Final answer:
When looking at a near object, the eyes turn inward in a movement called convergence, which is not through the optical centers of the lenses. This is critical for proper depth perception. Specific vision issues like nearsightedness and farsightedness affect how different focal points are perceived.
Step-by-step explanation:
When a person looks at a near object, the eyes turn inward and are no longer looking through the optical centers of the lens. This movement, known as convergence, allows both eyes to focus on the object and is necessary for depth perception. Convergence is accomplished by the action of the extraocular muscles pulling the eyes toward the midline.
For a nearsighted person, whose eyes have focal points between the lens and the retina, nearby objects are clear while distant ones are blurred. Conversely, a farsighted person has eyes with focal points beyond the retina, meaning nearby objects are blurry, and they can see far-off objects more easily.