120 HEALTH AND DISEASE 



affects the capsule of the lens, cajisular cataract, and cataracts which exist 

 in the substance of the lens, lenticular cataracts (fig. 257). Capsular 

 cataracts usually appear on the front of the capsule, and in the form of 

 small circles or extremely minute specks, the smallest of which are only 

 rendered visible by the use of the ophthalmoscope. With this instrument 

 the examiner has no difficulty in distinguishing capsular cataract by trans- 

 mitting the rays of light obliquely into the eye so as to get a lateral view 

 of the surface of the capsule. 



From the smallest speck of opacity the disease may be said to grow, often 

 in radiating lines, until at length the whole of the lens is implicated, and 

 thus a number of separate spots, which are detectable in the early stages of 

 the disease, become consolidated into one opaque mass. 



A somewhat different series of changes occurs in the development of 

 cataract by exudation, which seems to affect the whole of the lens at the 

 same time, modifying its transparency very slightly in the first instance, 



Fig. 257.— Capsular and Lenticular Cataracts 



a. Crystalline Lens. I, Capsule of the Lens, c, (Diagram A), Capsular Cataract, 

 c, (Diagram B), Lenticular Cataract. 



causing merely a slight cloudiness which gradually becomes more marked, 

 going on to what is described as a milky condition, and ending in the chalky 

 state which is really complete opacity. It is somewhat remarkable that, 

 to the eye of the examiner, the lens presents a milky appearance, when on 

 post-mortem examination it has been found to present a marked amber 

 tint without the least trace of whiteness in any part. The deposit, how- 

 ever, is sufficiently dense to render the body incajjable of transmitting light. 

 It is interesting to notice that the older writers had very much the same 

 idea of the pathology of the disease as is entertained at present. They 

 referred to the opacity of the crystalline humour, and mentioned the circum- 

 stance of the opaque spots affecting the capsule or some of the layers 



