Eye Association

EYE ASSOCIATION, the coordinated work of both eyes, leading to the fact that the images obtained in each eye merge with each other and form one common picture. For this, such an eye setting is necessary that upon fixation all individual points of the image obtained in the eyes fall on the corresponding points of the retina (associated points). This is achieved by the associative innervation of both eyes, i.e., with any movement of the eye, the corresponding (associated) muscles of both eyes are excited simultaneously, for example, when looking to the left, the external rectus muscle of the left eye and the internal rectus muscle of the right eye. Thanks to such an Association, both eyes form (in the expression of Hering) as if one common organ. Associated eye movements. All eye movements are of the nature of associated movements and possess a common associated innervation. Among these movements one can distinguish simple eye movements (upward, downward, to the right and to the left), eye movements during convergence and rotational eye movements. To this last type of associated eye movements must be referred the phenomena of "counter-rotation of the eyes" (Gegenrollung) with tilts of the head, which have great physiological significance. Thanks to their associated innervation, the eyes with such tilts of the head preserve their location in space unchanged, so that the images obtained by both eyes from any point of space continue to fall in these cases as well on the associating points of the retina. Convergence phenomena occur with the participation of both internal muscles of the eye, which work as antagonists during simple eye movements. During convergence, in contrast to simple associated eye movements, the axes of both eyes do not remain parallel, but take a converging direction (see drawing). Convergence phenomena are closely connected with the phenomena of accommodation of the eye (see).