BLICKVERFOLGUNG FÜR GESICHTSFELDUNTERSUCHER

A field test apparatus is disclosed which is interactive both in the automated positioning of trial lenses (used to correct the patient's focal distance to the tester hemispherical projection screen) as well as providing automatic gaze direction determination through automated video surveillance of the patient's eye. A moveable trial lens holder is provided. This trial lens holder is remotely moveable horizontally and vertically and carries light sources for illuminating the eye preferably in the infrared spectrum at oblique angles preferably towards the center of the eye from the periphery of the trial lens holder. In the gaze direction determination system, a gaze direction determination infrared source-preferably on the surface of the screen near the center of the screen-generates a gaze direction determination reflection on the cornea of the eye-this reflection being near the apex of a normal spherical cornea. At the same time, provision for the automated video measurement of the center of the eye pupil is provided-preferably including measuring a horizontal chord of the eye pupil, bisecting this horizontal chord, locating the bottom of the eye pupil along the bisected dimension, and thereafter finding the pupil center. The relative position of the gaze direction determination reflection from the cornea and the center of the pupil is necessarily related to the direction of gaze of the eye. This relative position is compared to the relative position that the patient initially had when properly fixated. Change in this comparison value is utilized to indicate a change in gaze direction.