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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]
In some cases, additional tests such as a color vision test, optical coherence tomography (OCT), or an electroretinogram (ERG) may be used to check for retinal or optic nerve abnormalities. Neurological evaluation may be necessary if cyanopsia is accompanied by other neurological symptoms.
A 1997 study of White Americans found that eye color may be subject to change in infancy, and from adolescence to adulthood. [ 24 ] 17% of children experienced a change of eye color by adulthood. Of those children, 50% of developed lighter eyes as they got older.
[1] [2] [3] The fibrous tunic, also known as the tunica fibrosa oculi, is the outer layer of the eyeball consisting of the cornea and sclera. [4] The sclera gives the eye most of its white color. It consists of dense connective tissue filled with the protein collagen to both protect the inner components of the eye and maintain its shape. [5]
Leukocoria (also white pupillary reflex) is an abnormal white reflection from the retina of the eye. Leukocoria resembles eyeshine , but leukocoria can also occur in animals that lack eyeshine because their retina lacks a tapetum lucidum .
Being color blind can change this, and there have been some verified reports of people with four types of cones, giving them tetrachromatic vision. [ 4 ] [ 5 ] [ 6 ] The three pigments responsible for detecting light have been shown to vary in their exact chemical composition due to genetic mutation ; different individuals will have cones with ...
An Ishihara test image as seen by subjects with normal color vision and by those with a variety of color deficiencies. A pseudoisochromatic plate (from Greek pseudo, meaning "false", iso, meaning "same" and chromo, meaning "color"), often abbreviated as PIP, is a style of standard exemplified by the Ishihara test, generally used for screening of color vision defects.
The cooperative eye hypothesis is not the only one that has been proposed to explain the appearance of the human eye. Other hypotheses include the proposal that white sclerae are a sign of good health, useful in mate selection, or that eye visibility promotes altruistic behaviour by letting people know they are being watched. A study by the Max ...