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The Human Eye is a Truly Amazing Organ
The optic nerve and the
central retinal blood vessels enter the back of the eye at the disc (also called the blind
spot). The back 2/3 of the eye is called the retina and gives us our wide field of
view vision. It contains millions of rod and cone cells which convert light energy
into electrical signals sent to the brain via the optic nerve. The macula (6x7 mm)
is the tiny spot on the retina where finer detail focus occurs. The fovea (1.5 mm)
is just behind the macula where the highest concentration of cone photoreceptors are
concentrated. Light rays are focused by the lens onto the fovea for straight ahead
vision and fine detail. The sclera is the tough outer wall of the eye and the
choroid is the thin spongy layer between it and the retina filled with blood vessels.
Another detailed picture of the complete eye can be found at
http://www.dallas.net/~tra/leaflets/normal.htm
Autor: Brian A Harron,Kinburn,Ontario,Canada,K0A 2H0
Modificado em: 18-01-1999
