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Posterior polymorphous corneal dystrophy

AI overview

Posterior polymorphous corneal dystrophy is a type of corneal dystrophy, characterised by changes in Descemet's membrane and endothelial layer.

Key points
  • PPCD type 2 is linked to mutations in COL8A2, type 3 to ZEB1, and type 1 is unknown.
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    PPCD type 2 is linked to the mutations in COL8A2 , and PPCD type 3 mutations in ZEB1 gene, but the underlying genetic disturbance in PPCD type 1 is unknown.
  • The disease was first described in 1916 by Koeppe as keratitis bullosa interna.
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    The disease was first described in 1916 by Koeppe as keratitis bullosa interna .
  • The endothelium is often multilayered and has characteristics of an epithelium, including desmosomes, tonofilaments, and microvilli.
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    In posterior polymorphous corneal dystrophy, the endothelium is often multilayered and has several other characteristics of an epithelium, including the presence of desmosomes, tonofilaments, and microvilli.
Symptoms
  • Symptoms mainly consist of decreased vision due to corneal edema.
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    Symptoms mainly consist of decreased vision due to corneal edema.
  • Symptoms may be present from birth or patients may be asymptomatic.
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    In some cases they are present from birth, other patients are asymptomatic.
Diagnosis
  • Histopathological analysis shows endothelium cells have epithelial characteristics and are multilayered.
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    Histopathological analysis shows that the cells of endothelium have some characteristics of epithelial cells and have become multilayered.
  • Vacuoles are demonstrated in the posterior parts of the cornea.
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    Vacuoles are demonstrated in the posterior parts of the cornea .
Red flags
  • Abnormal cells can extend onto the trabecular meshwork to cause glaucoma in up to 40% of cases.
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    extend onto the trabecular meshwork to cause glaucoma in up to 40% of cases.
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Posterior polymorphous corneal dystrophy
Other namesOphthalmology
Appearance of the abnormal corneal endothelial cells that have become transformed into stratified squamous epithelium. Periodic acid Schiff (PAS) stain

Posterior polymorphous corneal dystrophy (PPCD; sometimes also Schlichting dystrophy) is a type of corneal dystrophy, characterised by changes in Descemet's membrane and endothelial layer. Symptoms mainly consist of decreased vision due to corneal edema. In some cases they are present from birth, other patients are asymptomatic. Histopathological analysis shows that the cells of endothelium have some characteristics of epithelial cells and have become multilayered. The disease was first described in 1916 by Koeppe as keratitis bullosa interna.[1]

PPCD type 2 is linked to the mutations in COL8A2, and PPCD type 3 mutations in ZEB1 gene, but the underlying genetic disturbance in PPCD type 1 is unknown.[citation needed]

Vacuoles are demonstrated in the posterior parts of the cornea. The vesicles are located on the endothelial surface. The corneal endothelium is normally a single layer of cells that lose their mitotic potential after development is complete. In posterior polymorphous corneal dystrophy, the endothelium is often multilayered and has several other characteristics of an epithelium, including the presence of desmosomes, tonofilaments, and microvilli. These abnormal cells retain their ability to divide and extend onto the trabecular meshwork to cause glaucoma in up to 40% of cases.[2]

  1. ↑ Albrecht von Graefes (1916). "Klinische Beobachtungen mit der Nernstspaltlampe und dem Hornhautmikroskop". Arch. Klin. Exp. Ophthal. 91 (3): 363–379. doi:10.1007/BF01974655.
  2. ↑ "Posterior polymorphous corneal dystrophy". Online Mendelian Inheritance in Man(OMIM).