Congenital nasolacrimal duct obstruction is most often due to an imperforate membrane at the valve of Hasner.
obstruction of justice | Bowel obstruction | Parotid duct | Obstruction of justice | Duct tape occlusion therapy | Congenital lacrimal duct obstruction | Bottle en ''col de cygne'' (Swan neck duct) used by Louis Pasteur | bile duct |