Heterochromia iridum
Heterochromia | |
---|---|
Complete heterochromia iridum | |
Specialty | Ophthalmology |
Symptoms | Different or partially different eye color |
Duration | Lifelong |
Treatment | Iris implant surgery (controversial for cosmetic purposes) |
Heterochromia is a variation in
It occurs in humans and certain breeds of domesticated animals.Heterochromia of the eye is called heterochromia iridum or heterochromia iridis. It can be complete, sectoral, or central. In complete heterochromia, one iris is a different color from the other. In sectoral heterochromia, part of one iris is a different color from its remainder. In central heterochromia, there is a ring around the pupil or possibly spikes of different colors radiating from the pupil.
Though multiple causes have been posited, the scientific consensus is that a lack of genetic diversity is the primary reason behind heterochromia, at least in domestic animals. This is due to a mutation of the genes that determine melanin distribution at the 8-HTP pathway, which usually only become corrupted due to chromosomal homogeneity.[3] Though common in some breeds of cats, dogs, cattle and horses due to inbreeding, heterochromia is uncommon in humans, affecting fewer than 200,000 people in the United States, and is not associated with lack of genetic diversity.[4][5]
The affected eye may be hyperpigmented (hyperchromic) or hypopigmented (hypochromic).[3] In humans, an increase of melanin production in the eyes indicates hyperplasia of the iris tissues, whereas a lack of melanin indicates hypoplasia.
The term is derived from Ancient Greek: ἕτερος, héteros "different" and χρῶμα, chrôma "color".[6]
Background
The color of the mammalian, including human, iris is very variable. However, there are only two pigments present,
Classification
Heterochromia is classified primarily by onset: as either
Genetic
Abnormal iris darker
- Lisch nodules – iris hamartomas seen in neurofibromatosis.
- episclera, and anterior chamber angle.
- Oculodermal melanocytosis (nevus of Ota)[3]
- 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.[medical citation needed]
- ipsilateral leptomeningeal angiomas with intracranial calcification and neurologic signs, and angioma of the choroid, often with secondary glaucoma.[14][15]
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[16] – sometimes inherited, although usually acquired.
- Waardenburg syndrome[16] – a syndrome in which heterochromia is expressed as a bilateral iris hypochromia in some cases. A Japanese review of 11 children with albinism found that the condition was present. All had sectoral/partial heterochromia.[17]
- 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.[18]
- Incontinentia pigmenti[3]
- Parry–Romberg syndrome[3]
Acquired
Acquired heterochromia is usually due to injury, inflammation, the use of certain eyedrops that damage the iris,[19] 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.
- Certain eyedrops – prostaglandin analogues (latanoprost, isopropyl unoprostone, travoprost, and bimatoprost) are used topically to lower intraocular pressure in glaucoma patients. A concentric heterochromia has developed in some patients applying these drugs. The stroma around the iris sphincter muscle becomes darker than the peripheral stroma.[medical citation needed] A stimulation of melanin synthesis within iris melanocytes has been postulated.[20]
- Neoplasm – Nevi and melanomatous tumors.
- Iridocorneal endothelium syndrome[3]
- Iris ectropion syndrome[3][21]
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 irides. It is often most easily seen in daylight. The prevalence of heterochromia associated with Fuchs has been estimated in various studies[22][23][24] with results suggesting that there is more difficulty recognizing iris color changes in dark-eyed individuals.[24][25]
- Acquired Horner's syndrome – usually acquired, as in neuroblastoma,[26] 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.
- Parry–Romberg syndrome – due to tissue loss.[27]
Heterochromia has also been observed in those with Duane syndrome.[28][29]
Partial heterochromia – different colors in the same iris
Partial heterochromia is most often a benign trait of genetic origins, but, like complete heterochromia, can be acquired or be related to clinical syndromes.
Sectoral
In sectoral heterochromia, areas of the same iris contain two different colors, the contrasting colors being demarcated in a radial, or sectoral, manner. Sectoral heterochromia may affect one or both eyes.[30] It is unknown how rare sectoral heterochromia is in humans, but it is considered to be less common than complete heterochromia.
