Systematic Inspection of the Eye. 327 



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 SN-nechia is complete no dilata- 

 tion whatever has occurred. The edges of the adherent iris 

 extend inward as adherent projections, and any expo.sed portion 

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

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

 of the iris bulges forward from the accumulation behind it of 

 aqueous humor or inflannnatory exudate which cannot escape. 

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

 out more definitely under the fuller illumination. 



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

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

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

 widely dilated l)y 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 finallj' 

 on the posterior capsule. The striking reflection from any 

 points of opacity whether pigmentar3% gray or pearly white is 

 diagnostic, not only, of cataract, but of its exact po.sition — 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 obliqueh' 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, becau.se 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 difficult 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 pa.ss over all parts of the reflecting 

 surface in turn. Any unevenness or opacity at an}- point of the 

 reflecting surface, will cau.se the image reflected from it to be- 

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



