A new lighting device for open surgery of difficult access wounds was designed: the Extender add-on. The performance of the Extender is evaluated and compared with the conventional solutions used in the operating room (OR) on illumination quality. A cylindrical setup was built to measure the distribution of light in a simulated pelvic wound. The light was provided by a head-mounted light, an OR light, and a pair of Extender prototypes. The results showed that the Extender prototypes provided 12.2 lumens inside the wound, whereas the head-mounted light gave 5.7 lumens. The Extenders provided smoothly angular distributed light from 0 degrees to 180 degrees, whereas the head-mounted light and OR light only provided light from 115 degrees to 180 degrees. The Extender prototypes had a promising performance in terms of light distribution. It is expected that a more accurately produced Extender will increase performance in terms of illumination quantity and illumination distribution smoothness even further.