What is aniridia?
Aniridia is an eye disease that is characterised by the total or partial loss of the iris, the contractile ring surrounding the pupil that gives our eyes their colour, as well as controlling the amount of light that enters the eyeball.
Although it can be an acquired disorder following an accident or other causes, it is generally a congenital disease that affects 1 in every 80,000 newborns. It is therefore considered “rare” or minority.
As well as a missing or rudimentary iris that has not fully developed, this eye disease also affects other parts of the eye in 90% of the cases, causing different vision problems through life.
Aniridia means that the eye’s pupil (central black hole) is seen larger than using or has an irregular shape.
The main symptoms associated to the disease are photophobia –due to the difficulties in controlling the entry of light due to the missing iris–, as well as blurred vision or poor visual acuity when it is associated, for example, to opacity of the cornea, a cataract, or poor development of the optic nerve or macula (central part of the retina). Aniridia is also commonly linked to glaucoma –present in half of all patients–, or to other problems such as nystagmus (involuntary movements with the eyes and consequence difficulty in focusing), a depletion of corneal epithelial stem cells, dry eye, amblyopia or strabismus.
Acquired aniridia is linked to external factors, normally severe eye injuries. Congenital aniridia is caused by a mutation of the PAX-6 gene that is involved in the formation of the eye during pregnancy. This mutation is generally hereditary and is transferred from parents to children in an autosomal dominant pattern, so only one of the two parents has to be a carrier of the defective gene for the child to suffer from the disease. Aniridia might also appear sporadically, which means without any family history, and this occurs in one third of all patients.
In some cases, serious and incapacitating diseases, such as Wagr Syndrome (genetic disorder linked to chromosome 11) or Wilms’ Tumour (a rare kidney cancer), might trigger aniridia.
There is currently no possible cure for aniridia, so therapies are aimed at treating the complications it entails. It often requires a multi-disciplinary approach by a team of ophthalmologists who specialise in each of the ocular areas and who are experts, for example, in glaucoma surgery, cataract surgery or corneal transplantation.
In children with aniridia, it is important to apply stimulation and rehabilitation techniques to encourage the development of the greatest visual potential possible and avoid psychomotricity problems. The Poor Vision Areas of the Miranza clinics offer different assistance through special glasses, magnifying glasses, suitable screens, voice assistants, etc.
Finally, we can also improve the appearance of the eye, which is missing its coloured part, through the use of cosmetic or prosthetic contact lenses, implantable artificial irises or reconstructive ocular microsurgery.