Search results
Results from the WOW.Com Content Network
The sclera, [note 1] also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective outer layer of the eye containing mainly collagen and some crucial elastic fiber. [2] In the development of the embryo, the sclera is derived from the neural crest. [3]
The human cornea borders with the sclera at the corneal limbus. In lampreys , the cornea is solely an extension of the sclera, and is separate from the skin above it, but in more advanced vertebrates it is always fused with the skin to form a single structure, albeit one composed of multiple layers.
The eye is made up of three coats, or layers, enclosing various anatomical structures. The outermost layer, known as the fibrous tunic, is composed of the cornea and sclera, which provide shape to the eye and support the deeper structures.
Surface ectoderm forms the lens, corneal epithelium and eyelid. The extracellular mesenchyme forms the sclera, the corneal endothelium and stroma, blood vessels, muscles, and vitreous. The eye begins to develop as a pair of optic vesicles on each side of the forebrain at the end of the fourth week of pregnancy.
The corneal limbus (Latin: corneal border) is the border between the cornea and the sclera (the white of the eye). The corneal surface is one of the body's most specialized structures, undergoing continuous cellular renewal and regeneration. [1] It contains limbal stem cells in its palisades of Vogt.
Standard contact lenses cover the eye’s cornea. However, gas-permeable scleral lenses are specially made to sit on the sclera, which is the whites of the eyes.
The uvea (/ ˈ j uː v i ə /; [1] derived from Latin: uva meaning "grape"), also called the uveal layer, uveal coat, uveal tract, vascular tunic or vascular layer, is the pigmented middle layer of the three concentric layers that make up an eye, precisely between the inner retina and the outer fibrous layer composed of the sclera and cornea.
The sclera and cornea form the fibrous tunic of the bulb of the eye; the sclera is opaque, and constitutes the posterior five-sixths of the tunic; the cornea is transparent, and forms the anterior sixth. The term "corneosclera" is also used to describe the sclera and cornea together. [1]