the eye p. 1

The eye
The eye is a complex sensory organ that provides the sense
of sight.Layers of the Eye:
The eyeball is surrounded by three layers: an outer tough fibrous connective tissue layer (tunica fibrosa) includes the sclera, the white portion, and the cornea, the transparent portion, a middle layer or uvea (tunica vascolosa) composed of highly vascular pigmented choroid , the ciliary body (consisting of ciliary processes and smooth ciliary muscle) and the iris ,and the innermost layer (tunica interna) composed of the photosensitive retina . The retina, the inner layer, includes an outer pigment epithelium, the inner neural retina, and the epithelium of the ciliary body and iris. The neural retina is continuous with the central nervous system through the optic nerve.
The sclera is a white , opaque layer that consists predominantly of dense connective tissue.The sclera is a thick fibrous layer containing flat collagen bundles.The sclera is divided into three layers:
• The episcleral layer (episclera), the external layer, is the loose connective tissue .
• The substantia propria (sclera proper), is composed of a dense network of thick collagen fibers.
• The suprachoroid lamina (lamina fusca), the inner aspect of the sclera, is located adjacent to the choroid and contains thinner collagen fibers and elastic fibers as well as fibroblasts, melanocytes, macrophages, and other connective tissue cells.The junction between the cornea and sclera occurs at the transition area called the limbus located in the anterior region of the eye. In the posterior region of the eye, where the optic nerve.
The cornea is the anterior window of the eye.
The cornea consists of five layers: T