Accommodation is the ability of the lens of the eye to change shape, allowing for a change in focus from far to near. The lens, which is flexible, becomes more round to bring near objects into focus and flattens to bring distant objects into focus.
With age, the lens of the eye loses some of its flexibility, reducing the ability to accommodate. This usually starts to affect your near vision around age 40 and is called presbyopia.
Medical Review:Adam Husney MD - Family Medicine & Christopher J. Rudnisky MD, MPH, FRCSC - Ophthalmology