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Heterochromia iridum

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For the tightly packed form of DNA, see Heterochromatin.
Heterochromia iridum
SpecialtyOphthalmology Edit this on Wikidata
An example of heterochromia in a human. The subject has one brown and one hazel eye.
Blue merle Border Collie with blue-and-brown eye.

In anatomy, heterochromia refers to a difference in coloration, usually of the irises but also of hair or skin.

Heterochromia (also known as a heterochromia iridis or heterochromia iridium) is an eye condition 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 pigment within an iris or part of an iris, which may be genetically inherited or due to mosaicism, or acquired by disease or injury.[1]

Eye color, specifically the color of the irises, is determined primarily by the concentration and distribution of melanin pigment within the iris tissues[2][3][4]. Consequently, anything affecting those factors may result in a difference of color being observed.

The affected eye may be hyperpigmented (hyperchromic) or hypopigmented (hypochromic).[5] An excess of pigmentation is usually associated with hyperplasia of the iris tissues whereas a lack of pigmentation is associated with hypoplasia.

Partial or sectoral heterochromia is much less common than complete heterochromia and is typically found in autosomally inherited disorders such as Hirschsprung's disease and Waardenburg syndrome. Famous comedian Dan Aykroyd has heterochromia, as do actresses Kate Bosworth, Elizabeth Berkley, Mila Kunis, Jane Seymour, actor Christopher Walken, and American mixed martial artist Jens Pulver. Musician David Bowie is often thought to have heterochromia, but this is not the case as Bowie's eyes are both blue, only the left eye's pupil is permanently dilated due to a childhood injury.

Heterochromia in animals

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, Japanese Bobtails and Turkish Vans; white, shorthaired cats can be "odd-eyed" with one copper or orange eye and one blue eye, and the Turkish Angora), dogs (for example, Siberian Huskies as well as Australian Shepherds, Border Collies, and other breeds with merle coats), horses (so-called "wall-eyed" horses have one brown and one white or blue eye), and even water buffalo.[6]

Classification based on etiology

An example of sectoral heterochromia. The subject has a blue iris with a brown section.
Other example of sectoral heterochromia. The subject has a green eye with a dark brown line.


Congenital heterochromia is inherited in an autosomal dominant fashion.


Although a distinction is frequently made between heterochromia that affects an eye completely or only partially, it is often classified as either genetic (due to mosaicism or congenital) or acquired, with mention as to whether the affected iris or portion of the iris is darker or lighter.[7]

Congenital heterochromia

Heterochromia that is congenital is usually inherited as an autosomal dominant trait.

Abnormal iris darker

Abnormal iris lighter
  • Simple heterochromia — a rare condition characterized by the absence of other ocular or systemic problems. The lighter eye is typically regarded as the affected eye as it usually shows iris hypoplasia. It may affect an iris completely or only partially.
  • Congenital Horner's syndrome[9] — sometimes inherited, although usually acquired
  • Waardenburg's syndrome[9] — a syndrome in which heterochromia presents as a bilateral iris hypochromia in some cases. A Japanese review of 11 albino children with the disorder found that all had sectoral/partial heterochromia.[10]
  • 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.[11]
  • Incontinentia pigmenti[5]
  • Parry-Romberg syndrome[5]

Acquired heterochromia

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

A cat with heterochromia; It has one blue and one green eye
Abnormal iris darker
Abnormal iris lighter
  • Fuchs' heterochromic iridocyclitis — a condition characterized by a low grade, asymptomatic uveitis in 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 irises. It is often most easily seen in daylight. The prevalence of heterochromia associated with Fuch's has been estimated in various studies[12][13][14] with results suggesting that there is more difficulty recognizing iris color changes in dark-eyed individuals.[14][15]
  • Acquired Horner's syndrome — usually acquired, as in neuroblastoma,[16] 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.

Heterochromia has also been observed in those with Duane syndrome.[17][18]

Central heterochromia

A grey-blue iris with a greenish-yellow ring showing Central Heterochromia
File:EyewithCH.jpg
A Gray iris featuring Central Heterochromia

Whereas Heterochromia (also known as a heterochromia iridis or heterochromia iridium) is is an eye condition in which one iris is a different color from the other (complete heterochromia), Central Heterochromia (also known as Sectoral Heterochromia) is an eye condition in which there are two different colors in the same iris. Central Heterochromia is where the central (pupillary) zone of the iris is a different color than the mid-peripheral (ciliary) zone, and may be linked to above average toxic burden in the body.[19] In Central Heterochromia both eyes feature a central ring, usually brown/orange/yellow, and a true colored outer ring, The highly pigmented area that appears around the pupil and spreads outwards towards the edge of the iris may not be relevant to iris analysis unless it spills over the collarette. Conditions of gastric sub-acidity and hypochlorhydria may also be indicated. A common sign found in the biliary constitution.[20] Though not studied widely, Central Heterochromia is the rarest form of Heterochromia.[citation needed]

Eye color is determined primarily by the concentration and distribution of melanin pigment within the iris tissues, Anything affecting those factors may result in a difference of color being observed.[21]

The human iris can be seen in a number of various colors. There are three true colors in the eyes that determine the outward appearance; brown, yellow, and gray. How much of each color an individual has determines the appearance of his or her eye color.[22]

Eyes displaying Central Heterochromia are often referred to as "cat eyes" because of the appearance of a multi-colored iris. Central Heterochromia appears to be prevalent in irises containing low amounts of melanin[19][20].Central Heterochromia does not label an eye as hazel. This is because the outer ring of an eye affected by Central Heterochromia is that iris' true color.

