Spot Eye Exam

Why Do People Have Blind Spots

This episode was proudly made possible bythe allnew 2015 Subaru Legacy. It's not just a sedan, it's a Subaru. Can you see everything on the screen withoutmoving your eyesé Look at me did you see thaté Didn't think so.a Howdy lookers, thanks for tuning into DNews,I'm Trace. Eyes are little 1 inch diameter balls (2.54 cm) tucked in your head, and thoughthey're magnificent, human eyes aren't even CLOSE to the best in the animal kingdom. Infact, your brain is tricking you into thinking your eye is seeing things that aren't thereRIGHT NOW. We've all got blind spots that

we can't see, and huge sections of our visionare just… wrong! Take a piece of paper with a dot and a pluson it. Close one eye, hold the paper close to your face and look straight at the dot,pulling it away slowly. Eventually, the plus should disappear! That's your blind spot.If you switch eyes, the dot should disappear. You might have to try it a couple of times.To understand WHY this happens, we have to go inside the eye. If you could fly into the pupil and insidethe eyeball to look around you'd be floating in vitreous humor of the inner eye. It's aclear, gellike material. On the walls of

the eye, you'd see blood vessels streamingeverywhere, and spread across the back of the eye you'd see the rod and cone cells ofthe retina. Rods are for low light, cones are for color and visual detail. If you got closer to the retina, you couldspot the macula right in the middle with only cone cells that's the only part of yourvision that you can see clearly. If you look at my face here, you can see it clearly, butwhile still looking at my face pay attention to the walls around me, or my shirt. It'sVERY difficult to comprehend the rest of your visual field. The macula is truly the onlypoint of visual clarity!

From there, you could follow the nerves ofthe retina, like following a bunch of extension cords to the wall. Eventually, you'd get tothe optic disk; a part of the eye with no rods or cones. That's where the optic nerveenters the eyeball! It's kind of like where your eye plugs in. And it causes a blind spot.There's nothing there for your eye to perceive since there are no rod or cone cells! My eye was nice enough to send me apicture of the inside of my own eye. You can see the macula here, and the optic nerve here.That is my point of clarity, and my blind spot!

If it seems stupid to have a blind spot, you'reright. Cephalapods don't have one, because their optic nerves run BEHIND the retina ratherthan in front of it. Think of it this way, cephalopods have their wiring inside the walls,but because of an unfortunate evolutionary mutation, mammals didn't and thus we all haveblind spots. The reason you don't see this spot all thetime is because your brain fills it in. Try doing the dot and plus experiment with a pieceof colorful paper and your brain will fill it in with color. That's your brain trickingyou into thinking your vision is perfect, when it's really not. Silly brain, tricksare for nonscientists.

Blind spots are very important to be awareof especially when you're driving! That's why we wanna thank Subaru for making thisepisode possible. And especially the allnew 2015 Subaru Legacy. Every sedan has its benefits,but only one combines them all. It's not just a sedan. It's a Subaru. If you could have the eyes of another animal,which would it beé Catsé Eaglesé Cephalopodsé Mantis Shrimpé!We're watching for your comments, so leave one. Thanks for watching DNews. Here's lookingat you, kid. Please subscribe.

Eye Tests That Look Like Magic

blind spots. human eyes have a blind spot when the optic nerve exits the back in the eye. this area has no light receptors because the nerve is in the way you can find your blind spot with this test. look at the red cross on the left with your right eye closing your left eye, move your head slowly closer and further away quot;So weirdquot; at a certain distance the blue dot on the right will disappear

pause if you need to, you've just found your blind spot After images, stare at the white dot in the center of the image and try not to blink. your eyes have three types of cones or color receptors red, green and blue. after images appear when you stare at a particular color for too long and those color receptors get tired. so when you suddenly switch to looking at a black and white image

those tired receptors aren't working as well this leaves an afterimage of the reverse colors. See your veins. blood vessels and veins feed the photosensitive cells in your eye to keep them alive these blood vessels cast shadows on your retina here's how you can see those veins. poke a small hole in a post it note or piece of paper hold that against a bright white background like your computer screen

look to the hole while shaking the postit slightly you should see a shadowy network online sort of like the veins a leaf these are the veins in your eye quot;Oh, wowquot; Gross. dominant eyes most people have a dominant eyes, I'm meaning that one eye gives more priority information than the other eighty percent of people are right eye dominant see which is your dominant eye. make a triangle between your thumbs and

forefingers With both eyes open, look at an object several feet away Center the object inside the triangle, close one eye and then the other. your dominant eye will look like this and your nondominant eye it will look like this. it's almost visionary. see what I did there.

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