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A coloboma (from the Greek koloboma, meaning defect,^[1]) is a hole in one of the structures of the eye, such as the iris, retina, choroid, or optic disc. The hole is present from birth and can be caused when a gap called the choroid fissure, which is present during early stages of prenatal development, fails to close up completely before a child is born. The classical description in medical literature is of a key-hole shaped defect. A coloboma can occur in one eye (unilateral) or both eyes (bilateral). Most cases of coloboma affect only the iris. People with coloboma may have no vision problems or may be blind, depending on severity. It affects less than one in every 10,000 births.

Signs and symptoms

The effects a coloboma has on the vision can be mild or more severe depending on the size and location of the gap. If, for example, only a small part of the iris is missing, vision may be normal, whereas if a large part of the retina or optic nerve is missing, vision may be poor and a large part of the visual field may be missing. This is more likely to cause problems with mobility if the lower visual field is absent. Other conditions can be associated with a coloboma. Sometimes, the eye may be reduced in size, a condition called microphthalmia, or glaucoma, nystagmus, scotoma, or strabismus may occur.

Causes

Colobomas can be associated with a mutation in the PAX2 gene.^[2]

Eye abnormalities having been shown to occur in over 90% of children with the Fetal alcohol syndrome.^[3]

Related conditions

Other ocular malformations that include coloboma or are related to it:

CHARGE syndrome, a term that came into use as an acronym for the set of unusual congenital features seen in a number of newborn children.^[4] The letters stand for: coloboma of the eye, heart defects, atresia of the nasal choanae, retardation of growth and/or development, genital and/or urinary abnormalities, and ear abnormalities and deafness. Although these features are no longer used in making a diagnosis, the name has remained.
Cat eye syndrome, caused by the short arm (p) and a small section of the long arm (q) of human chromosome 22 being present three (trisomic) or four times (tetrasomic) instead of the usual two times. The term "cat eye" was coined because of the particular appearance of the vertical colobomas in the eyes of some patients.
Patau syndrome (trisomy 13), a chromosomal abnormality that can cause a number of deformities, some of which include structural eye defects, including microphthalmia, Peters anomaly, cataract, iris and/or fundus coloboma, retinal dysplasia or retinal detachment, sensory nystagmus, cortical visual loss, and optic nerve hypoplasia.
Treacher Collins syndrome, autosomal dominant syndrome caused by mutation of TCOF1. Coloboma is part of a set of characteristic facies that features craniofacial malformations, such as downslanting eyes, ear anomalies, or hypoplasia of zigomatic bone and jaw (micrognathia).

Epidemiology

The number of cases is around 0.5 to 0.7 per 10,000 births, making it a relatively rare condition.^[5]

Treatment

No treatment is available for the visual impairment caused by coloboma at present. Specialized contact lenses can be used later in life for colobomas of the iris, and glasses can be used to help with vision problems.^[6]

Notable cases

Perhaps the most famous people with coloboma are John Ritter, Henry Cavill, New York Times columnist Andrew Ross Sorkin, tennis player Arnaud Clément, alternative rock singer songwriter Lachi, wecfbweas and Madeleine McCann. McCann, a British girl, disappeared from the holiday apartment rented by her parents in May 2007 just before her fourth birthday. Posters and online campaigns promoting the search for Madeleine use the word "Look" with the first "O" in the word being drawn in the shape of a coloboma radius extending from the pupil at the 7 o'clock position.

References

^ coloboma, Mosby's Medical, Nursing & Allied Health Dictionary, Fourth Edition, Mosby Year-Book, 1994, p. 361
^ Cunliffe HE, McNoe LA, Ward TA, Devriendt K, Brunner HG, Eccles MR (October 1998). "The prevalence of PAX2 mutations in patients with isolated colobomas or colobomas associated with urogenital anomalies". J. Med. Genet. 35 (10): 806–12. doi:10.1136/jmg.35.10.806. PMC 1051454. PMID 9783702.
^ "Eye abnormalities in fetal alcohol syndrome.". Ulster Med J 78: 164–5. Sep 2009. PMC 2773598. PMID 19907681.
^ Pagon RA, Graham JM, Zonana J, Yong SL (1981). "Coloboma, congenital heart disease, and choanal atresia with multiple anomalies: CHARGE association". J. Pediatr. 99 (2): 223–7. doi:10.1016/S0022-3476(81)80454-4. PMID 6166737.
^ Hornby, SJ; Adolph, S; Gilbert, CE; Dandona, L; Foster, A (Mar 2000). "Visual acuity in children with coloboma: clinical features and a new phenotypic classification system.". Ophthalmology 107 (3): 511–20. doi:10.1016/S0161-6420(99)00140-2. PMID 10711890.
^ RNIB database - Supporting blind and partially sighted people - Coloboma; http://www.rnib.org.uk/eye-health-eye-conditions-z-eye-conditions/coloboma#P92_9303

