The McKee laboratory is dedicated to psychophysical and other non-invasive measurements of normal and amblyopic vision. Our primary interests include normal and abnormal binocular vision, motion processing and contrast sensitivity.
Macular degeneration affects the central retina, often causing asymmetrical damage to the two eyes. How does this asymmetrical loss affect stereopsis — the percept of depth generated by the small separation of image features in the two eyes?
In this project we try to gain a better understanding of what visual strategies people use to gather information in the world.
Eye-hand coordination in AMD
Stereopsis is important for tasks of daily living such as eye-hand coordination. It is best in central vision but is also mediated by the periphery. Previously we have shown that individuals with central-field loss who have residual stereopsis in the periphery perform better at an eye-hand-coordination task. Here we sought to determine what sets the limit of stereopsis, defined as the largest disparity that supports the sustained appearance of depth, in the near periphery in healthy individuals. We used a rigorous method to determine the uppermost limit of disparity. The disparity limit is the point at which the threshold for judging dichoptic separation between the half-images is equal to the monocular width-discrimination threshold. The disparity limit at 10° was a factor of 2–4 times larger than the fovea, regardless of the meridian tested. The increase in the disparity limit with eccentricity was shallow, similar to that of Panum's area. Within this disparity limit, disparity increment thresholds were comparable for foveal and peripheral targets, illustrating the significance and utility of peripheral stereopsis, especially in the absence of foveal stereopsis.