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These spasms can affect any segment, or portion, of the iris and involve the iris dilator muscle. [1] Contractions of the iris dilator muscle, a smooth muscle of the eye running radially in the iris, [2] can cause irregular distortion of the pupil, thus making the pupil look tadpole shaped and giving this condition its name. Episodic segmental ...
The iris (pl.: irides or irises) is a thin, annular structure in the eye in most mammals and birds that is 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 is defined by the iris.
A coloboma (from the Greek κολόβωμα, meaning "defect") [1] is a hole in one of the structures of the eye, such as the iris, retina, choroid, or optic disc.The hole is present from birth and can be caused when a gap called the choroid fissure, which is present during early stages of prenatal development, fails to close up completely before a child is born.
The color of the mammalian, including human, iris is very variable. However, there are only two pigments present, eumelanin and pheomelanin . The overall concentration of these pigments, the ratio between them, variation in the distribution of pigment in the layers of the stroma of the iris and the effects of light scattering all play a part in ...
Ocular synechia is an eye condition where the iris adheres to either the cornea (i.e. anterior synechia) or lens (i.e. posterior synechia). [ 1 ] [ 2 ] Synechiae can be caused by ocular trauma , iritis or iridocyclitis and may lead to certain types of glaucoma .
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.
Section Iris. Iris adriatica Trinajstic ex Mitic; Iris albertii Reg. Iris albicans – white cemetery iris, white flag iris; Iris alexeenkoi Grossh.
Prominent limbal ring 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]