The potential to acquire central heterochromia may be inherited genetically, though Central Heterochromia in itself is the condition where drug and toxic settlements in the body make the iris color appear different from its basic predominant color. These toxic signs that show in the iris indicate the amounts of the toxins the system has failed to eliminate.[20]

See also

References

  1. ^ Imesch PD, Wallow IH, Albert DM. "The color of the human eye: a review of morphologic correlates and of some conditions that affect iridial pigmentation." Surv Ophthalmol. 1997 Feb;41 Suppl 2:S117-23. PMID 9154287.
  2. ^ Wielgus AR, Sarna T. "Melanin in human irides of different color and age of donors." Pigment Cell Res. 2005 Dec;18(6):454-64. PMID 16280011.
  3. ^ Prota G, Hu DN, Vincensi MR, McCormick SA, Napolitano A. "Characterization of melanins in human irides and cultured uveal melanocytes from eyes of different colors." Exp Eye Res. 1998 Sep;67(3):293-9. PMID 9778410.
  4. ^ "All About Eye Color" from Larry Bickford
  5. ^ a b c d e f g h i Loewenstein, John; Scott Lee (2004). Ophthalmology: Just the Facts. New York: McGraw-Hill. ISBN 0-07-140332-9.
  6. ^ Misk NA, Semieka MA, Fathy A. "Heterochromia iridis in water buffaloes (Bubalus bubalis)." Vet Ophthalmol. 1998;1(4):195-201. PMID 11397231.
  7. ^ Swann P. "Heterochromia." Optometry Today. January 29, 1999. Accessed November 1, 2006.
  8. ^ van Emelen C, Goethals M, Dralands L, Casteels I. "Treatment of glaucoma in children with Sturge-Weber syndrome." J Pediatr Ophthalmol Strabismus. 2000 Jan-Feb;37(1):29-34. PMID 10714693.
  9. ^ a b Wallis DH, Granet DB, Levi L. "When the darker eye has the smaller pupil." J AAPOS. 2003 Jun;7(3):215-6. PMID 12825064.
  10. ^ Ohno N, Kiyosawa M, Mori H, Wang WF, Takase H, Mochizuki M. "Clinical findings in Japanese patients with Waardenburg syndrome type 2." Jpn J Ophthalmol. 2003 Jan-Feb;47(1):77-84. PMID: 12586183.
  11. ^ Brazel SM, Sullivan TJ, Thorner PS, Clarke MP, Hunter WS, Morin JD. "Iris sector heterochromia as a marker for neural crest disease." Arch Ophthalmol. 1992 Feb;110(2):233-5. PMID 1736874
  12. ^ Yang P, Fang W, Jin H, Li B, Chen X, Kijlstra A. "Clinical features of Chinese patients with Fuchs' syndrome." Ophthalmology. 2006 Mar;113(3):473-80. Epub 2006 Feb 3. PMID 16458965.
  13. ^ Arellanes-Garcia L, del Carmen Preciado-Delgadillo M, Recillas-Gispert C. "Fuchs' heterochromic iridocyclitis: clinical manifestations in dark-eyed Mexican patients." Ocul Immunol Inflamm. 2002 Jun;10(2):125-31. PMID 12778348.
  14. ^ a b Tabbut BR, Tessler HH, Williams D. "Fuchs' heterochromic iridocyclitis in blacks." Arch Ophthalmol. 1988 Dec;106(12):1688-90. PMID 3196209.
  15. ^ Bloch-Michel E. "[Fuchs heterochromic cyclitis: current concepts.]" J Fr Ophtalmol. 1983;6(10):853-8. PMID 6368659.
  16. ^ Mehta K, Haller JO, Legasto AC. "Imaging neuroblastoma in children." Crit Rev Comput Tomogr. 2003;44(1):47-61. PMID 12627783.
  17. ^ Khan AO, Aldamesh M. "Bilateral Duane syndrome and bilateral aniridia." J AAPOS. 2006 Jun;10(3):273-4. PMID 16814183.
  18. ^ Shauly Y, Weissman A, Meyer E. "Ocular and systemic characteristics of Duane syndrome." J Pediatr Ophthalmol Strabismus. 1993 May-Jun;30(3):178-83. PMID 8350229.
  19. ^ a b Key Ocular Signs for Screening
  20. ^ a b c Iris Color & Iris Pigmentation
  21. ^ Wielgus AR, Sarna T. "Melanin in human irides of different color and age of donors." Pigment Cell Res. 2005 Dec;18(6):454-64
  22. ^ Seddon JM, Sahagian CR, Glynn RJ, Sperduto RD, Gragoudas ES. "Evaluation of an iris color classification system." The Eye Disorders Case-Control Study Group. Invest Ophthalmol Vis Sci. 1990 Aug;31(8):1592-8. PMID: 2201662
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