Visual accommodation is the adjustment of the curvature and thickness of the lense of the eye, in accordance with the distance of objects. This adjustment ensures the acuity of the image on the retina, and is very similar to how focus is obtained with a camera. In addition, the eyes are turned in order to keep the image directed at the fovea (an action called convergence), and the width of the pupil is adjusted, which further ensures image sharpness.