With the Lancaster Red-Green Test, both the red and green targets are linear, and goggles of red and green filters are worn by the patient, with the red filter worn over the right eye. An examiner project one of the flashlights. The patient is asked to superimpose a green line projected from his flashlight onto a red line projected on the test screen from the examiner's flashlight. Again, the examiner moves the projected line of red light until all nine diagnostic positions of gaze have been evaluated. Horizontal, vertical, and torsional deviations can be identified and quantified after the patient's responses are correlated to the examiner's target placement. After the test is completed with the right eye fixating, the flashlights are exchanged
