Definitions for scleraˈsklɪər ə
This page provides all possible meanings and translations of the word sclera
Random House Webster's College Dictionary
a dense, white, fibrous membrane that, with the cornea, forms the external covering of the eyeball.
Category: Anatomy, Ophthalmology
Origin of sclera:
1885–90; < NL < Gk sklērá (fem.) hard
sclera, sclerotic coat(noun)
the whitish fibrous membrane (albuginea) that with the cornea forms the outer covering and protection of the eyeball
The white of the eye. It is the tough outer coat of the eye that covers the eyeball except for the cornea.
Origin: From σκληρός.
The sclera, also known as the white of the eye, is the opaque, fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In humans the whole sclera is white, contrasting with the coloured iris, but in other mammals the visible part of the sclera matches the colour of the iris, so the white part does not normally show. In the development of the embryo, the sclera is derived from the neural crest. In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly, fatty deposits on the sclera can make it appear slightly yellow. Human eyes are somewhat distinctive in the animal kingdom in that the sclera is very plainly visible whenever the eye is open. This is not just due to the white color of the human sclera, which many other species share, but also to the fact that the human iris is relatively small and comprises a significantly smaller portion of the exposed eye surface compared to other animals. It is theorized that this adaptation evolved because of our social nature as the eye became a useful communication tool in addition to a sensory organ. It is believed that the conspicuous sclera of the human eye makes it easier for one individual to infer where another individual is looking, increasing the efficacy of this particular form of nonverbal communication. Animal researchers have also found that, in the course of their domestication, dogs have also developed the ability to pick up visual cues from the eyes of humans, making them one of only two species known to seek visual cues from another individual's eyes. Dogs do not seem to use this form of communication with one another and only look for visual information from the eyes of humans.
U.S. National Library of Medicine
The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. It receives the tendons of insertion of the extraocular muscles and at the corneoscleral junction contains the canal of Schlemm. (From Cline et al., Dictionary of Visual Science, 4th ed)
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