In a paper published about a year ago, Dr. W. H. Hough1 made the following statement:
That the organisms have not been found as a rule near the blood vessels, but generally in the gray matter at some distance from them, and that salvarsan appears to have a greater predilection for most of the other tissues of the body than it has for nerve tissue, as Uhlmann has shown in his studies of the neurotropic action of this chemical, may explain in part the inefficiency of salvarsan administered intravenously in the treatment of these conditions.
The close analogy of the ocular circulation to that of the brain suggested to me a reason for the pathology of ocular syphilis that had not heretofore, to my knowledge, been applied in ocular therapeutics. Because of the terminal feature of the ocular circulation, the spirochetes were able to take such a position in
SEIBERT EG. SUBCONJUNCTIVAL INJECTIONS OF SALVARSANIZED SERUM IN OCULAR SYPHILIS. JAMA. 1915;LXIV(20):1649-1650. doi:10.1001/jama.1915.02570460025008