What condition is characterized by difficulty focusing on nearby objects due to the loss of elasticity in the crystalline lens of the eye?

The condition characterized by difficulty focusing on nearby objects due to the loss of elasticity in the crystalline lens of the eye is presbyopia. This condition typically occurs with aging, as the lens loses its flexibility, making it harder for the eye to change its focus from distant to nearby objects.

As the lens becomes less elastic, the ability to accommodate, or adjust focus, diminishes. Individuals with presbyopia often find that they need to hold reading materials further away to see them clearly, which is a direct result of the lens's inability to change shape adequately for near vision tasks. This condition is a natural part of the aging process and affects almost everyone to some degree as they reach their 40s or 50s.

Other conditions related to vision, such as myopia (nearsightedness), astigmatism (irregular curvature of the cornea), and hyperopia (farsightedness), stem from different optical issues and do not primarily involve the loss of lens elasticity or the specific focusing difficulty tied to age. Therefore, presbyopia is clearly the condition that matches the description provided in the question.