The sclera is the outer thick layer of the eye, but it does not cover the entire eye. It is often referred to as the white of the eye.
Light first passes through the cornea, which bends and focuses it.
The iris controls the dilation of the pupil and adjusts the amount of light entering the eye.
The lens does the final focusing of light entering the eye.
The ciliary muscles control the thickness of the lens, which affects the focus of light on the retina.
The optic nerve is a bundle of ganglionic cell axons that exits the back of the eye and transmits the light signal to the brain for interpretation.
Rods transmit black and white images as well as low-intensity light. Rods only have one pigment: rhodopsin.
Cones transmit colored light. There are three types of cones, each containing a different pigment (red, blue and green).
The retina is the location where light is imaged at the back of the eye. Once it hits the retina, it is transmitted through photoreceptors and the optic nerve.
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