Visual fixation instability

What it means

A deficit in the ability to fixate eye movements in order to stabilize images on the retina

Eye movements are made several times a second to place and hold images of objects of interest onto the central part of the retina, the fovea, where visual acuity is best. These eye movements fall into two main classes. Saccades are fast and brief movements, reaching peak speeds of hundreds of degrees per second and lasting only tens of milliseconds that quickly shift new visual images to the fovea. Smooth pursuit eye movements are slow and continuous, steadily rotating the eyes to track any motion of the visual target, minimizing the retinal slip and the resulting blur that might otherwise reduce spatial acuity. Between these movements, the eyes are held relatively still. These periods of steady fixation are the result of a dynamic process that appears to be actively controlled by many of the same brain structures involved in the generation of goal-directed eye movements.

Rare diseases that can present with this8

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Instability of ocular fixation