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medium spring-open used to cut the external side of the cornea, fine sutures; iris, etc. •de' Wecker's iris scissors: small slender spring-open scissors for intraoccular maneuvers (iris and deeper and more delicate structures); has two wings to operate it and one sharp and one blunt blade. •Vannas' scissors
Tenon's capsule (/ t ə ˈ n oʊ n /), also known as the Tenon capsule, fascial sheath of the eyeball (Latin: vagina bulbi) or the fascia bulbi, is a thin membrane which envelops the eyeball from the optic nerve to the corneal limbus, separating it from the orbital fat and forming a socket in which it moves.
The total number of genes that contribute to eye color is unknown, but there are a few likely candidates. A study in Rotterdam (2009) found that it was possible to predict eye color with more than 90% accuracy for brown and blue using just six SNPs. [16] [17] In humans, eye color is a highly sexually dimorphic trait. [18]
Trichromatic color vision is the ability of humans and some other animals to see different colors, mediated by interactions among three types of color-sensing cone cells. The trichromatic color theory began in the 18th century, when Thomas Young proposed that color vision was a result of three different photoreceptor cells .
The human eye can detect a luminance from 10 −6 cd/m 2, or one millionth (0.000001) of a candela per square meter to 10 8 cd/m 2 or one hundred million (100,000,000) candelas per square meter. [ 19 ] [ 20 ] [ 21 ] (that is it has a range of 10 14 , or one hundred trillion 100,000,000,000,000, about 46.5 f-stops).
An organism's "eye color" is actually the color of one's iris, the cornea being transparent and the white sclera entirely outside the area of interest. Melanin is yellowish to dark hazel in the stromal pigment cells, and black in the iris pigment epithelium , which lies in a thin but very opaque layer across the back of the iris.
Redness of the sclera is typically caused by eye irritation causing blood vessels to expand, such as in conjunctivitis ("pink eye"). Episcleritis is a generally benign condition of the episclera causing eye redness. Scleritis is a serious inflammatory disease of the sclera causing redness of the sclera often progressing to purple.
An antibiotic/steroid combination eye drop is put in, and an eye shield may be applied, sometimes supplemented with an eye patch. [7] A well constructed scleral tunnel should be self-sealing, but if it does not seal sufficiently, one or more sutures will be added. [7] [1]