If you need reading glasses to read this, you know what we are talking about.
Presybopia is a natural aging process of the crystalline lens (inside your eye, behind the iris) that controls your focusing system, called accommodation. The lens becomes less flexible around the age of 43 and continues to worsen until about age 55, when the changing levels off. There is no way to prevent presybopia. Bifocals or reading glasses will be necessary to see clearly for near tasks.