saccadic

Saccadic, relating to saccades, describes the rapid, ballistic eye movements that shift the focus of gaze from one point to another. Saccades are the fastest voluntary movements of the human body, typically lasting about 20 to 200 milliseconds, and are followed by a brief period of saccadic suppression in which vision is reduced. They serve to reposition the fovea, the part of the retina with the highest visual acuity, onto objects of interest to facilitate high-resolution perception.

Saccades come in several forms. Prosaccades, or reflexive saccades, move toward a suddenly appearing target. Antisaccades require looking away from a stimulus, testing inhibitory control. Memory-guided or predictive saccades are directed toward locations remembered or anticipated rather than current targets. Small, involuntary fixational movements known as microsaccades occur during attempted fixation and help prevent visual fading.

Neural control of saccades involves a distributed network. The frontal eye fields and supplementary eye fields, along with the posterior parietal cortex, help generate target location and intention, while the superior colliculus integrates sensory input and initiates movement. The brainstem saccade generators in the horizontal and vertical pathways—the paramedian pontine reticular formation and the rostral interstitial nucleus of the medial longitudinal fasciculus, respectively—provide the pulse with a corresponding step to move the eyes. The cerebellum and basal ganglia refine accuracy and timing.

Clinical relevance includes diagnostic use in neurology and ophthalmology. Saccadic abnormalities can indicate focal lesions or neurodegenerative conditions, such as vertical gaze palsy in progressive supranuclear palsy or impaired antisaccade performance in various disorders. Saccade metrics (latency, velocity, amplitude, and gain) are commonly assessed in research and clinical settings to evaluate oculomotor function.