Subjects will be fitted with the appropriate correction for a viewing distance of 24 inches and will be instructed to fixate on a target at the center of stimulus monitor. The test will be performed in a dark room to standardized environment luminance, free of visual and audible distractions. The subject will be comfortable seated facing the stimulus monitor. The patient's seated height will be adjusted so the eye stays in a horizontal plane with the center of the monitor. The test will be performed without pupil dilation and subjects will be allowed to blink freely.