Aniridia: causes, symptoms, diagnosis, treatment

Congenital aniridia is the absence of the iris. Upon careful examination, small fragments of the root and iris are sometimes found. This pathology can be combined with other developmental defects - microphthalmos, subluxation of the lens, nystagmus. Congenital aniridia is accompanied by amblyopia, hyperopia, and sometimes secondary glaucoma. Aniridia can also be acquired: as a result of a strong blow, the iris can completely break off at the root.

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Heredity

1. Autosomal dominant. The most common form of inheritance. The disease is bilateral and has varying expressivity.
2. Autosomal recessive. Occurs less frequently; is part of the symptom complex of Gillespie syndrome.
3. Sporadic origin occurs in approximately one third of all cases of aniridia. In some situations, a 13p deletion is found. Aniridia may be associated with Wilms' tumor, mental retardation, genitourinary pathology, and malformations. Patients with this form of aniridia undergo a thorough karyotype examination or fluorescein in situ hybridization. Genetic testing at the molecular level is indicated to detect mild degrees of deletion. In all cases of sporadic aniridia, abdominal palpation and ultrasound examination are performed every three months during the first five years of life to exclude Wilms' tumor. There are isolated reports of familial development of this tumor.

How does aniridia manifest itself?

Aniridia is always accompanied by a decrease in visual acuity. Patients are forced to shield their eyes from excessive light with their eyelids.

Complete aniridia

• The remnants of the iris root are identified.
• Associated anterior polar cataract.
• Peripheral vascular corneal dystrophy.
• Dislocation of the lens.
• Glaucoma.
• Macular hypoplasia.
• Nystagmus.
• Optic nerve hypoplasia.
• Visual acuity ranges from 6/36 to 3/60 (0.05 to 0.16).

Partial aniridia

Partial absence of the iris. Symptoms are the same as complete aniridia, but expressed in a milder form. Manifestations may be subtle, such as mild hypoplasia of the iris stroma.

Aniridia in combination with other pathology

• Gillespie syndrome, aniridia associated with cerebellar ataxia and mental retardation.
• Aniridia in the absence of the patella.
• Other combinations.

Treatment of aniridia

In recent years, this defect has been successfully eliminated using an artificial iris made of colored hydrogel, in the center of which there is a hole 3 mm in diameter, simulating the pupil. In case of unilateral aniridia, the color of the artificial iris is selected according to the color of the healthy eye.

Insertion of an iris prosthesis is a difficult abdominal operation. To suture the prosthesis, a transscleral surgical approach is required in diametrically located areas of the limbus. If aniridia is combined with cataract, it is removed and a prosthesis is inserted that replaces both the iris and the lens.

Tactics of management

• Refraction: often marked ametropia is present.
• Prescribing glasses and, in some cases, contact lenses.
• Use of devices for visually impaired patients.
• Organization of the education system.
• Detection of glaucoma in the early stages of its development.
• Young children may require examination under general anesthesia.
• Most forms of cataracts associated with aniridia are of little functional significance, but over time,
  visual acuity may decrease due to progression of the cataract or the development of amblyopia.