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What is aniridia?

Very rarely before a baby is born, not all of the eye develops as it should. If the iris does not grow then this is known as aniridia. In some children only some parts of the iris is affected and the condition is called ‘partial’ aniridia.

Image of a child with aniridia and one with partial aniridia

What is the cause of aniridia?

The condition may run in families. A child can inherit aniridia from a parent who also has the condition. It can also occur randomly in some cases.

It can also happen because of injury or eye surgery complications.

How is it diagnosed?

Aniridia can be diagnosed during an examination by an ophthalmologist. Using a special piece of equipment called a slit lamp. The ophthalmologist uses this to see the parts of the iris that are missing.

How does aniridia affect the way a child sees?

Most young children will feel their vision to be ‘normal’ as they have never known anything else.

Aniridia can affect vision in different ways depending on the level to which the iris is affected and if there are other problems with the eyes. It can affect one or both eyes.

If a large part of the iris is missing then the sharpness of vision may be reduced. This is because the normal iris and pupil reduce the amount of light entering the eye and help the lens to focus light to the back of the eye (retina). Without an iris too much light gets into the eye, this can cause glare specially on sunny days.

Sometimes children with aniridia can develop fast ‘to and fro’ shaking movements of the eyes called nystagmus, this can also reduce sharpness of vision. Vision can often be improved by wearing glasses that focus the light more sharply on to the back of the eye. Adding a tint to the lenses can reduce glare.

Useful contacts

The Orthoptic Department at Sheffield Children’s Hospital

0114 271 7468 or 0114 2717481

Sheffield Royal Society for the Blind

Advice and support for children of all ages with a vision problem
5 Mappin Street, Sheffield, S1 4DT
0114 272 2757

Sheffield Specialist Support Services and Visually Impaired Service

Advice and support for children of all ages with a vision problem
0114 239 8336


0845 766 9999

LOOK (For families with visually impaired children)

0121 428 5038

Tadpoles (International Glaucoma Association)

108c Warner Road, London, SE5 9HQ
020 7737 3265


PO Box 118, Westerham, TN16 3WR
01959 570142

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Please note: this is a generic information sheet relating to care at Sheffield Children’s NHS FT. These details may not reflect treatment at other hospitals. This information is not intended as a substitute for professional medical care. Always follow your healthcare professionals’ instructions. If this resource relates to medicines, please read it alongside the medicine manufacturer’s patient information leaflet. If this information has been translated into another language from English, efforts have been made to maintain accuracy, but there may still be some translation errors. If you are unsure about any of the guidance in this resource or have specific questions about how it relates to your child, always ask your healthcare professional for further advice.

Resource number: EYE14

Resource Type: Article

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