How to Tell If Your Glasses Prescription Is Wrong

A prescription that’s slightly off doesn’t usually announce itself clearly — it tends to show up as a vague sense that something isn’t quite right, which makes it easy to live with for longer than necessary before realising the glasses themselves are the problem.

Common signs

Headaches that reliably show up after reading, screen work, or driving are one of the more common signs, especially if they ease once you take the glasses off. Eye strain or fatigue that builds through the day, needing to squint to bring things into focus despite wearing your glasses, and a general sense of visual “effort” that wasn’t there before are all worth paying attention to. Some people also notice mild dizziness or nausea, particularly with a new prescription that’s meaningfully different from the last one.

Why this happens even with a “correct” prescription

A prescription can be technically correct on paper and still feel wrong if the lenses aren’t fitted properly — if the optical centre doesn’t align with where your eyes actually sit, or if a progressive or multifocal lens hasn’t been fitted to account for your specific frame and face. This is why two people with an identical prescription can have completely different experiences depending on how well the glasses were actually made and fitted, not just what the numbers say.

What to do about it

If symptoms persist more than a week or two — genuine adjustment periods for new prescriptions, especially progressives, are normal and usually settle within days — it’s worth going back to get it checked rather than assuming you’ll simply get used to it. A prescription that never quite feels right usually isn’t going to fix itself, and continuing to strain against it isn’t doing your eyes any favours in the meantime.