Abstract: An apparatus for medical treatment by means of laser light includes an optical conducting fiber which has a curved light emission end and includes a core, a cladding arranged above the core for conducting laser light coupled into the optical conducting fiber, and capillaries arranged in the cladding, wherein the capillaries run in a longitudinal direction of the optical conducting fiber at a radial distance from a longitudinal axis of the optical conducting fiber and form a capillary ring when viewed in cross-section, wherein the capillaries have cavities which are separated by bridges which have a width which is smaller than a wavelength of the laser light, wherein the laser light emerges from a forward surface of the light emission end and is transmitted in a direction which runs transverse to a substantially straight longitudinal section located directly in front of a curvature which defines the curved light emission end.