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Iris hypoplasia

What is the iris?

The iris is the part of the eye we refer to when we say a person has, green, blue, brown or grey eyes. It is a small circular muscle with a hole in the middle, called the pupil. The iris controls the amount of light that enters the eye by contracting in bright light making the pupil small and dilating in dark conditions making the pupil large.

What is Iris hypoplasia?

Hypoplasia is a medical term for underdevelopment therefore iris hypoplasia means underdevelopment of the iris.

It may occur either...

BILATERALLY: Affecting both eyes. In aniridia iris hypoplasia is almost always bilateral.

UNILATERALLY: Affecting one eye only.

There are also different degrees of iris hypoplasia

TOTAL ANIRIDIA: No visible iris in one or both eyes.
TOTAL: No visible iris in one or both eyes. A person with totally absent irises appears to have very dark eyes this is because they only have a large pupil. However, the iris is never completely absent; the root of the iris is still present but the muscle which creates the visible iris is missing.

PARTIAL ANIRIDIA: Part of one or both Irises is missing.
A person with partially absent irises appear to have very large and/or misshapen pupils with a small ring of colour arround the edge of the pupil. in these cases the iris will not contract and dilate when appropriate.

ATYPICAL ANIRIDIA: The iris may appear normal but it may be thinner than normal or have Slit like iris stromal (connective tissue) defects. Ectopia pupillae may be a form of atypical aniridia.

Sometimes atypical aniridia may be misdiagnosed as a number of similar eye conditions such as

Riegers Anomaly/Syndrome

Iris Coloboma

How does it affect a person?

As the iris regulates the amount of light that can enter the eye, an eye with little or no iris allows in more light than a normal eye. This causes photophobia which is a difficulty to see due to glare and discomfort in bright light conditions.

The iris also plays a small part in focusing light on the back of the retina. However, the absence of this function does not cause significant visual impairment.

Another affect of this aspect of aniridia is that the dilating and contracting irises are part of body language. However, people with dark or absent irises can be seen a mysterious and beautiful. Those with some iris may find people make comments on their unusual shaped irises. If this becomes a problem contact lenses may help improve the eyes appearance.

Is there any treatment

There is no treatment that will replace the full function of the iris. However, there are treatments that mimic a static iris, which can help with photophobia and the appearance of the iris. See below for more details.

contact lenses

iris tattoo