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The human eye has about a total of. Dioptres of refractive power.The cornea has.D approximately and the lens has.D.The Cornea has an index of refraction of about1. and the lens has1. of indice of refraction.AS light travels in a straight line from an object to the eye.As it meets the cornea,aqueous,lens,vitreous ,it is been refracted i.e bends as it travels until it comes to a focus on the macular area of the retina where it seems an image is been seen clearly.In the real sense,this image appears in an upside down position but its the duty of the Human brain to interprets its transmission through the Optic Nerve and the visual pathway where it is seen as a normal standing image.
eye is a very important element for seeing objects, it works like a camera, and sends the taken pictures to the brain, first of all the light faces the cornea that is transparent and its power is about 42-44 D (about 75% of the total power) , when the light enter the eye by the cornea, it passes through the aqueous humor to the lens which is biconvex, flexible and can accommodate according to the object distance (zooming just like a camera), then through the vitreous humor to the retina which is the neural layer of the eye. the captured image then sent to the brain by the optic nerve.
The eye is an essential element for our vision. its shape is almost spherical and contains a lens and the retina.
Light for outside and objects passes through the lens and produce an image on the retina. Photo-receptors placed on the retina convert the light to electrical signal, that then goes to our brain. The image is reversed in the eye, and the brain does the nice calculation of reversing it again (so we do not not feel of having the head down ;) ).
