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The Sense of Sight
Transcript of The Sense of Sight
The process of sight starts when light passes through the cornea, pupil, lens and hits the retina. When on the retina light energy causes chemical changes. The nerve fibers join on the optic disk which travels on the optic nerve. The optic nerves from both eyes join in the optic chiasm. The overlap of fibers allows depth reception. Electrical impulses are brought to the visual cortex on the optic nerve. When in the brain it figures out what it is looking at and turns the image right side up. This whole process happens almost instantly.
How do people go blind?
Going blind means losing your sense of sight. One of the main causes of blindness is Cataracts. Cataracts are clouding of the lens in the eye. Common symptoms of Cataracts are blurry vision, colors seem faded, Glare, not being able to see well at night, double vision and frequent prescription changes in your eye wear. Another leading cause of blindness is Glaucoma. Glaucoma is when the optic nerve is damaged. The cause of Glaucoma is when high pressure in your eye. The high pressure in your eye damages your optic nerve. When your optic nerve is damaged an image can't travel on the nerve. When you go blind you need to use your other senses more and adjust to life without sight.
What is the most important part of the eye?
Each part of the eye is important in it's own way. I will explain how each part is important. The cornea is important because it protects your eye from dust particles, germs and other harmful chemicals. Also the cornea helps focus light. In fact it contributes more than 65-75% of the eyes focusing ability. The pupil is important because it lets light through to the lens and retina. The iris is important because it it opens and closes the pupil and knows the right amount of light through to the inner eye. The lens is important because it focuses light and balances it on the retina. The retina is important because it is the part that creates the image, focuses light, sends it to the optic disk, uses rods for low levels of light, and cones for high levels of light and colors. The optic disk is important because it sends the image the retina made to the optic nerve. The optic nerve is important because it sends the image to the brain. The brain is important because it tells you what you are looking at and turns the image right side up.
Why do darker colored irises offer more protection than lighter colored irises?
The reason darker colored irises offer more protection than lighter colored irises is because lighter irises are more sensitive to light than darker irises. Lighter iris colors include blue, green and other light colors. They are that way because of absent pigments called melanin. These lighter colors are do to a scattering of light called the Rayleigh scattering. It is the same physical process that explains why the sky is blue. The Rayleigh scattering is when light scatters when it hits a small object.
Why do some animals see better at night?
Most animals that can see in the dark are nocturnal. Nocturnal animals usually have big eyes. For example an owls eyes take up 1/2 of its skull. The bigger the eye the bigger the iris can open the pupil. The bigger the pupil the more light can enter through to the inner eye. Also a bigger cornea means light can enter the eye at more angles then a regular sized eye. Owls eye's are packed with rods. The photosensitive pigment in rods, rhodopsin, is particularly sensitive to low levels of light.
The Sense of Sight
Have you ever wondered how you see? This presentation will answer that question