A split diopter shot is a shot taken by split-focus diopters as it uses a convex glass attachment to make the camera nearsighted, thus giving a deeper focus on the subject. Crime filmmaker and screenwriter Brian de Palma uses this shot throughout his oeuvre.
It has become a trademark of de Palma to use a split diopter -- allowing the camera to emphasize a subject and plot point during emotional and important moments, more often than not, no words would be uttered. His film "Dressed to Kill" contains 20 split-diopter shots.
Preview image was taken from the video.