Why one eye can become your aiming reference
With both eyes open, your brain normally combines their slightly different views into one sense of depth. The difference between those views—called binocular disparity—helps you judge how far away objects are. But when a task demands precise alignment, such as sighting along a tool or pointing at a small target, the brain may give one eye’s view more weight. That preference is called eye dominance.
It is not simply a matter of one eye being stronger or healthier. The preferred eye is often the one the brain uses as its main reference for lining up objects, even when both eyes see clearly. Eye preference can also differ by task, and the simple “close one eye, then the other” check is an informal demonstration rather than a diagnosis.
Why the distinction matters
Aiming often involves placing a near reference point—such as a sight or fingertip—in line with something farther away. Each eye sees that near point from a slightly different angle. If the alignment is guided by one eye while the body is positioned around the other, the near reference can appear displaced relative to the target. In sports, this can affect how someone naturally turns their head or stands to look along a line.
The practical lesson is not that everyone must aim with a particular eye. It is that a small change in head position can change which view is doing the aligning. When a target seems to shift as one eye is covered, that movement reveals how much the aiming reference depends on the viewpoint—not necessarily a problem with either eye.
