399cervical muscle activity indicating muscle ease [ 103 – 105 ]. The gaze-down technique
not only improves neck and eye discomfort, it may improve performance as several
simulation studies have shown shorter task times and fewer errors [ 46 , 98 ,
121 – 123 ].
The optimal monitor distance for a standard 19-inch monitor is 2.5–4 feet from
the surgeon’s eye which allows for the extraocular and ciliary musculature to be in
its most relaxed state [ 124 ]. However, this distance is dependent on monitor diam-
eter and resolution. Large, high-definition screens may need to be placed slightly
further away [ 114 , 115 ]. During close-up visual activity, the eyes converge and the
lenses accommodate which leads to strain on the eye musculature if close-up activ-
ity is prolonged [ 120 , 125 – 127 ]. Conversely, visual acuity decreases with increas-
ing distance which may result in forward projection of the head to compensate for
Fig. 22.4 Correct monitor
height is shown in the top
image. The top of the
monitor is placed at eye
level and approximately
3 feet away from the
surgeon. Incorrect monitor
height, with the monitor
above eye level, is shown
in the bottom image
22 Surgical Ergonomics