congenital aniridia
Introduction
Introduction to congenital aniridia Congenital aniridia is a developmental disorder of both eyes, which can be associated with a variety of eye diseases such as corneal opacity, small cornea, lens dislocation, cataract, glaucoma macular dysplasia, squint nystagmus, etc., involving the entire eye. Some comorbidities are already present at birth, while others can be extended to childhood or early adulthood. Some patients may be accompanied by systemic abnormalities. But the term "iris-free" is actually a misnomer because the iris root remains and there is no complete iris-free. basic knowledge Sickness ratio: 0.0001% Susceptible people: young children Mode of infection: non-infectious Complications: mental retardation cataract
Cause
Congenital auria etiology
Environmental factors (30%):
Environmental factors should also be considered as teratogenic factors. The ectodermal theory believes that during the 12-14 weeks of gestation, the development of neuroectodermal barriers, the development of the cup edge is not developed, resulting in iris development and other ectodermal defects, such as the retina, the macula. Dysplasia, lack of pupil muscles, etc.
Developmental disorders (30%):
At the second month of embryonic mesoderm developmental disorder, the lens capsule-pupil vessels of the lens membrane of the lens are not atrophied and the residual obstructs the growth of the edge of the cup. The mesoderm extends forward into the ectoderm and the edge of the cup, which is the anterior chamber. A narrow band around the block that blocks the ectodermal growth, resulting in iris dysplasia, but this theory cannot explain other neuroectodermal dysplasia.
From the clinical manifestations, more evidence supports the developmental disorders of the neuroectoderm and mesoderm during embryonic development, resulting in various structural abnormalities in the eye of patients.
Prevention
Congenital aniridia prevention
1. Improve prenatal diagnosis technology, prevent the birth of genetic children, and improve the eugenic rate.
2, age-appropriate marriage, do not marry early, early pregnancy, do not be too late marriage, late pregnancy, to avoid the baby's congenital deficiency, planned eugenics. 3, pregnant women should pay attention to temperament, maintain a happy mood, peace of mind, avoid cold and heat, prevent disease, use drugs with caution, ban alcohol and tobacco, to avoid the effects of poisoning, trauma and physical factors.Complication
Congenital aniridia complications Complications, mental retardation, cataract
Some patients may also be accompanied by systemic abnormalities, including mental retardation, genitourinary dysplasia and Wilms tumor, as well as macular dysplasia, cataract and refractive error.
Symptom
Congenital Iris-free Symptoms Common symptoms Dreaded ptosis, nystagmus, cerebral palsy, local scleral swelling, lens opacity, small head corneal opacity, congenital, iris-free facial deformity, congenital iris deficiency
Congenital iris-free iris roots often have different degrees of residual iris, and can also be associated with a variety of eye diseases. Because of the different degree of iris defect, clinical manifestations are different, but there are signs of photophobia, frowning and blinking. Poor eyesight and possible progressive decline, associated with lack of iris, dysplasia of the macula, corneal opacity, cataract, glaucoma and refractive error, clinically some patients with flashlights or residual light can be seen when the slit lamp is inspected. Iris, and some can only see the residual iris root tissue under the corner mirror. Many patients have peripheral corneal vasospasm and corneal opacity, and gradually progress to the central part of the cornea with age, occasionally small cornea, Corneal sclerosis and corneal and lens adhesion, lens dysplasia is congenital localized lens opacity is more common, there may be lens ectopic or congenital defects, the occurrence of progressive cataract can make vision significantly reduced, no iris May also be associated with choroidal defects, residual pupillary membrane, small optic nerve head, strabismus and ptosis, such as with the center of the macula Dysplasia can lead to nystagmus.
There is 50% to 75% of glaucoma in patients with no iris. The occurrence of glaucoma is related to the state of the angle of the anterior chamber. There is no glaucoma. The angle of the iris can be seen in the normal plane of the iris, and the iris of the root is not The trabecular adhesions, "pupil edge" without valgus, when accompanied by glaucoma, the residual iris gradually covers the trabecular mesh forward, once the functional trabeculae is blocked, the intraocular pressure will gradually increase, the severity of glaucoma It is associated with the adhesion of the anterior chamber. When glaucoma has occurred in infants or very young children, the biggest change in the angle of the anterior chamber is that the iris matrix is jagged in different angles on the corner wall, or the iris matrix remaining from the periphery passes over the eyelashes. The striate and scleral processes stick to the trabecular meshwork. Over time, usually after several years, these adherent irises become denser and wider, and pigmentation increases, and migrates forward, making the ciliary body previously visible. The band, the scleral process and the trabecular meshwork are difficult to see. As the angle of the anterior chamber changes, the intraocular pressure naturally increases.
Combined with systemic abnormalities and diseases, there are mainly iris Wilms tumor syndrome, 25% to 33% of congenital sporadic patients with no iris occur before the age of 3, in addition to kidney Wilms tumor, and have mental retardation, genitourinary abnormalities or craniofacial Malformation, low ear position, etc., the syndrome is more developed than the general iris-free and is associated with congenital anomalies of other systems, and familial is rare, sporadic aniridia with congenital abnormalities and mental retardation of the genitourinary system Called the ARG triad, it is thought to be related to the intermediate deletion of the short arm of chromosome 11. In addition, systemic abnormalities can be seen in glandoma, cerebellar ataxia, hemifacial hypertrophy, cryptorchidism, small head and cleft lip.
Examine
Congenital aniridia
First of all, from the perspective of genetics, and can carry out the necessary genetic examination to understand what kind of genetic type, analysis of chromosome bands and other genetic analysis on the PAX-6 gene in each case of Iris patients, especially For everyone who can be used as a research.
Assume that it is a sporadic patient with no iris disease. It is necessary to first define whether there is no iris or other manifestations of anterior dysplasia. Further work should be done in the following aspects: 1 Comprehensive family history survey, especially to know about Any abnormalities in the eye and/or low vision, abnormal teeth, umbilical herniation, urogenital abnormalities including Wilms' tumor or mental retardation; 2 comprehensive examination of the patient, including dentition, umbilical, genitourinary system (including MRI) And the central nervous system (including MRI); 3 through the eye examination, and check their parents and other close relatives, eye examination must include fluorescein angiography of the anterior segment of the eye and the posterior segment of the eye to detect the appearance of the iris and macula However, there are abnormalities in the iris ciliary region and abnormalities in the foveal avascular region.
Diagnosis
Congenital aniridia diagnosis
Clinically, it is easy to make a diagnosis of this congenital anomaly. On the basis of ocular and systemic abnormalities, there are four types of no iris: 1 with nystagmus, corneal vasospasm, glaucoma, and vision loss; 2 obvious Iris defect, but better visual acuity; 3 with Wilms tumor (no iris-Wilms tumor syndrome) or other abnormalities of the genitourinary system; 4 with mental retardation.
