Unilateral visual neglect (UVN) is the inability of patients, with damage to their left or right cerebral hemisphere, to respond to stimuli presented on the side opposite the lesion. We present a preliminary study on using a HMD-based-eye-tracking system for the assessment of UVN. Normal subjects and patients with UVN were shown two virtual environment (VE) scenes. The subjects were required to identify and count the objects in scene 1, and to identify a clock and tell the time in scene 2. Eye movements of these subjects were recorded during the task. There were differences in the amount of visual field scanned by the subjects and patients. The normal subjects scanned the entire scene and identified all the objects. Patients with left UVN did not scan the left side of the scene and did not report objects on that side. Patients with right UVN scanned only the left side of the scene and did not report objects on the right side of the scene. This study demonstrates the feasibility of using the HMD-based eye-tracking system in a virtual environment for characterizing UVN.

Minimally invasive surgery (MIS), even with its shortcomings, has had a far reaching impact in the field of surgery. During MIS procedures, as the surgeon's hands are remote from the site of the surgery, they do not have a feel of the tissue being manipulated and the forces that should be applied to manipulate the tissue. Studies are being conducted to provide tactile and force feedback of the tissues being manipulated to the surgeon. However, the surgeons are trained in conventional surgery and are familiar with the forces that they apply on the conventional surgical tools. Therefore, before such studies are conducted, there is a need for quantitative comparison of conventional and laparoscopic tools. The purpose of the present investigation was to determine if the forces applied on the conventional surgical forceps are the same as those applied on the laparoscopic forceps during the same procedures. The results of the study showed that the handle and tip forces in laparoscopic forceps were significantly different from that of the conventional surgical forceps ( p ≤0.005). The results also showed that the mean power of the surface EMG measured from flexor pollicis brevis (flexor of the thumb) and the extensor pollicis brevis (extensor of the proximal thumb) while manipulating laparoscopic forceps were significantly different from that measured while manipulating conventional surgical forceps for the same procedure ( p ≤ 0.005).