Plural-use drop-by-drop dispenser for sterile liquid product, particularly for collyrium or other medicinal product or medical device

A plural-use drop-by-drop dispenser for sterile liquid products, comprising a vial for containment of the liquid product and a connector provided with a valve device which is normally hermetically closed by an elastically deformable closing element which can be opened by axial external push for controlled drop-by-drop dispensing of the liquid product contained inside the vial and is successively automatically hermetically reclosable when said external push is stopped, and a cartridge with a tubular tang and sterilizing filter which, when said tubular tang is pushed from outside against said elastically deformable element for its opening for drop-by-drop dispensing of the liquid product and can be successively extracted from said elastically deformable element for its hermetic reclosure at the end of dispensing, wherein said cartridge is provided with an end filter-holding bottom element provided with a drop-by-drop dispensing spout, with elastically flexible converging lips, which open under pressure of the liquid product during the dispensing operation and automatically elastically hermetically reclose at the end of the dispensing operation.