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Human eye - Coggle Diagram
Human eye
Astigmatism
This occurs when the cornea is not smooth and all suroundings are unfocused and appear blurry. 
Can be fixed with glasses, contact lenses or surgery that fix the unevenness of the cornea
Glaucoma
When the aqueous humour flow can not be drained properly, it causes built up pressure which damages the optic nerve.
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Cataracts
When the nutrients in the (clear) lens of the eye can build up into clumps and over time make the lens foggy. The fogginess doesn't allow for light to come through properly which detraughts vision.
Hyporepia
Farsightness, is when a person has difficulty seeing close objects
The distance between the lens and retina is too small so image appears behind the retina and is blurry
This can be fixed with glasses ( a convex lens) which converges the light rays to appear on the retina.
Myopia
Nearsightedness happens when a person has difficulty seeing far objects. When the distance between the lens and the retina is too large. Images appear to be infront of the retina ( blurry)
This can be fixed with glasses ( concave/diveging lens)
Presbyopia
This often happens with aging. When the eye slowly losses the ability to focus on objects. Can be fixed with glasses.
Photoreceptors
Rods: Are used to see in low light conditions.There are about 120 million rod cells in the retina. There is only one kind rod cells
Cones: These are responsible for seeing colour. There are three kinds of cones in the retina, one to interpret red, then green and blue. There are about 6 to 7 million in the retina
How does the eye work?
The eye has, a pupil, iris, retina, optic verse, lens, and many others that all work together to form images of the world
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