1. A system for determining a point of regard, said system comprising: camera means for acquiring a video image of a first vision means, said first vision means comprising a pupil, a position of said pupil corresponding to said point of regard, and said video image comprising a pupil image; frame grabber means, coupled to said camera means, for accepting video data corresponding to said video image from said camera means and converting said video data to digital pixel data of a given dynamic range so as to provide said digital pixel data as a grayscale mapping of the video image; computer means, coupled to said frame grabber means, for processing said digital pixel data to substantially determine the position of said pupil wherein said computer means includes: memory means for providing an expected area value for the area of said pupil within said video image; means for determining a grayscale threshold value in accordance with said expected area value and grayscale distribution of said digital pixel data; means for segregating said digital pixel data into two separate binary groups as first and second groups using said grayscale threshold value as a discriminator; and means for substantially determining the position of said pupil in accordance with the segregated data; feedback means, coupled to said computer means, for accepting data corresponding to the determined position of said pupil from said computer means and feeding back to said first vision means feedback information representative of the determined position; and support means, connected to said camera means and said feedback means, for fixing the relative physical positions of said camera means and said feedback means.