Congenital aniridia

Introduction Anirida is a developmental disorder in both eyes. It is characterized by congenital iris dysplasia or the absence of normal iris. It can also be associated with various eye diseases such as corneal opacity, small cornea, lens dislocation, cataract, glaucoma, Macular dysplasia, strabismus, nystagmus, etc., involving the entire eye. Due to the different degree of iris defect, the clinical manifestations are different, but there are signs of photophobia, frowning and blinking, poor visual acuity and possible progressive decline. Clinically, some of the affected eye irises can be seen by flashlight or when the slit lamp is inspected, and some can only see the residual iris root tissue under the corner mirror.

Cause

(1) Causes of the disease

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.

(two) pathogenesis

There are two main theories, ectodermal theory and mesodermal theory. In addition, environmental factors should also be taken as a teratogenic factor. The ectodermal theory believes that at 12 to 14 weeks of gestation, neuroectodermal developmental disorders, resulting in the lack of development of the cup edge, leading to iris development and other ectodermal defects, such as retinal, macular dysplasia, lack of pupil muscle. The mesodermal theory suggests that the mesoderm developmental disorder occurs in the second month of the embryo. The lens capsule-pupil vessels of the lens membrane of the lens are not atrophied and the residual growth hinders the growth of the edge of the cup. The mesoderm extends forward into the ectoderm and the edge of the cup. At the time, it appears as a narrow band around the anterior chamber, blocking the ectodermal growth, resulting in iris dysplasia. But this theory cannot explain other neuroectodermal dysplasia.

an examination

1. Genetic testing can detect which genetic type is present in patients without iris.

2. Family history survey

Understand any abnormalities in the eye and/or low vision, abnormal teeth, umbilical herniation, genitourinary abnormalities, including Wilms' tumor or mental retardation.

3. Comprehensive inspection

Includes dentition, umbilical, genitourinary system (including MRI) and central nervous system (including MRI).

4. Eye examination

And check their parents and other close relatives. The ocular examination must include fluorescein angiography of the anterior segment of the eye and the posterior segment of the eye to detect lesions with normal appearance of the iris and macula, but with abnormalities in the iris ciliary region and abnormalities in the foveal avascular region.

Differential diagnosis

It should be differentiated from congenital iris deficiency: congenital iris deficiency: the iris is completely missing, and the lens equatorial edge, suspensory ligament and ciliary process can be directly seen. There may be low vision caused by photophobia and various eye abnormalities, and more patients are blind due to progressive cornea, lens opacity or glaucoma. To reduce the photophobia, wear colored glasses or contact lenses.

Congenital iris-free iris roots often have different degrees of residual iris, and can also be associated with a variety of eye diseases. Due to the different degree of iris defect, the 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 of the affected eye irises can be seen by flashlight or when the slit lamp is inspected, and some can only see the residual iris root tissue under the corner mirror. In many patients, there are peripheral corneal vasospasm and corneal opacity, which gradually progress to the central part of the cornea with age. Occasionally small cornea, keratosis and adhesion of the cornea to the lens. Lens dysplasia is congenital localized lens opacity is more common, there may be lens ectopic or congenital defects, the occurrence of progressive cataract can significantly reduce vision. Iris-free can also be associated with choroidal defects, residual pupillary membrane, small optic nerve head, strabismus and ptosis, such as dysplasia with the center of the macula can cause nystagmus.

There is 50% to 75% of glaucoma patients without iris, and the occurrence of glaucoma is related to the state of the angle of the anterior chamber. In the absence of glaucoma, the angle of the iris shows that the iris's stump maintains the normal plane of the iris, the iris of the root does not adhere to the trabeculae, and the "pupil edge" has no valgus. When accompanied by glaucoma, the residual iris gradually covers the trabecular mesh forward, and once the functional trabeculae is blocked, the intraocular pressure gradually increases. The severity of glaucoma is associated with adhesions in the anterior chamber. When glaucoma has occurred in infants or very young children, the largest change in the angle of the anterior chamber is that the iris matrix is jagged in different angles of the corner of the anterior wall, or the residual iris matrix from the periphery is past the ciliary body and the sclera. Xiaoliang online. Over time, usually after a few years, these adhesions of the iris gradually become denser and wider, and the pigmentation increases, and migrates forward, making it difficult to see the previously seen ciliary body, sclera and trabecular mesh. As the corner of the room changes progressively, the intraocular pressure naturally increases.

Combined with systemic abnormalities and diseases, there are mainly iris Wilms tumor syndrome, and 25% to 33% of congenital sporadic patients with no iris occur before the age of 3 years. In addition to kidney Wilms tumors, there are mental retardation, abnormal genitourinary or craniofacial deformities, low ear position. This syndrome is more developed than the general iris-free and is associated with congenital anomalies in other systems, and is familial. Sporadic aniridia with congenital abnormalities and mental retardation of the genitourinary system is called the ARG triad and is thought to be related to the intermediate deletion of the short arm of chromosome 11. In addition, systemic abnormalities can be seen in glandular cell tumors, cerebellar ataxia, hemifacial body hypertrophy, cryptorchidism, small head and cleft lip.

Clinically, this congenital anomaly is easy to diagnose. On the basis of combined eye and system abnormalities, there are four types of no iris: 1 with nystagmus, corneal vasospasm, glaucoma, and vision loss; 2 with obvious iris defect, but better visual acuity; Wilms tumor (no iris-Wilms tumor syndrome) or other abnormalities of the genitourinary system; 4 with mental retardation.

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