Presbyopia is the age-related loss of close-up focusing ability. When we are young, our eye’s lens is soft and flexible and can change shape easily, allowing the eye to focus on objects both close and far away. As people enter their 40s, the lens becomes less flexible and is unable to focus on close-up objects. Initially the blurring is worse in dim light, which is why many people first realize they have presbyopia when they have difficulty reading a menu.
Later, the fine print in newspapers, magazines and phone books appears blurry. Near vision is most often corrected with reading glasses or bifocals, but refractive surgery can be used to create monovision in people who want correction for close-up vision. See the section on “Monovision” for more information.
With presbyopia, the eye’s lens can no longer change shape to focus on close objects. Images are not in focus by the time they reach the retina.
Reading glasses or bifocals bend the light rays to move the focal point onto the retina.