Editing Coloboma (section)

{{short description|Hole in one of the structures of the eye}}
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| image           = Coloboma of the iris.JPG
| caption         = Coloboma in a 16-year-old female
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A '''coloboma''' (from the Greek {{lang|grc|[[wikt:κολόβωμα|κολόβωμα]]}}, meaning "defect")<ref>{{cite encyclopedia| title= coloboma| encyclopedia= [[Mosby's Medical, Nursing & Allied Health Dictionary]] |edition= 4th |publisher= Mosby Year-Book| year= 1994| page= 361 | isbn= 9780801672255}}</ref> is a hole in one of the structures of the [[human eye|eye]], such as the [[iris (anatomy)|iris]], [[retina]], [[choroid]], or [[optic disc]]. The hole is present from birth and can be caused when a gap called the [[Choroidal fissure|choroid fissure]], which is present during early stages of prenatal development, fails to close up completely before a child is born. Ocular coloboma is relatively uncommon, affecting less than one in every 10,000 births.

The classical description in medical literature is of a [[keyhole]]-shaped defect. A coloboma can occur in one eye (unilateral) or both eyes (bilateral). Most cases of coloboma affect only the iris. The level of vision impairment of those with a coloboma can range from having no vision problems to being able to see only light or dark, depending on the position and extent of the coloboma (or colobomata if more than one is present).