Why reading gets harder after 40
The lens inside your eye changes shape to focus on close objects. With age it slowly stiffens, a process called presbyopia, and from the early-to-mid 40s most people notice they hold menus and phones farther away, need brighter light to read, or get tired eyes after close work. It happens to everyone, including people who've never needed glasses.
How the near vision test works
Lines of text are printed at standard N-point sizes, the scale eye doctors use for reading charts, at their true physical size after a quick screen calibration. Hold the screen about 40 cm away, roughly the length of your forearm, and tap the smallest line you can read without squinting. Newspaper text is about N8; small print on medicine labels is around N5.
Choosing reading glasses strength
Over-the-counter reading glasses usually come in steps from +1.00 to +3.00. Based on your age and the smallest print you can read, the test suggests a strength to try. Pick the weakest pair that makes text clear at your usual reading distance. An eye exam will confirm the right strength and check that nothing else is affecting your near vision, especially if the two eyes differ.