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Merck Manual

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Eye Defects


Simeon A. Boyadjiev Boyd

, MD, University of California, Davis

Last full review/revision May 2020| Content last modified May 2020
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Eyes can be missing, deformed, or incompletely developed at birth.

Birth defects of the eye include the following:

  • Hypertelorism: Widely spaced eyes, can occur in several congenital syndromes (a group of defects present at birth that occur together)

  • Hypotelorism: Closely spaced eyes

  • Coloboma: A missing piece of tissue in any part of the eye, such as the eyelid, iris, retina, or optic nerve of one or both eyes

  • Microphthalmia: A small eyeball (may affect one or both eyes)

  • Anophthalmia: Complete absence of the eyeball (can occur in more than 50 congenital syndromes)

Some of these birth defects may be caused by mutations in certain genes. Others may be caused by the mother's use of certain drugs or alcohol while pregnant or an infection she may have had while pregnant.

Before birth, doctors may be able to identify some eye defects during an ultrasound and sometimes by taking a sample of blood to do genetic testing.

After birth, doctors can identify many eye defects during a physical examination.

Examples of Birth Defects of the Eyes
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