SHORTER ARTICLES AND DISCUSSION 



INHERITANCE OF CONGENITAL CATARACT 



Cataract is the opacity of the eye caused by a faulty forma- 

 tion of the lens. Certain forms of cataract are congenital and 

 hereditary. Other forms which appear later in life may either 

 be hereditary or due to pathological causes. 



In the normal eye the delicate fibers which go to make up the 

 lens are glued together along their sides and at their ends where 

 they unite in lines radiating from the poles of the lens to form 

 a completely transparent body. Anything which prevents the 

 perfect conjunction of these fibers causes a defect in the trans- 

 parency of the lens. This imperfection has been compared by 

 Harman (2) to the white spots in the finger nail, caused by slight 

 injuries to the nail bed, and he has shown it to be correlated with 

 faulty formation of the dental enamel. 



There are various causes for the inhibition of proper lens de- 

 velopment, and these give rise to different forms of cataract. 

 Only those forms have been considered here which are congenital. 



The most common form of congenital cataract is the lamellar, 

 perinuclear or zonular cataract. This manifests itself as a dark 

 circular disk with the density increasing from the center to the 

 perimeter, forming characteristic zones. These zones are flecked 

 by small wedge-shaped dashes arranged regularly in a spoke- 

 fashion about the disk. The disk is located between the nucleus 

 of the lens and the cortex ; and is caused by a thickening of the 

 layers at that place. 



Discoid cataract is a slight form of the lamellar, less than 4 

 mm. in diameter, and located at the posterior pole of the lens. 

 The opacity is uniform throughout, but is not easily visible. 

 (It is sometimes confused with anterior polar cataract, of which 

 the origin is not definitely known, but which is not congenital.) 



Coralliform or axial cataract, cataracta fusiformis, is an 

 opaque line running through the lens from anterior to posterior 

 pole with a spindle-shaped swelling towards the center of the 

 lens. 



Anterior and posterior cortical cataract, cataracta corticallis, 

 where the opacity takes a more or less geometrical outline, 

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