Diagram of the Human Eye
The cornea and lens of an eye act together to form a real image on the light-sensing retina, which has its densest concentration of receptors in the fovea and a blind spot over the optic nerve. The power of the lens of an eye is adjustable to provide an image on the retina for varying object distances. Layers of tissues with varying indices of refraction in the lens are shown here. However, they have been omitted from other pictures for clarity.
Source
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"OpenStax College, Physics of the Eye. December 25, 2012."
http://cnx.org/content/m42482/latest/
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