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The irises of human eyes exhibit a wide spectrum of colours. Eye color is a polygenic phenotypic trait determined by two factors: the pigmentation of the eye 's iris [ 1 ][ 2 ] and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris. [ 3 ]: 9. In humans, the pigmentation of the iris varies from ...
Heterochromia iridum. Heterochromia is a variation in coloration most often used to describe color differences of the iris, but can also be applied to color variation of hair [1] or skin. Heterochromia is determined by the production, delivery, and concentration of melanin (a pigment). It may be inherited, or caused by genetic mosaicism ...
Color blindness or color vision deficiency (CVD) is the decreased ability to see color or differences in color. [2] The severity of color blindness ranges from mostly unnoticeable to full absence of color perception. Color blindness is usually an inherited problem or variation in the functionality of one or more of the three classes of cone ...
Periorbital dark circles. Minor dark circles and a hint of periorbital puffiness —a combination principally suggestive of minor sleep deprivation. Periorbital dark circles (including dark circles of the lower eyelid) are dark blemishes around the eyes. There are many causes of this symptom, including heredity and bruising.
Heterochromia iridum is the name of this rare phenomenon. It occurs when the iris—the colored part of the eye surrounding the pupil—exhibits two different colors. Most cases of heterochromia ...
Rhodopsin, also known as visual purple, is a protein encoded by the RHO gene [5] and a G-protein-coupled receptor (GPCR). It is the opsin of the rod cells in the retina and a light-sensitive receptor protein that triggers visual phototransduction in rods. Rhodopsin mediates dim light vision and thus is extremely sensitive to light. [6]
pɪˈtiːkɪə. Specialty. Rheumatology. A petechia (/ pɪˈtiːkiə /; [1] pl.: petechiae) is a small red or purple spot (≤4 mm in diameter) that can appear on the skin, conjunctiva, retina, and mucous membranes which is caused by haemorrhage of capillaries. [2][3] The word is derived from Italian petecchia ' freckle ', of obscure origin. [1]
Light brown iris with a distinct limbal ring. A limbal ring is a dark ring around the iris of the eye, where the sclera meets the cornea. [1] It is a dark-colored manifestation of the corneal limbus resulting from optical properties of the region. [2] The appearance and visibility of the limbal ring can be negatively affected by a variety of ...