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Aniridia – Symptoms, Diagnosis and Treatment
Medically reviewed by Sharon Copeland on 29 June 2022
Aniridia (or isolated aniridia) is when part or all of the iris (coloured part of the eye) is missing from the eye. This condition causes the eye to look darker as the coloured part of the eye isn’t as visible.
What is aniridia of the eye?
The word “aniridia” means “no iris”, but the amount of iris tissue missing will vary from person to person. People with this condition often have very large pupils (the hole in the middle of each iris), which may also have an irregular shape because so much of their iris tissue is missing. Some people with aniridia may have more regular looking iris and the changes are only visible to an optician or Ophthalmologist.
Over 280 mutations in the PAX6 gene can lead to aniridia, which occurs while the eye is developing during the 12th to 14th week of pregnancy. In most cases, it is due to a mutation in the short arm of chromosome 11 (11p13) and affects the PAX6 gene, PAX6 gene provides instructions for making a protein that is involved in the early development of the eyes, brain, spinal cord, and pancreas.
In dark conditions, the iris lets the pupil expand to let in more light. In bright conditions, the iris causes the pupil to shrink, allowing less light in. Due to the iris’s role in controlling how much light passes through the eye, those with aniridia can develop light sensitivity (photophobia).
Can you see with aniridia?
People with this condition may have issues with visual acuity as this condition doesn’t allow the eye to control light in the way it needs to. Without the right level of light control, there can be too much light to see clearly.
Those affected may experience dazzle, particularly in bright conditions, or difficulty adjusting, as light levels change, reducing vision. As well as having an impact on sight, the light sensitivity (photophobia) they experience can cause discomfort and can, for some people, cause headaches.
Aniridia nearly always causes other parts of the eye to be underdeveloped, such as the optic nerve and fovea, and can also cause nystagmus (involuntary movement of the eye). These conditions can also affect vision in addition to the lack of iris. People with aniridia may also develop other eye disorders, such as glaucoma, cataract and corneal problems; these effects on the eye can have a larger impact on sight than the large pupil or lack of iris itself. Affected individuals have quite a lot of sight loss, others may have only mild blurred vision.
How is aniridia diagnosed?
Aniridia is rare and often diagnosed in infancy. The condition is usually noticeable, as the baby’s eye will be darker. As the child grows, this condition can cause visual development issues.
What symptoms does aniridia cause?
This condition can cause several eye problems, such as:
- Blurred vision
- Partial blindness
- Discomfort or pain in the eye
- Flashes of light
What causes aniridia ?
Aniridia can also be inherited, develop after trauma to the eye or an eye infection. Those who develop this condition from birth may need to wear contact lenses or glasses, their eyes will need to be monitored regularly by an optician to ensure the condition doesn’t progress into an unmanageable state.
How can I manage aniridia?
Patients with aniridia can sometimes see improved vision through treatment, this can be done several ways:
- Coloured contact lenses can help change the cosmetic appearance of the eye and help minimise glare
- Rehabilitation devices and training can be provided
- Tinted glasses and hats to minimise glare
Treatment is usually directed at improving and preserving vision. Drugs or surgery may be helpful for glaucoma and/or cataracts. Contact lenses may be beneficial in some cases.