There were innumerable articles during the past century warning against probing the nasolacrimal duct in cases of dacryocystitis in infancy.
In the cases of dacryocystitis in which early probing was used recovery was prompt, and no untoward results of injury were experienced. In the American or the foreign literature I could find expressed only fears as to what might happen with early probing, and no evidence to substantiate the belief that injury resulted from early instrumentation. In my own cases, and in those of the ophthalmic literature, probing the duct (like pushing a stylet through an obstructed hypodermic needle) cleared the dacryocystitis in most instances with a single probing.
A look at the past .... Arch Ophthalmol. 2007;125(9):1173. doi:10.1001/archopht.125.9.1173