The basic pattern of all vertebrate eyes is similar. The cross-section of the eyeball can be represented by a circle with one-fifth of its circumference removed. Into this is fitted a clear segment which has a slightly smaller radius of curvature (cornea). The outer coat, which makes up the remaining four-fifths of the eyeball, is a tough fibrous structure whose opaque posterior part (sclera) is continuous with the strongly curved, transparent cornea (Fig. 1.1). The vertebrate eye may be compared to the camera, and this analogy is illustrated in Fig. 1.2.
KeywordsDust Depression Brittle Retina Fibril
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