Heterochromia

In anatomy, heterochromia refers to a difference in coloration, usually of the irisesbut also of hairor skin.

Heterochromia (also known as a heterochromia iridis or heterochromia iridium) is an ocularcondition in which one iris is a different color from the other (complete heterochromia), or where part of one iris is a different color from the remainder (partial heterochromia or sectoral heterochromia). It is a result of the relative excess or lack of pigmentwithin an iris or part of an iris, which may be inheritedor acquired by diseaseor injury.

Image:Heterochromia iridis 01.jpg Eye color, specifically the color of the irises, is determined primarily by the concentration and distribution of melaninpigment within the iris tissues[1]. Consequently, anything affecting those factors may result in a difference of color being observed.

An excess of pigmentation is usually associated with hyperplasiaof the iris tissues whereas a lack of pigmentation associated with hypoplasia. Although seen in humans, heterochromia in which one iris differs in color from the other iris is more frequently observed in non-human species such as cats(for example, Siamese; white, shorthaired cats can be "odd-eyed" with one copper or orange eye and one blue eye), dogs(for example, Siberian Huskiesas well as Australian Shepherds, Border Collies, and other breeds with merlecoats), and horses(so-called "walled-eyed" horses have one brown and one white eye). Partial or sectoral heterochromia is much less common than complete heterochromia and is typically found in autosomally inherited disorders such as Hirschsprung's diseaseand Waardenburg's syndrome. Image:DogEye2color cr wb.jpg

Classfication based on etiology

Although a distinction is frequently made between heterochromia that affects an eye completely or only partially, it is often classified as either congenitalor acquired with mention as to whether the affected iris or portion of the iris is darker or lighter.

Congenital heterochromia

Heterochromia that is congenital is usually inherited as an autosomal dominanttrait.

Abnormal iris darker

• Lisch nodules- iris hamartomasseen in neurofibromatosis.
• Ocular melanosis- a condition characterized by increased pigmentation of the uveal tract, episclera, and anterior chamber angle.
• Pigment dispersion syndrome- a condition characterized by loss of pigmentation from the posterior iris surface which is disseminated intraocularly and deposited on various intraocular structures, including the anterior surface of the iris.
• Sturge-Weber syndrome- a syndrome characterized by a port-wine stainnevus in the distribution of the trigeminal nerve, homolateral meningeal angioma with intracranial calcification and neurologic signs, and angioma of the choroid, often with secondary glaucoma [2].

Abnormal iris lighter

• Simple heterochromia - a rare condition characterized by the absence of other ocular or systemic problems. The lighter eye is typically regarding as the affected eye as it usually shows iris hypoplasia. It may affect an iris completely or only partially.
• Congenital Horner's syndrome- sometimes inherited, although usually acquired
• Waardenburg's syndrome- a syndrome in which heterochromia presents as a bilateral iris hypochromia in some cases.
• Piebaldism- similar to Waardenburg's syndrome, a rare disorder of melanocyte development characterized by a white forelock and multiple symmetrical hypopigmented or depigmented macules.
• Hirschsprung's disease- a bowel disorder associated with heterochromia in the form of a sector hypochromia. The affected sectors have been shown to have reduced numbers of melanocytes and decreased stromal pigmentation. [3]

Acquired heterochromia

Heterochromia that is acquired is usually due to injury, inflammation, the use of certain eyedrops, or tumors.

Abnormal iris darker

• Deposition of material
  • Siderosis- iron deposition within ocular tissues due to a penetrating injury and a retained iron-containing, intraocular foreign body.
  • Hemosiderosis- long standing hyphema (blood in the anterior chamber) following blunt trauma to the eye may lead to iron deposition from blood products
• Use of certain eyedrops - prostaglandin analogues(latanoprost, isopropyl unoprostone, travoprost, and bimatoprost) are used topically to lower intraocular pressurein glaucomapatients. A concentric heterochromia has developed in some patients applying these drugs. The stroma around the iris sphincter muscle becomes darker than the peripheral stroma. A stimulation of melanin synthesis within iris melanocytes has been postulated.
• Neoplasm- Nevi and melanomatous tumors.

Abnormal iris lighter

• Fuchs' heterochromic iridocyclitis- a condition characterized by a low grade, a symptomatic uveitisin which the iris in the affected eye becomes hypochromic and has a washed-out, somewhat moth eaten appearance. The heterochromia can be very subtle, especially in patients with lighter colored irides. It is often most easily seen in daylight.
• Acquired Horner's syndrome- usually acquired, as in neuroblastoma, although sometimes inherited.
• Neoplasm- Melanomas can also be very lightly pigmented, and a lighter colored iris may be a rare manifestation of metastatic disease to the eye.

