Towards better lighting recommendations for open surgery

Abstract

This study assesses the lighting requirements for operating theatres and the lighting conditions in a specific test case and proposes alternate ways of achieving a favourable visual environment. The hypothesis was that an increased illuminance level from general lighting and lower luminance contrasts between the essential task areas affect perceived lighting quality, visual ability and performance, as well as tiredness of medical staff performing surgical work. The investigation consisted of three parts: a laboratory study, followed by a field study and concluding with a retrospective study. In the laboratory study, each medical staff subject was exposed to four lighting scenarios with three illuminances from the operating light (12 lighting conditions), with no patients present. In the field and the retrospective study, the existing lighting scenario was compared to the highest-rated test lighting scenario (with illuminances more than double). The field study and the retrospective study took place with medical staff working under either the test general lighting condition or the existing general lighting condition. Increased illuminance from the general lighting and a higher correlated colour temperature did not improve the operating staff’s visual ability. However, medical staff rated the change in lighting quality resulting from the increased general illuminance as an improvement in the work environment, both in the laboratory study and in the field study. Medical staff subjects using the operating theatre rated both perceived visual ability and lighting quality higher under the test lighting scenario. Tiredness was also rated lower under that test scenario. Based on the results from this study, general lighting levels of 2000 lx in the periphery of the operating room, 4000 lx surrounding the operating table and 5500 lx on the operating table are recommended by the authors. With reference to the selections made by the surgeons for the illuminance in the operating cavity, it is suggested that the central beam illuminance from the surgical luminaires be between 50,000 lx and 100,000 lx.