ENDOGENOUS INFECTIONS 361 



In these cases, just as in many ectogenous infections of the 

 cornea, the clinical appearance of a ring abscess results from the 

 concentrated action of the toxin from behind on the central layers of 

 the cornea. 



In benign and milder cases of metastatic ophthalmia we naturally 

 can have minor corneal affections. 



That peculiar affection of early life the ulcus eornese internum, 

 which appears clinically related to keratitis parenchymatosa, and 

 leads to secondary hydrophthalmos, is referred by E. von Hippel 1 to an 

 endogenous infectious action from behind. The type of vims which 

 causes the lesion is not determined. It cannot be any of the known 

 pyogenic organisms, as these could not fail to produce severe intra- 

 ocular changes if they acted so destructively on the cornea. (The 

 interesting researches of Leber and Addario 2 show that intra-uterine 

 metastatic changes can occur in the eye. They found a suppurative 

 inflammation, apparently commencing from the retina, in the eyes of 

 two newly-born goats, and in the exudate there were many Gram- 

 positive bacilli, showing polar staining, which from their shape 

 evidently belonged to the group of the pseudo-diphtheria bacilli.) 



Keratitis parenchymatosa 3 is a chronic endogenous inflammation 

 of the cornea, and is much more important ; the most important factors 

 in its etiology are syphilis, tuberculosis, and leprosy, and these are so 

 important that it is a matter of dispute whether in those cases which 

 have been ascribed to other agencies a combination with syphilis or 

 tuberculosis was not present. 



We have to consider whether this condition is due to a pure toxic 

 action or to an infection of the cornea. The old idea, which was 

 supported by Panas, that the whole affection was purely toxic, and 

 the result of a general dyscrasia, without the deposition of any 

 organisms in the eye, was shown to be unlikely when Michel, Bongartz, 

 Bach, Zimmermann, Burstenbinder, and E. von Hippel proved that 

 in the tubercular form actual tubercles were formed in the cornea. 4 

 The examination of the syphilitic cases for Spirochteta may throw 

 light on this subject. Stargardt, Bab, Peters, and Bomer 5 have 

 demonstrated the Spirochatce by the silver method in the cornese 



1 'Das Ulcus Corner Internum,' Festsch. f. A. ran Hippel, Halle (Marhold), 1899.' Peters 

 (K. Jf.f. A.) considers that the condition is due to a failure in development. Hippel's 

 findings can quite well have been due to inflammation. 



2 A. f. 0., 1899, xlviii., 1, p. 192; cf. also Hoppe, A. f. A., xliv., p. 225. 



3 For literature, see sec. ' Path, des Auges,' Lubarsch-Ostertag, 1894-99, Axeiifeld ; 

 1900-1905, Stock ; also Dissertation by Rabiger, Berlin, 1906. 



4 Wehrli considers that ' nodular opacity of the cornea ' is a tubercular form of lupus 

 (Z.f. Z., 1905, xiii. 322, and K. Jf.f. A., 1906, Bd. ii. ; also Heidel. Congr., 1907). 



5 See Ophth. Geseltsch., Heidelberg, 1906. 



