Heterocromia de íris: uma revisão das condições que podem afetar a pigmentação iridiana / Heterochromia: a review of conditions that may affect iris pigmentation

RESUMO A íris é responsável pela cor dos olhos. Ela ainda realiza o controle da quantidade de luz que penetra no olho pela pupila. Variações nos genes de cada indivíduo, além da quantidade e da qualidade de melanina na íris, determinam a cor dos olhos. A heterocromia é caracterizada por diferenças na coloração da íris de um mesmo indivíduo, sendo, na maioria das vezes, benigna. Existem basicamente três tipos de heterocromia de íris: central, setorial e completa. A heterocromia de íris pode ter como causa alterações genéticas e congênitas, relacionadas ou não a síndromes específicas, como a de Sturge-Weber, a de Waardenburg, a de Parry-Romberg e a de Horner congênita. Há também causas adquiridas, como doenças ou lesões, trauma ocular e corpos estranhos intraoculares, uso de certas medicações tópicas, siderose ocular, irites ou uveítes como a síndrome uveítica de Fuchs, dentre outras. Diante de um paciente com heterocromia de íris, deve-se entender o contexto e o curso clínico desse sinal, pois pode se tratar de uma alteração de pigmentação benigna ou existir uma doença base em curso, que requer terapêutica específica. Este artigo de revisão de literatura visa abordar as principais etiologias relacionadas à heterocromia de íris, além de discorrer sobre a anatomia e a fisiologia da coloração iridiana e sobre a fisiopatologia de suas possíveis alterações.

ABSTRACT The iris is responsible for eye color and controls the amount of light that enters the eye through the pupil. Variation in each individual's genes, besides the quantity and quality of melanin in the iris, determine eye color. Heterochromia is characterized by different colors of irises in the same individual, and it is benign in most cases. There are basically three types of heterochromia: central, partial and complete. Heterochromia can be caused by genetic and congenital alterations, which may or may not be related to specific conditions, such as Sturge-Weber syndrome, Waardenburg syndrome, Parry-Romberg syndrome and congenital Horner syndrome. It may be associated to acquired causes like diseases or injuries, such as eye trauma and intraocular foreign bodies, use of some topical medications, ocular siderosis, iritis or uveitis, such as Fuchs´ uveitis, among others. When assessing a patient with heterochromia, one must understand the context and clinical course of this signal, since it may be a benign pigmentation disorder or there may be an underlying disease, which requires specific therapy. This literature review article was set out to address the main etiologies related to heterochromia, in addition to describing the anatomy and physiology of the iris color and the pathophysiology of possible alterations.

Bilateral asymmetrical partial heterochromia of iris and fundus in Waardenburg syndrome type 2A with a novel MITF gene mutation

A 3-year-old girl presented with bilateral asymmetrical partial heterochromia of iris and fundus. The parents also complained of bilateral hearing loss in the child. Suspecting an auditory-pigmentary syndrome, systemic and genetic evaluation was performed. The child had profound sensory-neural hearing loss. Targeted gene sequencing revealed a novel nonsense variation in exon 9 of the MITF gene (chr3:70008440A>T) that was pathogenic for Waardenburg syndrome (WS) type 2A. This case highlights the characteristics of the iris and fundus hypochromia, which may provide a clue toward the diagnosis of WS.

Ocular Coloboma Associated with Iris Heterochromia: A Case Report.

Coloboma of the eyelids, lens, iris, ciliary body, choroid, retina and/or optic nerve arise from failed or incomplete closure of the embryonic fi ssure during development. A ocular colobomas may extend from the pupillary frill of the iris anteriorly to the optic disc posteriorly. Th e ocular colobomata may be associated with many systemic and ocular congenital anomalies. A coloboma can occur in one eye (unilateral) or both eyes (bilateral). People with coloboma may have no vision problems or may be blind, depending on severity. We report a case of unilateral typical coloboma of the iris, retina, and choroid associated with heterochromia of the iris.

Congenital Horner Syndrome with Heterochromia Iridis Associated with Ipsilateral Internal Carotid Artery Hypoplasia

BACKGROUND: Horner syndrome (HS), also known as Claude-Bernard-Horner syndrome or oculosympathetic palsy, comprises ipsilateral ptosis, miosis, and facial anhidrosis. CASE REPORT: We report herein the case of a 67-year-old man who presented with congenital HS associated with ipsilateral hypoplasia of the internal carotid artery (ICA), as revealed by heterochromia iridis and confirmed by computed tomography (CT). CONCLUSIONS: CT evaluation of the skull base is essential to establish this diagnosis and distinguish aplasia from agenesis/hypoplasia (by the absence or hypoplasia of the carotid canal) or from acquired ICA obstruction as demonstrated by angiographic CT.

Waardenburg syndrome: A rare genetic disorder, a report of two cases.

Waardenburg syndrome (WS) is a rare genetic disorder. Patients have heterochromia or eyes with iris of different color, increased inter-canthal distance, distopia canthorum, pigmentation anomalies, and varying degree of deafness. It usually follows autosomal dominant pattern. In this report, two cases have been discussed but no familial history of WS has been found. Counseling of the patient is necessary and cases of irreversible deafness have been treated.

Heterochromia in rabbit-heterochromia in a dutch pigmented rabbit / 国际眼科杂志(Guoji Yanke Zazhi)

· Heterochromia was observed in a six-month-old Dutch pigmented rabbit and the rabbit was examined for general and eye anomalies. The rabbit showed a blue eye with fundus hypochromia on the right and a brown eye with partial fundus hypochromia on the left. White fur (white forelock) was present, but deafness was not apparent although no objective audiologic examination was performed. Histology studies of both eyes revealed that significantly fewer pigment cells in iris stroma and less pigmentation in retinal pigment epithelium and choroid in the right eye than in the left eye.

Three Cases of Waardenburg Syndrome Type 2 in a Korean Family

Waardenburg syndrome (WS) is a rare, autosomal dominant disorder characterized by sensorineural hearing loss, pigmentary disturbances of the skin, hair, and iris, and other developmental defects such as lateral displacement of both medial canthi and lacrimal puncta called dystopia canthorum. While mutations of the PAX3 (paired box) gene have been identified in about 99% of WS type 1 cases, WS type 2 is a heterogeneous group, with about 15% of cases caused by mutations in microphthalmia associated transcription factor (MITF). We have experienced three cases of typical WS type 2 in a Korean family, for whom full ocular examination and genetic studies were performed. The genetic studies revealed no mutation in either PAX3 or MITF genes. The genetic basis, as yet unknown for most cases of WS type 2, might be found with further investigation.

A Case of Acquired Transient Heterochromia of the Scalp Hair / 대한피부과학회지

Heterochromia is the presence of more than one distinct color of hair in a person. It is known to be related with genetic background, but definite cause of this disorder has not been found. Several cases of heterochromia of the scalp hair have been reported and each case has different pattern, distribution and course. We report a 6-month-old infant with acquired transient heterochromia of the scalp hair who has unusual pattern and course different from previously reported case.