The peristriate area 19 interprets accommodation, and sends signals via the Edinger-Westphal nucleus and the 3rd cranial nerve to the ciliary muscle, the medial rectus muscle and (via parasympathetic fibres) the sphincter pupillae muscle.
During accommodation, the pupil constricts to increase the depth of focus of the eye by blocking the light scattered by the periphery of the cornea.
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 lens then increases its curvature to become more biconvex, thus increasing refractive power.