Saccade

Saccades during observation of a picture on a computer screen

A saccade (/səˈkɑːd/ sə-KAHD; French: [sakad]; French for 'jerk') is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction.^[1] In contrast, in smooth-pursuit movements, the eyes move smoothly instead of in jumps. The phenomenon can be associated with a shift in frequency of an emitted signal^{[clarification needed]} or a movement of a body part or device.^[2] Controlled cortically by the frontal eye fields (FEF), or subcortically by the superior colliculus, saccades serve as a mechanism for fixation, rapid eye movement, and the fast phase of optokinetic nystagmus.^[1] The word appears to have been coined in the 1880s by French ophthalmologist Émile Javal, who used a mirror on one side of a page to observe eye movement in silent reading, and found that it involves a succession of discontinuous individual movements.^[3]

^ ^a ^b Cassin, B. and Solomon, S. Dictionary of Eye Terminology. Gainesville, Florida: Triad Publishing Company, 1990.^{[page needed]}^{[ISBN missing]}
^ Gegenfurtner, K. R. (2016). "The interaction between vision and eye movements". Perception. 45 (12): 1333–1357. doi:10.1177/0301006616657097. PMID 27383394.
^ Javal, É (1878). "Essai sur la physiologie de la lecture". Annales d'Oculistique (in French). 80: 61–73.