Abstract
Quantitative eye movement recordings in a patient with suspected multiple sclerosis who had alternating esotropia, horizontal nystagmus and downbeat nystagmus showed occasional monocular macro square wave jerk intrusions and oscillations in the fixating eye during spontaneous monocular fixation, and binocular macro square wave jerk oscillations during the effort to fuse. Base-out (converging) prisms suppressed nystagmus, oscillopsia, and macro square wave jerks, and restored normal binocular function.