How often do people who wear eye glasses usually keep a prescription?

I've heard that some people wear the same glasses/with same prescription for one whole year.

How frequently prescriptions change can vary depending on 1) how old you are
2) whether you are nearsighted (myopic) and
3) how near or farsighted your parents are
Your glasses prescription (your refraction) can change rapidly/frequently from ages 6-10, then stabilize through your teens,20s, and 30s, and then change again (presbyopia) in your 40s. Later, when people start to develop cataracts (usually late 50s-70s) it can change again. Some eye conditions and diseases (keratoconus, diabetes) can also cause the refraction to change quickly and frequently. Most people DON'T need to change their prescription yearly though.

doctors usually recommend you check your eyes at least once year if you wear glasses or contacts. the reason for this is that your tend to change so the prescription might need to be stronger or in most cases lower. you really dont want to keep the same glasses over a year in case your sight gets better.

I believe when I was in my teens and early twenties, my prescription was valid for two years. Now that I'm thirty, it only lasts a year.

It is up to the doctor to say if the prescription is good for one or two years. It is recommended that you have your eyes checked every year just to make sure everything is healthy and there are no rips, tears, or holes that cant be felt. You can get more than one pair of glasses. I have five different pairs to go with all of my outfits.