SHINING A NEW LIGHT ON GASTROINTESTINAL ENDOSCOPY: A RANDOMIZED, CONTROLLED STUDY EVALUATING THE EFFECT OF GREEN LIGHT VERSUS DIM LIGHT ON PERFORMANCE IN THE ENDOSCOPY SUITE

BACKGROUND
The advent of laparoscopic surgery has led to the adoption of green overhead lighting in operating rooms. Green light is purported to minimize glare on video screens, while still facilitating other tasks in the room that are difficult to accomplish in dim light. Data regarding the effect of green light, however, is lacking. Gastrointestinal endoscopy is traditionally performed with overhead room lights off (dim light). Our aim was to evaluate the effect of green light versus dim light on the performance of several common tasks in the endoscopy suite.

METHODS
We conducted a randomized, controlled study comparing image classification on video monitors and the performance of multiple physical tasks in the endoscopy suite using green light and dim light (Figure 1). Eight endoscopists were randomized into two groups. Group 1 started in a room with green light followed by dim light, while Group 2 started in a room with dim light followed by green light. Participants were asked to identify GI polyps, stones and object colors. They watched a video consisting of 35 colonoscopy clips with or without diminutive polyps and 20 fluoroscopy images with or without biliary stones shown in rapid sequence. They were then shown different-colored anesthesia medication tapes and endoscopic tools. Next, participants performed a series of tasks: setting up an endoscope, passing biopsy forceps, removing a simulated biopsy sample from forceps, and threading a biliary wire into a cannula. During the second light condition, the order of video clips was changed. We recorded polyp and stone detection rate, accuracy of color detection, time to complete tasks, eye strain, as well as the National Aeronautical and Space Administration Task Load Index (NASA-TLX), a quantitative survey of physical and mental workload.

RESULTS
The performance of all physical tasks was significantly faster and NASA-TLX was significantly lower using green light compared to dim light (Figure 2). Polyp and stone detection rates were not significantly different. Eye strain, however, was lower under green light (8.8±7.1 vs 3.5±3.4; P=0.047). Color detection of objects in the room was significantly better under dim light compared to green light. Instrument color on monitors, however, was not affected by room light.

CONCLUSION
Performing physical tasks in the endoscopy suite using green light is faster and easier compared to dim light. Green light does not appear to affect monitor visualization while also resulting in less eye strain. Color detection of objects in the room, however, may be impaired by green light. These findings suggest green light may augment performance and improve comfort in the endoscopy suite.