Reading glasses have a prescription, and the prescription changes in a predictable pattern, increasing with age, typically by 50 degrees every five years. Generally, after age 60, the prescription stops changing significantly.
Want to know the approximate prescription of your reading glasses?
All you need: Reading glasses, a piece of cardboard, a ruler, and sunlight.
Instructions: Hold the lenses perpendicular to the sunlight, placing the cardboard behind the glasses.
Focusing: Move the cardboard to find the smallest, brightest point of light. Measure the distance from this point to the center of the lens with the ruler. This equals the focal length (unit: meters).
Calculation: Presbyopia ~ 100: Focal Length (meters)
(This method provides an approximate value. For a precise eye exam, please visit a professional optician!)
If you already have presbyopia, forcing yourself not to wear reading glasses will exhaust your ciliary muscles and prevent them from adjusting properly, inevitably worsening reading difficulties and causing symptoms such as dizziness and eye strain, impacting your life and work. This is very unwise. Therefore, get reading glasses as soon as you need them; don't delay. Also, replace your original reading glasses promptly if the prescription becomes insufficient as you age.
Post time: Nov-21-2025