Correct! This is downbeat nystagmus, an oscillation most commonly associated with disorders of the medulla or cerebellum. The offending disorder may be structural—Chiari malformation, tumor, or inflammation—or toxic, metabolic, or degenerative. Its mechanism is not well understood. The nystagmus waveform is jerk, the fast component being in the downward direction. If the nystagmus amplitude is great, patients will often report that viewed objects appear to be moving downward. Why downward? Because during saccades, vision is suppressed, so the patient will see objects as moving only during the slow phase, which is moving upward. As the eyes move up, the retinas move in the opposite direction, so objects appear to move downward. This illusion is called “oscillopsia.” It occurs most prominently in forms of nystagmus that have wide-amplitude slow phases.