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The iris consists of two layers: the front pigmented fibrovascular layer known as a stroma and, behind the stroma, pigmented epithelial cells.. The stroma is connected to a sphincter muscle (sphincter pupillae), which contracts the pupil in a circular motion, and a set of dilator muscles (dilator pupillae), which pull the iris radially to enlarge the pupil, pulling it in folds.
When viewed at large angles from the side, the iris and pupil may still be visible by the viewer, indicating the person has peripheral vision possible at that angle. [ 15 ] [ 16 ] [ 17 ] About 15° temporal and 1.5° below the horizontal is the blind spot created by the optic nerve nasally, which is roughly 7.5° high and 5.5° wide.
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.
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The second pair of iris screens, circa 1710–1716, was also painted with ink and color on gold-foiled paper, and measure 163.7 by 352.4 centimetres (64.4 in × 138.7 in) each. [ 11 ] Unlike the earlier pair of iris screens, this later pair includes a depiction of an angular bridge, a more explicit reference to the literary work that inspired ...
Light enters the eye through the pupil, and the iris regulates the amount of light by controlling the size of the pupil. This is known as the pupillary light reflex. The iris contains two groups of smooth muscles; a circular group called the sphincter pupillae, and a radial group called the dilator pupillae. When the sphincter pupillae contract ...
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One of the most fundamental elements of art is the line. An important feature of a line is that it indicates the edge of a two-dimensional (flat) shape or a three-dimensional form. A shape can be indicated by means of an outline, and a three-dimensional form can be indicated by contour lines. [1]