The present invention concerns an organic cavity injection device including an injection cannula for injecting a photo-activatable substance inside an organic cavity at least one element or a plurality of elements configured to control the removal of a resident substance from the organic cavity and simultaneously prevent removal of the non-activated photo-activatable substance from the organic cavity and an optical waveguide for providing electromagnetic radiation inside the organic cavity to the photo-activatable substance to photoactive the photo-activatable substance inside the organic cavity.