How can I tell if my eyeglasses aren't the right prescription? What are the symptoms for incorrect lenses?

if you cant see...

just go to the eye doctor and they can help you...

or, if you glasses are over a year and a half old, you will probably need new ones

In my opinion the easy test I use is reading street signs in the distance. The focusing mechanics of the eye should be in a relaxed state for anything over 20 feet. So I believe that the easy test is distant signs for both farsighted and nearsighted. keep the eye relaxed and see how sharp the distant letters are - if not sharp get an eye exam.

Other symptoms could be headache and eyestrain.

see how far you can read letters, on a page, billboard etc. compare both eyes, one at a time, can you see clearer with one vs the other? If you are not sure, go and get your eyes check, your prescription does change over the period of year or longer, i've had a stronger prescription every year since i was 8, it stopped getting worse when i hit 22, it's kinda of plateaued now.

Basically, if you have been wearing them full time for about a week (2 weeks for bifocals/progressives) and something just does not feel right. Walk in to ur doc office have them rechecked sometimes they are jus made wrong. If they are made correctly..than u should get a free appt with the doc to be rechecked. As long as the glasses were purchased recently. If they find u need something diff they should remake ur glasses at no charge. Again, if they were purchased recently.

if things are blurry and if you might get a headache if the prescription is too high.