Presbyopia

Optical glossary/How eyes focus

The age-related stiffening of the eye's internal lens that makes close focus difficult, typically from the early forties. Not a disease — the reason reading additions and progressives exist.

In more depth

To focus close up, the eye's internal lens changes shape. That flexibility declines steadily from childhood, but only becomes noticeable when the remaining reserve falls below what reading needs — which, for most people, happens in the early to mid forties. Arms held further out, and brighter light, are the first workarounds.

It happens to every eye, including those that never needed glasses, and exercises do not reverse it. The answer is added plus power for near: reading glasses, bifocals or progressives. The addition usually rises for a decade or two before it settles.