82 



MICROSCOPY OF THE LIVING EYE 



diagrams to represent the sharp optical section of the lens as being 

 in simultaneous focus from front to back. The normal curves of 

 the two surfaces of the lens are shown in Fig. 50, C. 



Observations of alteration of shape of the lens in the act of 

 accommodation are not favourable in the optical section of the 

 normal lens, owing to the wide distance separating the anterior and 

 posterior surfaces ; but a unique case in which a microscopic injury 

 had led to complete solution and disappearance of the entire con- 

 tents of the capsule afforded, by no other means than slit-lamp 



Fig. 49. — Wide slit-beam (B) and narrow slit-beam 

 (A) through anterior region of the lens showing patho- 

 logical dissolution of a small area of the cortex. 



(Draiving by Theodore Hamblin, Ltd.) 



investigation, very precise and conclusive evidence of the altera- 

 tion of the tension of the capsule during the act of accommodation 

 and under the influence of various drugs (17). 



Slight disturbances in the optical section of the lens are very 

 common in elderly people. Examples of this are shown in Fig. 

 49 ; in B the wide beam is used, and the disturbance in the anterior 

 cortex is evident, whilst in A the same region is shown in thin 

 optical section. The optical shadow-streaks passing back from 

 the disturbed area will be noted. In B the anterior lens capsule, 

 throughout a large area of its illuminated face, is seen in the axis 

 of its specular reflection and reveals the " shagreen " appearance 

 seen when (and only when) the capsule is thus viewed. In many 



