Common questions
I do not understand how what I am 'looking at' becomes 'what I see'. Can you explain?
This is an especially valuable question, one that relates to almost everything that we see and do. The human eye works very much like a camera; although this comparison is an oversimplification, it is helpful in explaining how you see.
Like a camera and its lens, the eye has a refracting, or light focusing, system. When you look at an object, rays of light travel from that object into the lens system of the eye just as rays of light travel from an object into the lens system of a camera.
The rays first pass through the cornea, the clear tissue that covers the iris, or coloured part of the eye. As light filters through the cornea, the rays bend inwards, travelling through the pupil, or hole in the centre of the iris, and continue onwards to the lens itself. Just as a camera lens narrows or bends light rays so that they meet in focus on the film in the back of the camera, the lens of eye narrows the light rays so that they meet and focus on the retina in the back of the eye.
The retina receives the image of the object you see and then transmits it by way of the optic nerve to the brain. But the retina can record only what it receives. If the image sent to the brain is sharp, then that is the picture you see. If the image is blurred, you may need corrective glasses or contact lenses.
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