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The iris (pl.: irides or irises) is a thin, annular structure in the eye in most mammals and birds, responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm.
Eye color. 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 light brown to black, depending on the concentration of ...
The human eye is a sensory organ in the visual system that reacts to visible light allowing eyesight. Other functions include maintaining the circadian rhythm, and keeping balance. Arizona Eye Model. "A" is accommodation in diopters. The eye can be considered as a living optical device. It is approximately spherical in shape, with its outer ...
113, 6734. Anatomical terminology. [ edit on Wikidata] An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the eye is a complex optical system that collects light ...
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 ...
The central outermost transparent colorless part of the eye (through which we can see the iris and pupil) is the cornea. Cross-section of the human eye, showing the position of the pupil. The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina. [ 1 ] It appears black because light rays entering ...
Conjunctiva, 13. Uvea with 14. Iris, 15. Ciliary body. The anterior segment or anterior cavity[1] is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens. [2][3] Within the anterior segment are two fluid-filled spaces: the anterior chamber between the posterior surface ...
The human eye, showing the iris and pupil. In 1802, philosopher William Paley called it a miracle of " design." In 1859, Charles Darwin himself wrote in his Origin of Species, that the evolution of the eye by natural selection seemed at first glance "absurd in the highest possible degree". [4] However, he went on that despite the difficulty in ...