fixation
The ability to direct and maintain the visual axis on a target of interest, involving complex neural mechanisms for gaze stability.
Full Definition
Fixation is the process by which the eyes are directed and held steady on a visual target to maintain the object's image on the fovea for optimal visual acuity. Stable fixation requires the coordinated function of multiple eye movement systems including the fixation system itself, which suppresses unwanted saccades, and the vestibulo-ocular reflex, which compensates for head movements. Fixation instability can manifest as square wave jerks, drift, or frank nystagmus, and may indicate neurological disease affecting brainstem or cerebellar circuits involved in gaze control.
Usage
Usage note: Distinguish from visual fixation preference, which refers to eye preference in strabismus.
In Context
- "Fixation was stable centrally with no evidence of square wave jerks or fixation instability." — Oculomotor examination
- "The patient demonstrated poor fixation with frequent refixation saccades during attempted steady gaze." — Neurological assessment