Posterior corneal depression
Posterior corneal depression (central posterior keratoconus; von Hippel internal ulcer) is a discrete posterior corneal indentation with a normal anterior curvature; it can be considered a variant of Peters anomaly (see the following section). Pigment deposits sometimes are seen on the border of the defect. An abnormal red reflex is noted during examination with a retinoscope or direct ophthalmoscope. If refractive correction is not successful, Descemet stripping endothelial keratoplasty (DSEK) can be considered.
Peters anomaly (kerato-irido-lenticular dysgenesis) is characterized by a posterior corneal defect with an overlying stromal opacity, often accompanied by adherent iris strands (Peters anomaly type 1; Fig 21-7A). A more severe phenotype includes adherence of the lens to the cornea at the site of the central defect (Peters anomaly type 2; Fig 21-7B). The corneal opacity ranges from a dense to mild central leukoma (Fig 21-7C). In severe cases, the central leukoma may be vascularized and protrude above the level of the cornea. In rare cases, a membrane may form posterior to the posterior corneal defect, causing the appearance of a central cyst in an opacified cornea (Fig 21-7D). The stromal opacity may decrease with time in some cases. Lysis of adherent iris strands has been reported to improve corneal clarity in some cases.
Peters anomaly can arise from a variety of gene mutations (eg, heterozygous PAX6 mutation, biallelic CYP1B1 mutations) or from in utero insult (eg, congenital rubella). Unilateral cases are usually isolated. Bilateral cases warrant a complete genetic evaluation. One Peters anomaly syndrome is Peters-plus syndrome, which is caused by biallelic B3GLCT mutations. Peters-plus syndrome is associated with short stature, a distinct craniofacial appearance, shortened fingers and toes, and intellectual disability. In this syndrome, the stromal opacity may diminish with time.
Bhandari R, Ferri S, Whittaker B, Liu M, Lazzaro DR. Peters anomaly: review of the literature. Cornea. 2011;30(8):939–944.
Khan AO, Al-Katan H, Al-Gehedan S, Al-Rashed W. Bilateral congenital stromal cyst of the cornea. J AAPOS. 2007;11(4):400–401.
Nischal KK. Genetics of congenital corneal opacification—impact on diagnosis and treatment. Cornea. 2015;34(Suppl 10):S24–S34.
A, Corneal opacity secondary to iridocorneal adhesion (Peters anomaly type 1). B, Corneal opacity secondary to keratolenticular adhesion (Peters anomaly type 2). C, A Peters phenotype of central lens opacity with keratolenticular adhesion. D, Bilateral posterior corneal defect with a thin posterior membrane, causing the appearance of a central cyst in an opacified cornea.
(Parts A and B courtesy of Ken K. Nischal, MD; parts C and D courtesy of Arif O. Khan, MD.)
Sclerocornea (total corneal opacification) is a descriptive term for a congenitally opaque cornea resembling sclera (Fig 21-8). As it is a vague term that does not suggest causation, its use should be avoided.
Congenital or infantile glaucoma
Glaucoma in young children can cause the cornea to become edematous, cloudy, and enlarged. Breaks in Descemet membrane from glaucomatous enlargement are termed Haab striae (Figs 21-9, 21-10). See Chapter 22 for further discussion.
Figure 21-8 Bilateral sclerocornea.
(Courtesy of Arif O. Khan, MD.)
Figure 21-9 Primary congenital glaucoma.
(Reproduced with permission from Khan AO. Genetics of primary glaucoma. Curr Opin Ophthalmol. 2011;22(5):347–355.)
Figure 21-10 Haab striae in an eye that underwent peripheral iridectomy during prior glaucoma surgery.
(Courtesy of Arif O. Khan, MD.)
Traumatic breaks in Descemet membrane
Traumatic breaks in Descemet membrane can be caused by forceps trauma during delivery. Other signs of trauma are frequently apparent on the child’s head. Traumatic breaks are usually vertical and linear, unlike the curvilinear and often horizontal Haab striae of congenital glaucoma. Acute rupture leads to stromal and sometimes epithelial edema. Acute stromal and epithelial edema regresses, but the edges of the broken Descemet membrane persist and can be seen as ridges protruding slightly from the posterior corneal surface. Amblyopia may result from prolonged corneal opacity or, more commonly, from induced anisometropic astigmatism. In patients with brittle cornea syndrome, a disorder of corneal fragility caused by biallelic mutations in ZNF469 or PRDM5, minor trauma can cause traumatic breaks in Descemet membrane (Fig 21-11).
Congenital corneal ulcers are rare and may be caused by herpes simplex keratitis or other infection (see Chapter 28).
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.