Your eyes never look at the world continuously

Try it in front of a mirror: look at your left eye, then your right eye, then your left again. You will never see your own eyes move. Ask someone to make the same movement while you watch them, and you will see theirs jump perfectly clearly.

What happens between two fixations is called a saccade, and the brain deliberately erases it. Without this erasure, your world would be a permanent blur; with it, vision gives the illusion of a continuous image, when it is actually made of successive stops.

Word of the day: the eye saccade

A saccade is a very fast, ballistic movement of both eyes between two fixation points, which can reach several hundred degrees per second. It lasts from a few tens of milliseconds to about two hundred depending on its amplitude, and you make an average of three to four per second without consciously deciding on a single one (the visual system in RNP).

During each saccade, the brain triggers saccadic suppression: it sharply reduces visual processing during the movement, then stitches the image from before to the image from after. And it is a predictive system: at the same time as the saccade command goes out, an efference copy is sent that tells the visual areas what they should see after the jump (the efference copy). If the expected image matches, perception stays silent; if it doesn't, a corrective saccade fires immediately.

Alongside saccades there is smooth pursuit, the one you use to follow a passing car or a moving hand. It glides at the speed of the target instead of jumping, but without precise saccades to frame it, it quickly loses its target.

When saccades break down

When saccades lose their precision or calibration, very different functions silently suffer: a reader who can no longer finish a page without fatigue, a child who skips words or line endings, an athlete who no longer reads the field fast enough to anticipate play (how vision influences balance).

Driven by a brain that predicts, saccades are an integral part of the perception-action loop. When they are calibrated, the world seems stable and the environment stays readable; when they break down, the system compensates, and visual fatigue, then postural fatigue, sets in (the oculomotor assessment).

A stable image is a construction of the brain. When it cracks, the whole body works harder.

To test gaze and its links with balance in a simple way, the vestibular guide is free, and if you work with children, so is the children's masterclass.

You are a movement professional: here is the training. You want to take stock for yourself: request an assessment.