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A limbal ring is a dark ring around the iris of the eye, where the sclera meets the cornea. It is a dark-colored manifestation of the corneal limbus resulting from optical properties of the region. The appearance and visibility of the limbal ring can be negatively affected by a variety of medical conditions concerning the peripheral cornea.
Contents. Iris (anatomy) This article is about the part of the eye. For other uses, see Iris (disambiguation). The iris in humans is the colored (typically brown, blue, or green) area, with the pupil (the circular black spot) in its center, and surrounded by the white sclera.
Green irises, for example, have some yellow and the blue structural color. Brown irises contain more or less melanin. Some eyes have a dark ring around the iris, called a limbal ring. Eye color in non-human animals is regulated differently.
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 or skin. Heterochromia is determined by the production, delivery, and concentration of melanin (a pigment). It may be inherited, or caused by genetic mosaicism, chimerism, disease, or injury.
The corneal limbus manifests as a dark ring around the iris. Its prominence varies by individual. The corneal limbus is the border between the cornea and the sclera. It is highly vascularised. Its stratified squamous epithelium is continuous with the epithelium covering the cornea.
A Kayser–Fleischer ring in a 32-year-old patient who had longstanding speech difficulties and tremor. Kayser–Fleischer rings ( KF rings) are dark rings that appear to encircle the cornea of the eye. They are due to copper deposition in the Descemet's membrane as a result of particular liver diseases. [1]
Illustration of an iris flower with highlighted parts of the flower. Irises are perennial plants, growing from creeping rhizomes (rhizomatous irises) or, in drier climates, from bulbs (bulbous irises). They have long, erect flowering stems which may be simple or branched, solid or hollow, and flattened or have a circular cross-section.
Lisch nodule, also known as iris hamartoma, is a pigmented hamartomatous nodular aggregate of dendritic melanocytes affecting the iris, named after Austrian ophthalmologist Karl Lisch (1907–1999), who first recognized them in 1937.
The iris is a coloured muscularly operated diaphragm in front of the lens which controls the amount of light entering the eye. At the centre of the iris is the pupil, the variable circular area through which the light passes into the eye.
Brushfield spots are a characteristic feature of the chromosomal disorder Down syndrome or trisomy 21. They occur in 35–78% of newborn infants with Down syndrome. [2] Brushfield spots tend to be obscured by pigmentation of the anterior border layer of the iris in patients with darker irides.