What is the term for the eye's ability to focus on objects at varying distances?

The ability of the eye to focus on objects at varying distances is known as accommodation. This process involves the lens of the eye changing shape to adjust the focal length, allowing light to be focused properly on the retina regardless of whether the object is near or far. When viewing distant objects, the ciliary muscles relax, causing the lens to flatten. In contrast, when focusing on nearby objects, the ciliary muscles contract, allowing the lens to become thicker and more rounded. This dynamic adjustment is crucial for clear vision at different distances.

Understanding this concept is fundamental because it highlights the eye's adaptability and the importance of the lens's flexibility in maintaining sharp focus across various viewing conditions. The other terms, while related to vision, represent different phenomena: convergence deals with the inward movement of the eyes, refraction refers to the bending of light as it passes through different media, and fusion relates to the brain’s ability to combine the images from both eyes into a single percept.