History
Because the ocular abnormalities of Peters anomaly are noted at birth, the obstetrician or the pediatrician is often the first to observe them. The child may be completely asymptomatic or may have other ocular or systemic anomalies.
Physical
Central, paracentral, or complete corneal opacity (leukoma) is always present in patients with Peters anomaly. The size and density of the leukoma vary. Usually, no vascularization of this opacity occurs, which helps in distinguishing it from other causes of congenital corneal opacity. [15, 16, 17] The corneal periphery is usually more lucent.
Eighty percent of type 1 Peters anomaly cases are bilateral. Central or paracentral corneal opacity is present. The surrounding peripheral cornea may be clear or edematous because of glaucoma. The cornea is avascular. Iris strands often extend across the anterior chamber to the posterior surface of the cornea. These may be filamentous or thick strands or sheets. The opacity is caused by a defect in the underlying corneal endothelium and the Descemet membrane. The lens may be clear or cataractous. [6]
Type 2 Peters anomaly is characterized by adhesions between the lens and the cornea. Cases are usually bilateral. The corneal opacity is denser and may be central or eccentric. The lens is usually cataractous and typically is juxtaposed to the cornea. The posterior stroma, the Descemet membrane, and the endothelium are defective. Iris strands may or may not be present. Other ocular and systemic abnormalities are more common in type 2 than in type 1.
Bilateral Peters anomaly has a stronger association with systemic malformations than does unilateral Peters anomaly. [2]
Other ocular abnormalities
Peters anomaly may be associated with microcornea, cornea plana, sclerocornea aniridia, and glaucoma due to dysgenesis of the angle [18] . Glaucoma occurs in up to 90% of cases. Colobomas of the iris and the choroid, as well as PHPV, have been reported. Optic nerve hypoplasia or atrophy also can occur. One case of Goldenhar syndrome with Peters anomaly has been reported. [19]
Systemic abnormalities
Peters anomaly is seen in trisomy 13-15, ring chromosome 21, [20] Norrie disease, partial deletion of chromosome arm 11q, mosaic trisomy 9, and 49XXXXY syndrome.
Systemic associations in Peters anomaly include developmental delay, congenital heart disease, structural defects of the neurologic system, spinal defects, genitourinary abnormalities, external ear abnormalities, hearing loss, cleft lip and palate, and short stature.
Krause-Kivlin syndrome
Krause-Kivlin syndrome is an autosomal-recessive condition characterized by Peters anomaly, short stature, facial dysmorphism, developmental delay, and delayed skeletal maturation. [21]
Other associated abnormalities
Peters anomaly may also be associated with brachycephaly, brain malformation, cardiac anomalies, genitourinary anomalies, syndactyly, cleft lip and palate, and hearing abnormalities. [22, 23, 24, 25]
Causes
The cause of Peters anomaly is unknown; it may be caused by genetic factors, environmental factors, or both. The critical event must occur in the first trimester of pregnancy during the formation of the anterior chamber.
Most cases of Peters anomaly are sporadic; however, the literature has described autosomal-recessive pedigrees and rare autosomal-dominant pedigrees.
Mutations in FOXC1, PAX6, or PITX2 can cause Peters anomaly. The FOXC1, PAX6, and PITX2 genes are all homeobox genes that are involved in the development of the anterior segment of the eyes. [26]
Mutations in the CYP1B1 gene can also cause Peters anomaly. The CYP1B1 gene provides instructions for making an enzyme active in the eye. The role of the enzyme is unclear; however, it is likely involved in the development of the anterior segment. [27]
The RIEG1 gene is associated with Reiger syndrome. This gene is located on band 4q25. A case of Peters anomaly has been reported with this gene mutation. [9]
Another case of Peters anomaly was associated with abnormal centromere-chromatid apposition. [26]
Complications
Complications include amblyopia and decreased vision or blindness from glaucoma.
