After the age of 40, the natural lens of the eye loses its ability to focus. Near vision becomes more and more difficult. One cannot prevent the onset of presbyopia: It affects 1.7 billion people worldwide.
As with anyone who sees well at distance, those who have had vision correction surgery will need reading glasses after the age of 40. It is important to understand that refractive surgeries such as Lasik do not cause presbypopia.
It's the normal aging of the eye.
THE NORMAL EYE: The lens focuses near objects to a clear image
THE PRESBYOPIC EYE : The lens can no longer focus on near objects
More information on available Presbyopia surgery.