Peters anomaly (OMIM 604229) is a rare disorder characterized by corneal opacity with posterior corneal defects, and various degrees of iridocorneal and/or lenticulocorneal attachments (▶ Fig. 7.1). It is often caused by mutations of anterior segment development genes, such as the PAX6 gene. It is a malformation sequence primarily the result of failure of the lens to be created properly from surface ectoderm in response to the induction of the underlying optic vesicle. Neural crest migration to form the cornea and anterior segment structures are secondarily disrupted. Visual prognosis is usually based on location and size of the resulting scar. Most affected individuals are bilaterally involved and those with bilateral involvement are more likely to have associated systemic malformations. Treatment choices include corneal transplantation and/or lens extraction if cataract is present. For less severe cases, an optical iridectomy may be performed or pharmacologic dilation used. Patients have a lifetime risk of glaucoma with or without corneal surgery.
Fig. 7.1 Peters anomaly. (a) Note central corneal opacity with shallow anterior chamber and cataract. There are iridocorneal adhesions from the pupil to the corneal scar. (b) Posterior corneal defect. Note also the shallow anterior chamber and iridocorneal adhesions.
Rarely, patients with Peters anomaly may have associated systemic abnormalities including short stature, cleft lip/palate, characteristic facial features, and developmental delay, which are designated Peters plus syndrome (MIM 261540). In these individuals, developmental delay is seen in approximately 80% of children. Peters may also present with a wide variety of other malformations in the absence of skeletal dysplasia with or without a defined syndromic diagnosis other than true Peters plus.
7.2 Molecular Genetics
Most cases are sporadic. Autosomal recessive and autosomal dominant inheritance has been reported. Mutations of anterior segment development genes can lead to Peters anomaly. Peters anomaly had been associated with mutations in the PAX6 gene (autosomal dominant, 11p13, OMIM 607108). This gene is most commonly associated with aniridia, but Peters anomaly can occur without aniridia. The PITX2 (autosomal dominant, 4q25, OMIM 601542) and FOXC1 (copy number variations, autosomal dominant, 6p25, OMIM 601909) genes are reported more commonly with Axenfeld–Rieger spectrum. Mutations in the CYP1B1 gene (autosomal recessive, 2p22.2, OMIM 601771) are more commonly associated with congenital glaucoma. The FOXE3 gene (1p33, OMIM 601094) is also associated with primary aphakia. Other relevant genes include TFAP2A and FLNA when syndromic features such as facial dysmorphism, hearing loss, velopharyngeal insufficiency, short stature, kidney hypoplasia, and heart and skeletal abnormalities are present, and HCCS, NDP, and SLC4A11 in patients with isolated Peters anomaly.
Beta-1,3-galactosyltransferase-like glycosyltransferase (B3GALTL) is the only gene in which mutations are known to produce Peters plus syndrome. Most affected individuals are homozygous for a splice-site mutation in intron 8 (c.660+1G>A). Peters plus syndrome is inherited in an autosomal recessive manner. Deletions and duplications of the gene’s locus, 13q12.3, may also result in Peters plus syndrome.
7.3 Differential Diagnosis
7.3.1 Birth Trauma
Birth trauma of the cornea due to forceps may cause a break in Descemet’s membrane with overlying stromal edema. Usually one can visualize vertically oriented, straight-edged, parallel lines on the endothelium. Forceps-related trauma usually presents with periorbital soft tissue injury, normal intraocular pressure, and normal corneal size.
7.3.2 Congenital Hereditary Endothelial/Stromal Dystrophy
Congenital hereditary endothelial/stromal dystrophy usually presents in infancy or early childhood with a completely and totally cloudy cornea, which is thick and has a “ground glass” appearance.
7.3.3 Corneal Dermoids
Corneal dermoids are rarely seen. Some syndromes, such as Lowe or Rubinstein–Taybi, can present with bilateral lesions.
7.3.4 Metabolic Disorders
Metabolic disorders in which substances are deposited in the cornea (e.g., mucopolysaccharidoses) can present with cloudy corneas in infancy but rarely at birth. The anterior segment is otherwise normal.
7.3.5 Intrauterine Keratitis
Intrauterine keratitis such as herpetic or rubella may result in cloudy cornea in infants. Posterior synechia from uveitis may mimic the iris abnormalities of Peters anomaly.