Examples

Image:Cat - different coloured eyes.JPG

Celebrities

• David Bowieis often described as an example, but in fact has two blue irises, with one pupilpermanently dilated due to a childhood injury.
• Kate Bosworthhas blue eyes with a hazel section in one of them.
• Jane Seymourhas one green eye and one brown eye.
• Mila Kunishas one green eye and one blue eye.
• Marilyn Mansonmimics the condition with his trademark left eye contacts, but in fact, possesses two hazel eyes.
• Milla Jovovichhas sectoral heterochromia with brown specks in otherwise blue eyes.
• Christopher Walkenhas one blue eye and one hazel eye.
• Virginia Madsenhas one green eye and one brown eye.
• Dan Aykroyd has one blue eye and one brown eye.
• Tom Fulp, of Newgrounds.com, was born with a brown eye and a blue eye. The blue eye, over time, darkened to brown, but is still a lighter shade.

Images of people demonstrating heterochromia

• Kate Bosworth: [4], [5]
• Jane Seymour: [6], [7]

Fictional characters

Differently-colored irises appear at least as often in fictional characters as in life, and are often employed by an author as being evocative of some particular quality.

• Kazuya Mishimaof the Tekkenseries has a left red eye due to the Devil Gene.
• M. Woland(Satan) of The Master and Margaritaby Mikhail Bulgakovhas one eye green, the other black, as a foreshadow of his bringing chaos to Moscow.
• Conrad Nomikos, protagonist of This Immortalby Roger Zelazny, has a cold blue right eye and a warm brown left eye, indicative of his being either (or both) a mutant and/or a kallikanzaros, a Greek trickster spirit changeling.
• Cloud Strifeof Final Fantasy VII has blue eyes with green highlights. Known in the game as "Mako Eyes", the unnatural green discoloration occurs when a person is exposed to Mako energy.
• Yunaof Final Fantasy X and Final Fantasy X-2 is known for being heterochromatic (one blue eye, one green eye) due to her mixed Al Bhedheritage
• Montgomery from the 1997 Nowherehas one green eye and one blue one
• Jason, Stryker's son, from X2: X-Men United has one blue and one yellow/green.
• Ysanne Isardfrom Star Wars Extended Universe has one red and one blue eye
• Gaeriel Captison, also from the Star Wars Extended Universe, has one green eye and one gray
• Asuna Kagurazaka from the Japanese manga/anime"Negima" has one blue and one dark green eye.
• Oskar von Reuentahl from the anime/novel/mangaseries Legend of the Galactic Heroeshas one blue and one brown eye.
• Kanzaki Urumi from the Japanese manga/anime"Great Teacher Onizuka" has a brown left eye and a blue right eye.
• Subaru Sumeragi of Japanese manga X/1999presumably has heterochromia after the events of the 17th volume of the series (he has one grey-green eye; his right eye was previously blinded then replaced with the hazel colored eye of his dead lover, Seishirou Sakurazuka)
• Hatake Kakashiof manga Naruto possesses one dark eye while his while his red left eye is actually an implant of the sharingan.
• Count Dof the manga/anime"Pet Shop of Horrors" has one purple eye and one golden eye.
• Mayumi Thyme of the Japanese game/manga/anime Shuffle!has one red and one blue eye which reflects her half human, half demon nature.
• Laura from the novel Maya by Jostein Gaarderis described as having one green eye and one brown eye
• Shani Andras, a biological CPU of Gundam Seedhas different colored eyes
• Deliriumfrom the comic"The Sandman", one of the earliest and best known examples. Delirium is a floaty, crazy character with one eye lime green and the other blue with silver speckles.
• Suiseiseki and Souseiseki from the anime and manga Rozen Maideneach have one green eye and one red eye.
• In the original The Crowcomic book miniseries, the protagonist, Eric Draven, has one light and one dark-colored eye (as the comic is in black and white, exact colors are indeterminable) as a result of a ruptured iris following two gunshot wounds to the head.
• In H. P. Lovecraft's story "The Lurking Fear" members of the Martense family of upper New York all share a "hereditary dissimilarity of eyes, one generally being blue and the other brown."
• Spike Spiegelof the anime Cowboy Bebop has brown eyes, but one eye is colored lighter than the other. He says he lost his original eye in an accident, and since then he sees the past through one eye and the present through the other.
• Ephram Brown from Everwood on the WB
• Phèdre nó Delaunay, the main character of Jacqueline Carey's Kushiel's Legacyseries of novels, has a scarlet mote in her left eye.
• Tyrion Lannisterfrom A Song of Ice and Fire has mismatched eyes.
• G.U.N. Commander from Shadow the Hedgehog has one blue eye and one mauve.
• War Prince, Homura from the anime/manga Gensoumaden Saiyuki has one yellow eye and one blue.

External links

• "Heterochromia" by Dr. Peter G. Swannde:Iris-Heterochromie

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This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Heterochromia Wikipedia article Heterochromia.