A sterile device designed to transmit cold light via a guidewire into the sinus cavities to provide illumination of the operative site during diagnostic and therapeutic procedures in conjunction with other nasal and sinus devices. It is typically a flexible light cable with a fibreoptic core which tapers at the distal end into a long, thin, probe that is capable of being manoeuvred into the various cavities; the proximal end will attach to an appropriate light source. This is a single-use device.