Background: Fixation disparity is the condition in which the images ofa binocularly fixated object are not imaged on exactly corresponding retinal points, but are still withinPanum's fusional areas. Measurements of objective and subjective fixation disparity have indicated thatsubjective fixation disparity does not indicate the true eye position. However, the effect of the fovealfusional lock (FFL) on the relationship between objective and subjective fixation disparity is stillnot clear. Material/Methods: This relationship was investigated in five subjects. The objective measurementswere made using scleral search coils, and at the same time the Sheedy distance disparometer indicatedthe subjective fixation disparity. Measurements were obtained both with and without an FFL. Results:It was found that without an FFL there was a significant difference (p

Keywords: Eye Movements - physiology, Vision Disparity - physiology, Vision Tests - statistics & numerical data