THE ADVANTAGE of greater diffusion of an anesthetic solution for retrobulbar injection and nerve block is immediately apparent. After Hoffman and Duran-Reynals1 and McClean2 reported the "spreading factor" of a substance found in the testes of normal rabbits, the use of this substance to increase the spread of anesthetic occurred to me. In 1936 I made a series of injections on rabbits to estimate the spread or diffusion of a solution of procaine hydrochloride with the addition of testicular extract. Ferric chloride was added to the solution to show the extent of diffusion when the tissues were sectioned and stained with Perles' stain. There was a marked increase in diffusion following injections in which testicular extract had been added to the anesthetic solution.
A subconjunctival injection of procaine hydrochloride with testicular extract was also given in one eye of a series of rabbits, and a control injection using
ATKINSON WS. USE OF HYALURONIDASE WITH LOCAL ANESTHESIA IN OPHTHALMOLOGYPreliminary Report. Arch Ophthalmol. 1949;42(5):628-633. doi:10.1001/archopht.1949.00900050638012