What is the convergence reaction? | The pupil reflex

What is the convergence reaction?

The term convergence reaction describes the reflex process of the eye when the focus changes from a distant object to a near object. On the one hand, this results in a convergence movement of the eyes. This means that the pupils of both eyes are directed towards the center line of the head.

On the other hand, a narrowing of the pupils is induced, which regulates the amount of incident light. Furthermore, muscle activity causes a change in the shape of the lens. All this leads to better vision of nearby objects.

What is the indirect pupillary reflex?

The indirect or consensual pupillary reflex describes the reaction of one eye to the illumination of the eye on the opposite side.If one eye is illuminated by a flashlight, under healthy conditions the pupils of both the illuminated and the non-illuminated eye will narrow. This is due to an interconnection in the optic nerve, in which fibers of one eye cross to the opposite side in the so-called chiasma opticum. Thus, each side of the responsible brain stem area receives the information from both eyes. Accordingly, a consensual reaction occurs when light is stimulated.