The present invention relates to a coupling interface between a laser source and a tissue (2) to be treated, characterized in that the coupling interface comprises —a ring (3) including: ⋅a side wall (31), ⋅a proximal end (311) intended to come into contact with the tissue (2) to be treated, and ⋅a distal end (312) intended to receive the end of the laser source; —a window (32) transparent to a laser beam generated by the laser source, said window being mounted in a sealed manner on the distal end (312) of the ring (3) in such a way as to close the distal end (312) of the ring (3).