ABSTRACT
In keyhole surgery, the site of operation is viewed at a TV monitor. Depth perception is based on pictorial information, perhaps enhanced by motion, while monocular and binocular information convey the monitor’s flatness. Only relative depth can be conveyed and pictorial information can mislead. However, depth perception may be adequate if target tissue is well-separated, with well-defined edges and familiar form. Stereoscopic viewing systems now exist, but are problematic because binocular disparity conflicts with convergence and monocular information. Another strategy to improve precision is to employ individuals lacking binocular function: since there is redundancy in depth information, such individuals seem to compensate.
