I never know the cause... I have a vague recollection that the treatment proposed was to re-route my tears elsewhere but this was years ago and as you know I declined. I do remember the doctor tested how patent my tear ducts were but I don't remember the verdict! I think my tears did flow down onto my cheeks but it was more occasional than constant and for that reason I wasn't keeping track of the frequency. It was probably gradual but the entire issue only lasted a month or so that I remember. I'm sure there was no inflammation or stinging involved. The tears were like tears you would experience from crying.