American Board of Ophthalmology (ABO) Practice Exam

The lens in the eye plays a crucial role in vision by adjusting its shape to focus light onto the retina. This process is known as accommodation. When viewing objects at different distances, the lens alters its curvature to ensure that light rays are properly focused. For instance, to see something up close, the ciliary muscles contract, causing the lens to become thicker and more rounded, which increases its power to bend the incoming light rays. Conversely, when looking at distant objects, the ciliary muscles relax, allowing the lens to flatten, which is necessary for focusing those light rays correctly on the retina.

While other components of the eye contribute to vision, such as the cornea, which primarily handles refractive power, the lens's specific function is the dynamic adjustment for focusing. It is not responsible for protecting the eye from infection, regulating light entry (which is a function of the iris and pupil), or transmitting visual signals, as these roles are designated to other parts like the optic nerve.