ABSTRACT
Although the eyes are relatively small, they are important to one’s well-being and they are complex in structure.
The eye is a spherical body that is covered mainly by three coats of tissues: the sclera, choroids, and retina. These coats mainly consist of, respectively, fi brous tissues; pigments and blood vessels; and nerve fi bers, cells, and special receptors. They are nontransparent. However, light is admitted through the front of the eye, where the three coats are replaced by a number of tissues, notably the cornea and the lens (Fig. 16.1(A)).
