyes see things when light reflects off the objects goes through the pupil and sends the information to our brains. The eye and brain work together as a group that after the information gets delivered to the brain as electro-chemical signal, it is interpreted, or “seen”, as images (WebMD).
The first layer of our eye is the cornea. It is made of a clear tissue and protects the eye like a see through glass cover. More importantly, it helps the eye focus on an object while light passes through it. The iris, a colorful part of the eye around the pupil behind the cornea contracts or dilates to control the amount of light that goes into the pupil. The pupil at the center of the iris is an opening that lets the light into the eye (Your Eyes).
After light enters the pupil, it passes through the lens behind. The lens functions just like a camera lens so that it focuses the light and beams it onto the retina, the light receptor at the back of the eye. The retina’s surface is flat and smooth, and it acts like a movie screen or the film of a 35mm camera. However, unlike a screen or a film, the retina also has some other features, one of which is the light sensors that detect light. After the retina detects light, it converts the light into electro-chemical signals. These signals then exit the back of the eye via optical nerves and get sent to the brain for processing (WebMD).
There is a little area on the retina where the optical nerves are attached to the eyeball at one end and connects to the brain on the other end. This spot of the retina contains no light sensors. Without light sensors the retina cannot sense light, therefore if light hits that spot, it cannot convert the light into electro-chemical signal and pass the information to the brain to “see”. This forms a blind spot on the eye. The blind spot however, doesn’t affect our vision because our brain “ignores” it. Also having a pair of eyes, one eye can back up the other eye’s blind spot so that we have a clear vision most of the time. This is why people usually don’t notice the effects of blind spots (Kingfisher 114).
There are ways to test human eye’s blind spot. Scientists also discovered formula to estimate the size of our blind spots. Depending on the size of our eyes, we each have unique blind spots.
A cardboard card...
Cited: 1. “Blind Spot: To see, or not to see”, Exploratorium, http://www.exploratorium.edu/snacks/blind_spot/index.html
2. “New Translation of Laruelle’s Biography of the Eye”, Fractal Ontology, Nov 21, 2009 http://fractalontology.wordpress.com/2009/11/21/new-translation-of-laruelles-biography-of-the-eye
3. “The Kingfisher Science Encyclopedia”, Kingfisher Publications, 2006
4. “Your Eyes”, Kids Health, http://kidshealth.org/kid/htbw/eyes.html
5. “Your Guide to How the Eye Sees”, WebMD, http://www.webmd.com/eye-health/amazing-human-eye
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