External links

Micro & Anophthalmic Children's Society

UpToDate Contents

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English Journal

First implication of STRA6 mutations in isolated anophthalmia, microphthalmia, and coloboma: A new dimension to the STRA6 phenotype.

Casey J, Kawaguchi R, Morrissey M, Sun H, McGettigan P, Nielsen JE, Conroy J, Regan R, Kenny E, Cormican P, Morris DW, Tormey P, Ní Chróinín M, Kennedy BN, Lynch S, Green A, Ennis S.SourceSchool of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland.
Human mutation.Hum Mutat.2011 Dec;32(12):1417-26. doi: 10.1002/humu.21590. Epub 2011 Sep 29.
Microphthalmia, anophthalmia, and coloboma (MAC) are structural congenital eye malformations that cause a significant proportion of childhood visual impairments. Several disease genes have been identified but do not account for all MAC cases, suggesting that additional risk loci exist. We used singl
PMID 21901792

Anophthalmos, Microphthalmos, and Coloboma in the United Kingdom: Clinical Features, Results of Investigations, and Early Management.

Shah SP, Taylor AE, Sowden JC, Ragge N, Russell-Eggitt I, Rahi JS, Gilbert CE; Surveillance of Eye Anomalies Special Interest Group*.SourceInternational Centre for Eye Health, London School of Hygiene and Tropical Medicine, London, United Kingdom; Medical Research Council Centre of Epidemiology for Child Health, Institute of Child Health, University College London, United Kingdom.
Ophthalmology.Ophthalmology.2011 Nov 4. [Epub ahead of print]
PURPOSE: To describe the clinical features of children with anophthalmos, microphthalmos, and typical coloboma (AMC).DESIGN: Descriptive, observational, cross-sectional study of the United Kingdom.PARTICIPANTS: A total of 135 children with AMC newly diagnosed over an 18-month period beginning in Oct
PMID 22054996

Japanese Journal

水晶体欠損と第一次硝子体過形成遺残を合併した朝顔症候群の1例 (特集第67回日本臨床眼科学会講演集(7))

三根正,平田憲
臨床眼科 68(9), 1325-1328, 2014-09
NAID 40020190741

Endocrinological Characteristics of 25 Japanese Patients with CHARGE Syndrome

Shoji Yasuko,Ida Shinobu,Etani Yuri,Yamada Hiroyuki,Kayatani Futoshi,Suzuki Yasuhiro,Kosaki Kenjiro,Okamoto Nobuhiko
Clinical Pediatric Endocrinology 23(2), 45-51, 2014
… CHARGE syndrome is a congenital disorder caused by mutation of the chromodomain helicase DNA binding protein 7 (CHD7) gene and is characterized by multiple anomalies including ocular coloboma, heart defects, choanal atresia, retarded growth and development, genital and/or urological abnormalities, ear anomalies, and hearing loss. …
NAID 130004853599

症例先天性上眼瞼欠損に対してmyotarsocutaneous flap変法を用いて再建を行った2例

小久保健一,嘉鳥信忠,林憲吾 [他]
形成外科 56(10), 1103-1107, 2013-10
NAID 40019815017

Related Pictures

★リンクテーブル★

リンク元	「コロボーマ」「眼欠損症」
拡張検索	「renal coloboma syndrome」

「コロボーマ」

Coloboma
Classification and external resources
Specialty	medical genetics
ICD-10	Q10.3, Q12.2, Q13.0, Q14.2, Q14.8
ICD-9-CM	377.23, 743.4, 743.46, 743.52, 743.57
DiseasesDB	29894
MedlinePlus	003318
Patient UK	Coloboma
MeSH	D003103