American Board of Ophthalmology (ABO) Practice Exam

What is the term for the ability of the eye to focus on objects at different distances?

1. Accommodation

2. Refraction

3. Adaptation

4. Convergence

The correct answer is: Accommodation

The ability of the eye to focus on objects at different distances is known as accommodation. This process is essential for clear vision at varying distances, as it involves the ciliary muscles surrounding the lens of the eye. When viewing a distant object, the ciliary muscles relax, allowing the lens to flatten, which helps focus light from far away. Conversely, when looking at nearby objects, the ciliary muscles contract, causing the lens to become more rounded and thicker, which increases its refractive power to focus light accurately on the retina. Refraction refers to the bending of light rays as they pass through different media, such as the cornea and lens, which is a fundamental optical principle but does not specifically describe the eye’s ability to focus at different distances. Adaptation typically relates to the eye's adjustment to changes in light conditions, helping the eye to adjust from bright to dim light or vice versa. Convergence is the coordinated inward movement of both eyes toward the nose to maintain single binocular vision when focusing on a near object, but it does not involve the focusing ability of the lens itself. Therefore, accommodation is the precise term for the lens's adjustment in focus that enables clear vision across a range of distances.