Aniridia is a rare congenital genetic disease, characterized by the absence of the iris. It's accompanied by photophobia, nystagmus, a strong decrease in visual acuity, with possible corneal degeneration, cataracts, glaucoma and other eye problems. In addition, aniridia may also be accompanied by pathologies of other organs and systems (nervous system, urinary system, endocrine system, digestion and other).
Word "Aniridia" in Greek literally means "the absence of the iris". Several years ago when the phenomenon was called "aniridia" nobody knew that this name would describe only one symptom of aniridi, without reflecting the whole essence of a disease.Today we understand, that the absence of the iris is only a minor aspect of aniridia, which does not reflect the all essence of this disease.
Aniridia is included among the orphan (rare) diseases, and it is insufficiently studied. American, Canadian, Israel, German scientists and doctros work actively on this subject, and we look forward for good results.
Why aniridia is a rare disease?
First, the birth rate of children with aniridia 1 to 50000 (100000) depending on the region. Sexual or racial traits have been identified.
Second, аniridia is rare, because one person can combined a several pathologies of vision (glaucoma, cataracts, macular degeneration, low vision, etc.) and pathology of other organs and systems of the body (WAGR syndrome, Gillespie syndrome , mental retardation, diabetes, obesity, autism, sensory disturbances, etc.). Determine the vulnerability of your child with aniridia to any of these disorders can be by using special genetic tests. (See " Aniridia is a complex disease" and "Genetic background of aniridia").
Aniridia is a congenital disease that means it's presence from the birth. Aniridia affects different structures of the eye and body systems. This happens when Pax6 gene (located on chromosome 11), which is responsible for development of the eye, nervous system, pancreas and intestine, does not work correctly. The result of this -developmental disorders of the iris, cornea, the angle of the anterior chambler of the eye, lens, retina (the sensory part of the eye) and the optic nerve (the nerve that carries visual impulses in the brain). Development disorders of these organs and systems of the body depend on the patient.
Eye problems of patients with aniridia often include a photophobia (sensitivity to light), nystagmus (involuntary eye movement), low vision, amblyopia ("lazy eye"), strabismus, corneal opacity, glaucoma, cataract , development disorders of lens, retina and hypoplasia of the optic nerve .
The cornea is normally an avascular aniridia (no blood vessels) , transparent tissue on the frontal part of the eye. In people with aniridia, it becomes vascularised. A bunch of blood vessels grows over the cornea. This outgrowth is called a pannus.
The angle of the anterior chamber - it's part of the eye between the cornea and the iris, which drains the fluid within the eye out of the eye and maintains normal levels of pressure within the eye. Aniridia affects this part of the eye and hampers the fluid flow out of the eye, thereby increasing the pressure within the eye causes glaucoma.
The lens is biconvex structure behind the iris that focuses light rays entering onto the retina, which converts these light signals into electrical signals and carries to the brain through the optic nerve. In aniridia there may be displacement of the lens from its normal position, which is called a subluxation or dislocation of the lens, or the normal clear lens of the eye can turn opaque, which is called cataract.
The fovea is the area of the retina that is responsible for clear vision. It may be underdeveloped, this is called foveal hypoplasia and affect vision. The optic nerve may be also underdeveloped, affecting vision.
Besides these anatomical abnormalities, there are functional problems in addition to decrease vision such as nystagmus, photophobia, squinting.
Aniridia is a congenital disease, which can be inherited from one parent (hereditary aniridia), or appear suddenly, when none of the parents have aniridia ( isolated (sporadic) aniridia).
Aniridia, unfortunately, nowadaysat is not treated. U.S. and Canadian scientists are actively exploring the possibility of gene therapy. Science can also help the family to have a healthy baby, and to reveal pathology of organs and systems of child with aniridia. To do this, we need to find a Spector of Pax6 gene mutations. That is why very important that all patients with aniridia do a genetic test and make registration on our website. We aim to create a census of these patients in Russia and start to study this problem with Russian scientists.