Aniridia

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.

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.