Central
Central heterochromia is also an eye condition where there are two colors in the same iris; but the arrangement is concentric, rather than sectoral. The central (pupillary) zone of the iris is a different color than the mid-peripheral (ciliary) zone. Central heterochromia is more noticeable in irises containing low amounts of melanin.[31]
In history and culture
Heterochromia of the eye was first described as a human condition by Aristotle, who termed it heteroglaucos.[12]
Notable historical figures thought to have heterochromia include the
The Alexander Romance, an early literary treatment of the life of Alexander the Great, attributes heterochromia to him. In it he is described as having one eye light and one eye dark. However, no ancient historical source mentions this. It is used to emphasise the otherworldly and heroic qualities of Alexander.[36][37]
In the Ars Amatoria, the Roman poet Ovid describes the witch Dipsas as having 'double pupils'. Kirby Flower Smith suggested that this could be understood as heterochromia, though other scholars have disagreed. The Roman jurist and writer Cicero also mentions the same feature of 'double pupils' as being found in some Italic women. Pliny the Elder related this feature to the concept of 'the evil eye'.[38]
The twelfth-century scholar Eustathius, in his commentary on the Iliad, reports a tradition in which the Thracian Thamyris (son of the nymph Argiope), who was famed for his musical abilities, had one eye that was grey, whilst the other was black. W. B. McDaniel suggests that this should be interpreted as heterochromia.[39]
In other animals
Although infrequently seen in humans, complete heterochromia is more frequently observed in species of domesticated mammals. The blue eye occurs within a white spot, where melanin is absent from the skin and hair (see
Sectoral heterochromia, usually sectoral hypochromia, is often seen in
See also
References
- PMID 28417041.
- PMID 9154287.
- ^ ISBN 0-07-140332-9.
- doi:10.23649/jae.2017.2.3.1.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - PMID 18725617.
- ^ "heterochromia iridis - definition of heterochromia iridis in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia". Medical-dictionary.thefreedictionary.com. Retrieved 2014-04-27.
- PMID 16280011.
- PMID 9778410.
- ^ National Day Calendar "National Different Colored Eyes Day - July 12" Archived 2023-03-31 at the Wayback Machine National Day Calendar. November 8, 2022. Retrieved July 12, 2023.
- ^ Swann P. "Heterochromia." Archived 2006-01-08 at the Wayback Machine Optometry Today. January 29, 1999. Retrieved November 1, 2006.
- ^ "Heterochromia: MedlinePlus Medical Encyclopedia". Nlm.nih.gov. Retrieved 2014-04-27.
- ^ PMID 5797351.
- ^ Guha M, Maity D (2014). "Heterochromia iridis - a case study". Explor Anim Med Res. 4 (2): 240–245.
- PMID 10714693.
- ^ "Sturge-Weber syndrome: Definition and Much More from Answers.com". Answers.com<!. Retrieved 2009-11-19.
- ^ PMID 12825064.
- PMID 12586183.
- PMID 1736874.
- PMID 10660314.
- PMID 12204714.
- PMID 35593818.
- PMID 16458965.
- S2CID 21171244.
- ^ PMID 3196209.
- PMID 6368659.
- PMID 12627783.
- Genetic and Rare Diseases Information Center (GARD). "Heterochromia iridis".
- PMID 16814183.
- PMID 8350229.
- ^ "Heterochromia iridis". Genetic and Rare Diseases Information Center (GARD) – an NCATS Program. NIH. 8 April 2015. Retrieved 9 February 2019.
- PMID 26547379.
- JSTOR 44170668.
- S2CID 26240821.
- ^ Head, C. (1980)"PHYSICAL DESCRIPTIONS OF THE EMPERORS IN BYZANTINE HISTORICAL WRITING", Byzantion, Vol. 50, No. 1 (1980), pp. 226-24, Peeters Publishers, p. 229
- ISBN 978-1-412-84321-8.
- ISBN 9781443818117, p. 44
- ^ Boardman, J. (2019) Alexander the Great: From His Death to the Present Day, Princeton University Press, Princeton N.J., p. 40
- ^ Alvar Nuño, A. (2012) "Ocular Pathologies and the Evil Eye in the Early Roman Principate", Numen, Vol. 59, No. 4 (2012), pp. 295-321, pp. 299-301
- ^ McDaniel, W,B. (1918) "The Pupula Duplex and Other Tokens of an "Evil Eye" in the Light of Ophthalmology", Classical Philology, Vol. 13, No. 4 (Oct., 1918), pp. 335-346, The University of Chicago Press, p.338
- PMID 11397231.
- tertiary sourcereuses information from other sources but does not name them.
External links
- Media related to Heterochromia at Wikimedia Commons