Aniridia

What is aniridia?

Aniridia is a very rare eye condition in which the coloured part of the eye (the iris) does not fully develop, and which often leads to other associated eye problems. It affects both eyes and is a condition you're born with. 

What causes aniridia?

Aniridia is a condition you are born with due to a fault in one of your genes. Around 2 out of 3 people with aniridia inherit a faulty version of the gene PAX6 that has been passed down through the family. About 1 in 3 people have no family history of aniridia but develop a fault with PAX6 in the womb.

In a few cases (about 2 out of every 100 people with the condition), aniridia is linked to Gillespie syndrome, an inherited disorder which affects balance, movement, and mental ability.

What are the signs and symptoms of aniridia?

Aniridia causes eye and vision problems soon after birth, at around six weeks old. Most people with aniridia also have an under-developed fovea, which is a part of the light-sensitive layer of the eye (the retina) that we use for detailed colour vision - this can further affect eyesight.

Later in life, aniridia can lead to other eye problems such as glaucoma, cataract, and corneal opacification, where the cornea (the front surface of the eye) becomes cloudy. The lens in the eye is often cloudy, too. 

The early symptoms include:  

• Involuntary eye movements (nystagmus)
• Trouble focusing (refractive error)
• Eyes that point in different directions (strabismus)
• Drooping eyelids (ptosis)
• Light sensitivity (photophobia)
• The cornea may be painful
• Vision may be hazy or blurred and the field of view may become more narrow over time

Is aniridia serious?

Aniridia affects everyone differently, but will have at least some effect on vision, and for some people it can lead to sight loss if not managed properly. The main threats to sight come from glaucoma and from the lens and cornea becoming cloudy, reducing the amount of light reaching the retina.

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How is aniridia diagnosed?

Aniridia can be diagnosed through a clinical examination by an eye specialist, who will look for the signs and symptoms of the condition, such as a partially or fully absent iris, nystagmus, and related eye issues like cataracts or glaucoma.

Genetic testing can also be done to identify mutations in the PAX6 gene, confirming the diagnosis and helping to inform genetic counselling for the family.

What are the treatments for aniridia?

There is no cure for aniridia, although the right glasses or contact lenses may help with vision problems. There are treatments for some of the conditions that are linked to aniridia, such as include eye drops to reduce high pressure in the eye and prevent glaucoma from getting worse.

Treatment may also include a corneal transplant to reconstruct the front of the eye. If you also have cataracts, they may need to be treated with cataract surgery.

What can help aniridia?

Managing aniridia involves regular monitoring by an eye specialist to promptly address any developing complications. 

Low vision aids and protective eyewear such as sunglasses can also help people with aniridia manage their condition and improve their quality of life.

What research is there into aniridia?

Although we know the gene that causes aniridia, we still don’t understand exactly how the gene leads to disease and there are no specific treatments available yet. An important line of research is to find out why stem cells on the surface of the cornea stop working over time. It may be possible to develop a cell therapy that can keep the cornea clear.

See our research projects