best method is the use of nitrate of silver, to be neutralized immediately after with a solution of common salt. By this method one can be certain that the cauterization is localized and is not infiltrated in the adjoining tissues. Energetic cauterizations must be made daily for some time in order gradually to destroy the mucous membrane. Care must be taken, too, that the concentrated solution of silver which forms in the sac during the cauterization does not run through the canaliculi into the conjunctival sac.
If one wish to employ the actual cautery for the obliteration of the lachrymal sac, the galvano-caustic is the best.
An annoying epiphora does not always remain after obliteration of the sac, just as strictures may exist without giving rise to any great inconvenience, provided they do not cause a blennorrhœal inflammation of the mucous membrane.
If rupture of the lachrymal sac occur in chronic dacryocystitis, the opening generally closes under proper treatment, or perhaps spontaneously. Often, however, it shows no tendency to heal; it contracts only slightly, the edges become callous, and a lachrymal fistula is established, out of which pus and tears flow. Especially is this the case when from syphilis, scrofula, or any other cause there is caries of the bony walls of the lachrymal canal. But fistulas of the lachrymal sac occur also without any disease of the bone. In many cases the opening becomes exceedingly small, and if at the same time no blennorrhœa of the sac exist, or very little, the annoyance is very slight.
The first object of treatment is to re-establish the normal passage through the nasal duct. The presence of bone disease demands, besides the local treatment of the diseased bone, of the mucous membrane, and of the strictures, treatment of the existing dyscrasia. Especially is the use of iodide of potassium often indicated in these cases.
If there be no bone disease, it is well, in addition to the probing, to touch the walls of the fistula with nitrate of silver. If the duct below the fistula be obliterated, and if there be considerable blennorrhœa of the mucous membrane, the question of the cauterization of the sac arises. Capillary fistulas are best left untouched, since when there is absolute impermeability of the lachrymal canal the closure of the fistula will probably not improve the condition.
Spontaneous obliteration of the lachrymal sac occurs quite rarely
