Aniridia
The content of the article:
- Causes and risk factors
- Forms of the disease
- Symptoms
- Diagnostics
- Treatment
- Possible complications and consequences
- Forecast
- Prevention
Aniridia (irideremia) is an ophthalmic disease, manifested by hypoplasia (underdevelopment) of the iris of the eyes. The disease is rare (approximately 1 in 70,000 people). Both men and women suffer from it with the same frequency.
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Causes and risk factors
Aniridia may be one of the manifestations of WAGR syndrome and Gillespie syndrome. But usually the cause of the underdevelopment of the iris is a mutation in the PAX6 gene, located on the 11th chromosome.
In 65% of cases, aniridia is inherited. Depending on the type of mutation, the disease can be inherited both in an autosomal recessive and autosomal dominant manner. In 35% of cases, aniridia occurs due to a spontaneous gene mutation.
Another reason for the development of aniridia is trauma to the eyeball, in which the iris is detached from the root.
Forms of the disease
Depending on the origin, two forms of aniridia are distinguished:
- congenital;
- traumatic (acquired).
According to the features of the clinical course of aniridia, it happens:
- partial;
- complete;
- associated with WAGR syndrome or Gillespie syndrome.
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Symptoms
The full form of aniridia is characterized by the almost complete absence of the iris in the patient, a significant decrease in visual acuity and severe photophobia. In addition, the following are noted:
- amblyopia;
- nystagmus;
- increased intraocular pressure;
- opacity of the cornea;
- optic nerve abnormalities;
- retinal abnormalities;
- lens abnormalities.
With partial aniridia, the symptoms are the same as with the full form of the disease, but less pronounced.
The clinical picture of WAGR syndrome, in addition to aniridia, includes the following symptom complex:
- impaired mental function;
- diseases of the urinary system, leading to the formation of chronic renal failure;
- malignant nephroblastoma (Wilms tumor);
- chronic pancreatitis;
- hemihypertrophy (pathological increase in the muscles of one half of the body).
Besides aniridia, Gillespie's syndrome is characterized by:
- pulmonary artery stenosis;
- ptosis;
- hearing impairment;
- mental retardation;
- cerebellar ataxia.
Diagnostics
Diagnosis of aniridia includes the following activities:
- Visual examination of the anterior sections of the eyeball. With complete aniridia, the iris is absent, with partial aniridia, small areas of the iris are visible.
- Ophthalmoscopy. Allows to identify possible pathology of the optic nerve and the central part of the retina, which is often observed in patients with aniridia.
- Tonometry (measurement of intraocular pressure). With aniridia, in many cases, there is an increased intraocular pressure, which poses a potential risk of developing glaucoma.
- Gonioscopy (examination of the anterior chamber of the eye). Usually performed in patients with increased intraocular pressure.
- Clinical refraction study. For this, refractometry, direct ophthalmoscopy and skiascopy are performed.
- Ultrasonic biomicroscopy. Allows you to explore the fundus, as well as examine the residual areas of the iris.
Diagnosis of aniridia begins with an examination of the anterior sections of the eyeball
In congenital aniridia, genetic tests are shown to detect a defect in the PAX6 gene. Taking into account the fact that aniridia may be one of the symptoms of WAGR syndrome, patients are shown a FISH test to detect the presence of a malignant neoplasm (Wilms tumor).
Treatment
Treatment can be surgical or conservative. Surgical correction of the defect is based on the implantation of an artificial iris. The implant is made of a special hydrogel, the color of which corresponds to the natural color of the patient's eyes, and has a hole for the pupil in the middle. Surgical correction is indicated primarily for patients with acquired aniridia.
In congenital form of the disease, the installation of an iris implant can be performed only with minor changes in the cornea. If aniridia is combined with cataract, the patient is simultaneously implanted with iris and lens prostheses.
Implantation of an artificial iris is indicated for patients with acquired aniridia
Conservative treatment of aniridia consists in the use of cosmetic (colored) contact lenses that mask the existing iris defect.
With increased intraocular pressure, eye drops are prescribed, which include beta-blockers, prostaglandins or carbonic anhydrase inhibitors. To reduce the risk of pathological changes in the cornea, it is necessary to use special moisturizing drops or gels.
With aniridia, it is very important to protect the eyes from exposure to ultraviolet rays. When outdoors, patients must always wear sunglasses that block 100% of the sun's UV rays.
Possible complications and consequences
Congenital aniridia is often accompanied by the development of cataracts and glaucoma.
Forecast
If the recommendations of the attending physician are followed, the prognosis is generally favorable.
Prevention
Since congenital aniridia is a genetic disease, there are no measures to prevent it. If there are cases of this pathology in the family, a medical and genetic consultation is recommended when planning a pregnancy.
Prevention of acquired aniridia includes measures aimed at preventing injury to the eyeball.
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Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
