s. HOLTH AND O. BERNER. M.-N. Kl. 



no muscle in the periphery of the iris, which is extremely thin here. The 

 peripheral insertion of the dilatator is lacking, the muscle has no functional 

 origin and thus cannot act as the antagonist of the sphincter. 



However rare the congenital miosis may be, I still feel sure that it 

 must be somewhat more frequent than might be expected, to judge from 

 the scanty notes in the literature. The condition may easily be mistaken 

 for annular posterior synechiae after iritis — in spite of this disease never 

 having existed in the case. It is of still greater importance that a 

 congenital pinhole pupil may be mistaken for Argyll Robertson's spinal 

 miosis. In the latter condition the pupil is seldom less than 2 mm. in dia- 

 meter; in the former, as a rule, between 0.5 and i mm. In this congenital 

 miosis the pupil cannot contract either by light or convergence for the 

 simple reason that the pupil cannot become more narrow than it is. 



Axel B., the twin brother of Anna B., the irides of whom were ana- 

 tomically examined in our previous work (Bibl. 6, case c), came to me the 

 29th October 1919. He was more than 52 years, born 28th July 1867. 

 According to the parents his pupils were from birth extremely small like 

 those of his two sisters. He had always enjoyed the best of health; he 

 could not remember any symptom which could imply diseases in the nervous 

 .system. Like his twin sister Anna B. he never suffered from headaches or 

 spasm of accommodation. As for his sight he had nothing to complain of 

 but bad seeing in twilight. He said that in his youth, when he was driving 

 on the highroad by twilight, he had difficulties in steering the horse and 

 they both often ended in the ditch. Now that he lives in town he is mostly 

 indoors, and does not like to go out except in full daylight. He is emme- 

 tropic in both eyes with \' ^= ^ 5 and reads without glasses Jäger No. i 

 at 25 cm. (pinhole pupils: minimal circles of diffusion). The iris in both 

 eyes is an even cinnamon brown, with the radial fibres closelv stretched 

 and not undulating: no circular grooves in the periphery. The right pupil 

 is nearly round, 0.75 mm. in diameter; the left pupil forms a horizontal 

 oval 0.5 >< 0.75 mm. in diameter. After two instillations of homatropin i 

 per cent, in the course of three hours, the right pupil was dilated to 2 x 2.5 mm. 

 and the left pupil to 1.75 2 mm.; he is still emmetropic with V = ^/5, but 

 to be able to read Jäger No. i at a distance of 30 cm. he must now use 

 4- 3.0 D. ; he cannot read without glasses now on account of larger circles 

 of diffusion. During this slight mydriasis the fundus was seen to be normal 

 in the direct image and the refraction stated to be emmetropic. Muscle 

 balance for 5 meters: orthophoria; for 30 cm. : 2^ exophoria. The central 

 colour sense good (Ole Bull's and Stilling's tests); the visual fields were 

 normal for white and colours. Cocain did not dilate his pupils any more; 



