Most of us will need glasses at some point in their lives and some of us may wonder whether glasses weaken our eyesight.
Struggling to focus on printed matter is an unfortunate sign of ageing. Changes to the lens of the eye as we get older mean we have to move the page further and further away before we can see properly. This condition is called presbyopia and it usually happen by our mid 40s.
If you think your eyesight's got worse since you've started wearing glasses, you're far from alone. But the truth is many eye conditions, including presbyopia, get worse over time by themselves, specs or no specs.
What your specs have done is got you used to seeing more clearly. So when you take them off, the contrasting blurriness is more noticeable.
Glasses don't change the process of presbyopia or other eye conditions. But take them off, and your eyes might seem lazy at mustering any remaining focusing power. That's because the muscles that bend and straighten the lens of your eye haven't worked as hard when your specs have been doing some of the job.
But your glasses haven't made your vision worse. The real problem isn't weak focusing muscles; the real problem is the eye's lens has become less flexible so it can't focus well.
Wearing sunglasses to protect your eyes from UV light might help delay the stiffening of the lens that causes presbyopia.
So if you want to see well throughout life, wearing glasses or contact lenses is pretty much inevitable - and not harmful.