The Eye
Learning objectives
- Know the layers and chambers of the eye.
- Be able to describe the pathway of light.
- Know the structure and function of the components of the anterior segment.
- Know the organization of the retina and be able to relate this to the transduction of light and transmission of signal to the optic nerve
General Topography of the Eye
Though its shape is not quite spherical, the eye is referred to as a globe (eyeball). Thus, the anterior pole is the center of the corneal curvature, while the posterior pole corresponds to the point of greatest curvature of the posterior segment. The geometrical axis is the line joining these two poles. The visual axis is the line drawn from the center of the fovea to the apparent center of the pupil.
In a horizontal section through the eye, three layers of the eyeball can be distinguished: the outer corneo-scleral coat; the middle uvea containing the choroid, the ciliary body and the iris; and the inner retina. The conjunctiva is a thin, transparent mucous membrane, which lines the posterior surfaces of the lids and the anterior part of the globe up to the cornea. The portion which belongs to the lids is called palpebral and the one clothing the eyeball, the bulbar conjunctiva. Its secretion provides protection for the cornea.
This laboratory exercise includes an examination of a model of the eye and of a microscopic slide of a horizontal section through an eye.