Changes in contraction of the ciliary muscles alter the focal distance of the eye, causing nearer or farther images to come into focus on the retina; this process is known as accommodation.A near object (for example, a computer screen) appears large in the field of vision, and the eye receives light from wide angles.The oculomotor neurons functions to send its axons in the oculomotor nerve, to control the medial rectus, and converge the two eyes.Neurons that are interposed between the afferent and efferent limbs of this circuit and include the visual association cortex, which determines the image is "out-of-focus, and sends corrective signals via the internal capsule and crus cerebri to the supraoculomotor nuclei.This limb includes Edinger-Westphal nucleus and the oculomotor neurons.The main function of the Edinger-Westphal nucleus is to send axons in the oculomotor nerve to control the ciliary ganglion which in turn, sends its axons in the short ciliary nerve to control the iris and the ciliary muscle of the eye.The medial rectus attaches to the medial aspect of the eye and its contraction adducts the eye.
The accommodation reflex (or accommodation-convergence reflex) is a reflex action of the eye, in response to focusing on a near object, then looking at distant object (and vice versa), comprising coordinated changes in vergence, lens shape and pupil size (accommodation).
Convergence is the ability of the eye to simultaneously demonstrate inward movement of both eyes toward each other.
This is helpful in effort to make focus on near objects clearer.
It also includes the supraoculomotor nuclei (located immediately superior to the oculomotor nuclei) that generates motor control signals that initiate the accommodation response and sends these control signals bilaterally to the oculomotor complex.
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co.
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When moving focus from a distant to a near object, the eyes converge.