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Ferrets with Waardenburg syndrome have a small white stripe along the top or back of the head and sometimes down the back of the neck (known as a "blaze" coat pattern), or a solid-white head from nose to shoulders (known as a "panda" coat pattern). Affected ferrets often have a very slightly flatter skull and wider-set eyes than healthy ferrets.
A 2002 study found the prevalence of blue eye color among the white population in the United States to be 33.8% for those born from 1936 through 1951, compared with 57.4% for those born from 1899 through 1905. [15] As of 2006, one out of every six Americans, or 16.6% of the total US population, has blue eyes, [63] including 22.3% of whites.
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]
Human Eye. Cyanopsia is a rare visual phenomenon characterized by a blue tint to vision. Most commonly associated with cataract surgery and certain medications, such as sildenafil, cyanopsia is typically a temporary side effect rather than a standalone disease.
The four pigments in a bird's cone cells (in this example, estrildid finches) extend the range of color vision into the ultraviolet. [1]Tetrachromacy (from Greek tetra, meaning "four" and chroma, meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye.
Colors of confusion include blue/purple and green/yellow. [2] Deuteranopia is a severe form of red-green color blindness, in which the M-cone is absent. It is sex-linked and affects about 1% of males. Color vision is very similar to protanopia. [2] Tritanopia is a severe form of blue-yellow color blindness, in which the S-cone is absent. It is ...
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 ...
Blue eyes are also found in southern Europe, Central Asia, South Asia, North Africa and West Asia. [58] [59] Approximately 8% to 10% of the global population have blue eyes. [35] A 2002 study found that the prevalence of blue eye color among the white population in the United States to be 33.8% for those born from 1936 through 1951.