- Aniridiya reasons
- Aniridiya symptoms
- Treatment of an aniridiya
Aniridiya is an inborn genetic disease, in translation from Greek literally means "lack of an iris of the eye" (a color part of an eye).
Disease this very difficult and rather poorly studied.
A few years ago, when this phenomenon received the name "aniridiya", it was not known that this name will describe only one symptom of an aniridiya, without capturing all essence of a disease.
Today it is known that lack of an iris of the eye is only minor aspect of an aniridiya, and it does not reflect the most important aspects of a zaboleaniye capable to lead to a bigger loss of sight and other problems in bodies and systems of an organism.
Aniridiya happens because of defect in PAX6 gene located in an upper part of the eleventh chromosome. This chromosome has two departments known as "р" and part "q"; "р" a part is shorter, and "q" a part is longer. Genes are small segments of the genetic material known as DNA and regulating several important functions in a body. For the first time the aniridiya is documented as a genetic disease bolee150 years back. Since then she became an example of autosomal and dominant genetic disorders. The gene of an aniridiya was distributed on a short part of the 11th chromosome, and this gene received the name RAH6, it regulates development of an eye and central nervous system. At an aniridiya of change in a gene of RAH6 can lead both to insignificant loss of visual acuity, and to serious defects of a nervous system and a full osutstviye of eyes.
The gene of RAH6 is inherited is prepotent, and it means that one abnormal gene replica is enough to cause a disease. If the person has both abnormal copies, then it leads to a severe form of a disease. The child can die at the birth or it can have heavy anomalies, such as: lack of eyes, large ears, defects of a nose, underdevelopment of a brain, anomaly of cranial bones. All cases of an aniridiya – genetic, caused by mutations which prevent RAH6 gene to function normally. This mutation can be expressed or in total absence of a part of the 11th chromosome which contains RAH6 gene, or in an izmeniya of components of a gene that in turn breaks its normal functioning.
Each person has two copies of each gene. One copy is transferred from mother, another from the father. If one copy normal, and another abnormal, and the person healthy, then a gene shows a recessive mode of inheritance. It means that one abnormal gene replica is not enough to cause a disease. If the person has one normal copy, and another abnormal, and he is exposed to a disease, then the gene shows a dominant mode of inheritance. It means that one abnormal copy is enough to cause a disease.
Eye manifestations at patients with an aniridiya include a photophobia (light sensitivity), also often it is a nystagmus (the involuntary movements of eyes), decrease in sight, an amblyopia (decrease in sight without visible physical defects or a disease), squint, opacification of a cornea, glaucoma, anomalies of a crystalline lens, anomaly of a retina and anomaly of an optical nerve. Many patients have a characteristic mimicry with the made narrower palpebral fissure and wrinkles on a forehead, all this occurs in the investigation of a photophobia. Children often look frowningly or roll up eyes.
At an aniridiya a cornea usually a bessosudist (there are no blood vessels) because of transparent allocations in a front part of an eye. People with an aniridiya become vaskulyarizirovanny. The heap of bloody vessels grows on a cornea. This outgrowth is called a pannus.
The corner of an anterior chamber is a part of an eye between a cornea and an iris of the eye which drains liquid in an eye and supports the normal level of pressure. Aniridiya influences this part of an eye and interferes with a liquid effluence from an eye, thus the increasing pressure in an eye leads to glaucoma.
Lens – biconvex structure behind an iris of the eye which focuses the light beams arriving on a retina which turns these light signals into electric signals and leads them to a brain through optic nerves. At an aniridiya there can be an ectopia lentis from a normal position, it is called an incomplete dislocation or dislocation of a crystalline lens, and also usually transparent lens can become lightproof that is called a cataract.
The pole is area of a retina which is responsible for accurate sight. It can be underdeveloped; it is called a fovealny hypoplasia and influences sight. The optic nerve can be underdeveloped too, weakening sight even stronger.
Undoubtedly, all these anatomic anomalies and functional problems lead to deterioration in sight, to a nystagmus (the involuntary movements of eyes), squint, etc.
Treatment of an aniridiya:
Symptomatic treatment. Carrying the cosmetic contact lenses painted on the periphery is appointed than imitation of a pupil is created. Reconstructive plastic surgery (kollagenorekonstruktion) can be performed.