An exploration of factors that drive vertical vergence movements across the visual field

The vertical misalignment of corresponding features in the left and right eyes' images are known as vertical disparities. They can arise from misalignment of cameras during image capture, projectors during presentation or misalignment of the eyes. The typical response to vertical disparity is an adjustment in the posture of the eyes, called vertical vergence. The range of disparities which elicit vertical vergence movements is unknown. Furthermore, previous research has investigated vertical disparities applied to the whole visual field, possibly masking any differences between regions of the visual field that elicit vergence movements more effectively than others. We determined the maximum disparity that could elicit vergence movements using disparities applied to the full field. We also measured the range of vertical disparities that elicit vertical vergence eye movements at discrete locations in the visual field and found that they drove corrective vertical vergence movements. However, we found no systematic differences across locations in the visual field. and that vergence movements were larger for full screen than for discrete stimuli. Finally, we examined the relationship between vertical vergence and fusion, finding that vertical vergence movements are elicited by diplopic stimuli, consistent with research on horizontal vergence movements