Coloboma

What is a coloboma?

Coloboma refers to rare conditions in which normal tissue in or around the eye is missing. It may affect the eyelid, lens, macula, retina, optic nerve, or uvea (including the iris and pupil). A coloboma may also be found along with other conditions, such as:

• Heterochromia: different color in each eye
• Microphthalmia: small eyes
• Thickened corneas
• Cataracts: clouding of the eye lens
• Glaucoma: high pressure inside the eye
• Retinal dysplasia: an abnormality of the retina
• Nearsightedness or farsightedness
• Nystagmus: involuntary eye movements
• Posterior staphyloma: a protrusion at the back of the eyeball
• Certain genetic syndromes

What causes a coloboma?

A coloboma develops when eye development in a fetus is interrupted during the first two months of the pregnancy. While coloboma can be genetic, in other cases there is no known cause. There may be links between some environmental factors and coloboma, such as exposure of a fetus to alcohol during pregnancy.

What are the symptoms of a coloboma?

Whether or not a coloboma produces symptoms depends on where it is and how much tissue is missing.

• People who have macular or optic nerve coloboma may experience reduced vision.
• Those with retinal coloboma have a field defect, meaning they are missing vision in a specific location affected by the missing tissue.
• A coloboma in the front of the eye may not cause any vision problems, but some people report increased sensitivity to light.

How is a coloboma diagnosed?

An ophthalmologist can diagnose coloboma during a thorough eye examination with dilation. Genetic testing can be done in cases where a coloboma is associated with a specific genetic syndrome.

Is it possible to treat a coloboma?

There is no medication or surgical procedure that can cure or repair a coloboma, but there are steps patients can take to adjust to any vision problems and maximize the vision they have:

• Wearing glasses or contact lenses to correct vision
• Using colored contacts for two differently colored eyes
• Patching or putting blurring drops into a stronger eye to strengthen vision in a weaker eye
• Using low vision devices and vision rehabilitation services
• Treating lazy eye or microphthalmia in children
• Treating co-existing eye disorders, such as cataracts, glaucoma, and retinal detachment

Source: The National Eye Institute (NEI)

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