760 PEKCY FRIDEKBERG 



changes which point definitely and directly to the underlying disturbance, 

 that of calcium metabolism again in the case of congenital fragilitas ossium 

 with blue sclerae, or of similar states with corneal abiotrophies such as 

 buphthalmos or keratoconus. 



Cataract. The Lens. This ectodermal structure responds like others 

 of its kin (skin, nails, teeth, hair) to various disturbances of nutrition, 

 especially to deficiency diseases and dyscrinisms. The influence of nutri- 

 tive disturbances in the causation of developmental defects is suggested by 

 the experimental production of cataract in the young by sensitizing preg- 

 nant rabbits with lens tissue. 



In chronic tetany there is an early development of cataract, always 

 bilateral, of a peculiar type. It is perinuclear and lamellar (Barker). 

 This would indicate a nutritive disturbance with intermissions, pointing 

 to continued spastic contraction of the nutrient vessels in iris, ciliary 

 body and choroid. The nucleus, being furthest from the capsule from 

 which osmotic nutrition takes place, suffers most. There is an analogy 

 here with the selective disturbances in the extremities in such grave vas- 

 cular, nutritional diseases as thrombophlebitis obliterans, and perhaps,- 

 pellagra, in which cataract has also been observed. 



The teeth defects, transverse furrows, holes, or parallel horizontal 

 grooves (Barker) especially in canines and incisors, in tetany, are, sim- 

 ilarly nutritional disturbances at the peripheral point of least resistance, 

 or, rather, least nutrition. 



It seems logical to attribute the lens changes to a spasmophilia in- 

 volving the arteries of the uveal tract. The underlying biochemical proc- 

 ess is explained by Verhoeff as a persistence of lipoid droplets normally 

 present in the fetal lens due to a faulty fat metabolism dependent 001 or 

 associated with disturbances of calcium metabolism. 



Changes in the epithelium of the ciliary body, and swelling with hy- 

 dropic degeneration of the pigment layer of the posterior surface of the iris 

 in cataract of tetany and that of pregnancy further support this view. 

 The deficiency cataracts of childhood are generally lamellar, partial, and 

 stationary, and may interfere only slightly with vision. 



In adults the lens changes are more usually nuclear, and tend to pro- 

 gress rapidly, with a decided hardening of the nucleus and the final de- 

 velopment of a completely opaque lens. 



Senile Cataract. Like the skin, the lens shows, exquisitely, the onset 

 of old age, and like the blanching of the hair, it is, one may say, a physio- 

 logical change. However, just as we may have a pre-senility due to dys- 

 crinism which shows itself in skin changes (geroderma) so an early de- 

 velopment of arcus senilis, or of lenticular opacities, or diffuse cataract 

 may indicate a gradual loss of the hormones which preserve youth. 



The significance of arterial supply for the nutrition of the lens is sug- 

 gested by the development of so-called heterochromic cataract or unilateral 



