Why does the eye lens contribute to changes in vision with age?

As humans age, the lens of the eye undergoes physiological changes that significantly impact vision, primarily through two processes: the loss of elasticity and the development of opacities.

Presbyopia

The most common age-related change is presbyopia, which typically becomes evident after age 40. This condition occurs because the lens gradually hardens and loses its elasticity over time. Under normal conditions, the eye achieves focus on near objects—a process called accommodation—by contracting the ciliary muscle, which allows the elastic lens to bulge and increase its curvature. As the lens loses its flexibility, it can no longer change shape effectively to focus on near objects, leading to difficulty with tasks like reading.12

Cataracts

Vision also changes due to the formation of cataracts, which are opacities within the lens. While the lens is normally transparent, age-related processes can cause the internal lens fibers to compress, harden, and lose transparency. This often results in symptoms such as cloudy vision, poor color discrimination, and changes in distance vision. If these opacities become severe, surgical intervention is often required to replace the cloudy lens with an artificial one.3