Science Notes by Ahmet Arduc - Seeing Inside Your Eye

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Seeing Inside Your Eye
Science Notes by Ahmet Arduc - www.ahmath.com

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Science Notes by Ahmet Arduc - Seeing Inside Your Eye

  1. 1. Seeing Inside Your Eyes by Ahmet Arduc – www.ahmath.com
  2. 2. PARTS OF THE EYE STRUCTURE FUNCTION Blind spot: small area of the retina where the optic nerve leaves the eye: any image falling here will not be seen Cornea: transparent tissue covering the front of the eye: does not have blood vessels; does have nerves Iris: circular band of muscles that controls the size of the pupil. The pigmentation of the iris gives "color" to the eye. Blue eyes have the least amount of pigment; brown eyes have the most. Lens: transparent tissue that bends light passing through the eye: to focus light, the lens can change shape Optic nerve: bundle of over one million axons from ganglion cells that carry visual signals from the eye to the brain Pupil: hole in the center of the eye where light passes through Retina: layer of tissue on the back portion of the eye that contains cells responsive to light (photoreceptors) Sclera: tough, white outer covering of the eyeball; extraocular muscles attach here to move the eye.
  3. 3. As an object gets further away less of its light will reach your eye. The image takes up less space on your retina (the light-sensitive tissue at the back of your eye), making the image smaller. This makes details of the image harder to see.
  4. 4. The Blind Spot Each of your eyes has an area on the retina which does not have any receptors. This is because this area is occupied by the optic nerve. So any image which falls on these receptors will not be seen. To see this, close your left eye and look at the + in the image below. Move your right eye in closer to the + and then move farther away. At some point, the circle on the right will disappear. That is because it is in your blind spot.
  5. 5. You don’t notice your blind spot though, because your brain fills in the area with an image based on what is around it. This is a cognitive illusion. To see this, close your left eye again and look at the + in the picture below. Move closer and further away until the red X disappears. At just the right spot, it will look like the line has filled in where the X was.

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