Systematic Inspection of the Eye. 329 



With partial posterior synechia the rest of the pupil is found 

 dilated while the attached portion extends inward remaining fixed 

 to the capsule of the lens. If the synechia is complete no dilata- 

 tion whatever has occurred. The edges of the adherent iris 

 extend inward as adherent projectionSj and any exposed portion 

 of the lens is likely to show black points, the seat of previous 

 adhesions that have been broken up. In such cases the periphery 

 of the iris bulges forward from the accumulation behind it of 

 aqueous humor or inflammatory exudate which cannot escape. 

 The discoloration of the iris as the result of inflammation, stands 

 out more definitely under the fuller illuinination. 



Crystalline lens. In exploring the crystalline lens or its cap- 

 sule for opacities (cataracts) oblique focal illumination can be em- 

 ployed to the very best advantage, if the pupil has first been 

 widely dilated by homatropine and cocaine. The light is con- 

 centrated on all parts of the anterior capsule in turn, then in suc- 

 cession on the different layers of the lens at all points and finally 

 on the posterior capsule. The striking reflection from any 

 points of opacity whether pigmentary, gray or pearly white is 

 diagnostic, not only of cataract, but of its exact position — an- 

 terior or posterior, capsular or lenticular. 



Purkinje-Sanson images. If the flame of a candle is passed 

 in front of the eye, at a suitable distance, in a darkened room, 

 and the observer looks into the eye obliquely from the opposite 

 side, he observes three images of the flame, reflected respectively 

 from the front of the cornea, from the anterior surface of the 

 lens and from the back of the lens. The image from the cornea 

 is erect, bright and clearly defined : that from the front of the 

 lens is still erect, but larger and dimmer, because the difference 

 between the index of refraction of the aqueous and lens is 

 very slight :'the third image, which is smaller and clearer than 

 the last, is inverted, because the surface of reflection on the back 

 of the lens acts as a concave mirror. The beginner may at first 

 find it difiicult to make out the image from the front of the lens 

 but with a little care he can do so, and then by moving the light 

 he should cause each image to pass over all parts of the reflecting 

 surface in turn. Any unevenness or opacity at any point of the 

 reflecting surface, will cause the image reflected from it to be- 

 come blurred or diffused as it passes over it and thus, not the 



