Optimum view distance for laparoscopic surgery.
BACKGROUND: Proper visualization of the surgical field without fatigue is essential in laparoscopic surgery and reduces the risk of iatrogenic injuries. One of the important factors influencing visualization is the viewing distance between the surgeon and the monitor. This was the subject of the current investigation. METHODS: For this study, 14 surgeons participated in experiments designed to determine two working distances from a standard 34-cm (14 in. diagonal) cathode ray tube (CRT) monitor: (a) the maximum view distance permitting small prints of a near vision chart to be identified clearly by sight, (b) and the minimum view distance (of a standard resolution chart) just short of flicker, image degradation, or both. The range of the monitor optimal working distance for laparoscopic surgery was extrapolated from these data sets. RESULTS: The maximum view distance allowing identification of detail averaged 221 cm (range, 166-302 cm). The mean minimal view distance short of flicker/image degradation was 136 cm (range, 102-168 cm). The coefficient of variation for the two view distances was almost identical (18% vs 17%, respectively), and a frequency histogram confirmed the normality of the two data sets. Thus, for most surgeons, the extrapolated monitor view distances for laparoscopic surgery using a 14-in. diagonal (34-cm) monitor range from 139 to 303 cm (57-121 in.) for maximal distance viewing and from 90 to 182 cm (36-73 in.) for close-up viewing (i.e., a monitor optimal working distance ranging from 90 to 303 cm (36-121 in.). CONCLUSIONS: For most surgeons operating from a 14-in. diagonal CRT monitor, both the maximal and minimal (close-up) view distances are individually variable, but the surgeon should never be farther than 3 m (10 ft) or less than 0.9 m (3 ft) from the monitor. However, within limits, the maximal view distance increases with increasing monitor size. The limit for close-up distance is 0.9 m, irrespective of monitor size.