Other corneal dystrophies
 

Crystalline dystrophy of Schynyder Cloudy dystrophy of Francõis Posterior polymorphous endothelial  dystrophy Map-finger-dot epithelial dystrophy

In the examination, the most common dystrophies you are likely to see are Reis-Buckler's, lattice, granular,  macular and Fuch's endothelial dystrophies. As there are many different types of dystrophies, you may well be  given less common types. Begin your presentation by describing which layer (epithelium, anterior or posterior  stroma or endothelium) is involved, the pattern of the opacities (crystalline, vesicles, lines or circular etc), and  if the opacities involves the centre or the periphery of the cornea. Schynyder central crystalline dystrophy There are multiple small white crystals in the centre of the cornea just below the Bowman's membranes.  The surface of the cornea is uninvolved and there may be corneal arcus Central cloudy dystrophy of Francõis There are multiple greyish nebulous opacities separated by crack like clear zones (the changes may resemble  crocodile shagreen). The opacities are denser in the centre and the posterior aspect of the cornea. Posterior polymorphous dystrophy There are multiple vesicles in the endothelium. There are also multiple greyish opacities which may be curvilinear  or has scalloped edges. In some patients there may be stromal oedema or abnormal iris shape such as corectopia  or iridocorneal adhesion (the changes may resemble ICE syndrome but the condition is bilateral) Map-dot-fingerprint dystrophy (Cogan microcystic dystrophy) Although a common epithelial dystrophy, it seldom appears in the examination.  There are multiple opacities in the epithelium and has shapes resembling map lines, dots/microcysts or fingerprint  lines. .

Questions:

1. How are the above dystrophies inherited?

Answer
Map-dot-fingerprint dystrophy has a dominant inheritance with incomplete penetrance
Schynyder central crystalline dystrophy, central cloudy dystrophy of Francõis and posterior polymorphous endothelial dystrophy are all autosomal dominant condition.

2. How many different type of  endothelial dystrophies do you know of and how do they present?

Answer
There are three common endothelial dystrophies and they can all present with endothelial failure with corneal oedema. However, the onset of symptoms and the severity differ between the three.
Fuchs' endothelial dystrophy: autosomal dominant; usually present in the fifth to sixth decade with corneal oedema
Posterior polymorphous dystrophy: autosomal dominant; most patients are asymptomatic but in some there may be corneal oedema. The trabecular meshwork and the iris may be involved by the abnormal endothelium giving rise to glaucoma and abnormal iris shapes
Congenital hereditary endothelial dystrophy: may be autosomal dominant or recessive. The recessive form is associated with severe corneal oedema at birth.

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