Can I change my eye prescription by myself?

My left eye is getting a bit blurrier and it's currently -1.00. Could I just get -1.25 and will it be better for my eyes? I'm too busy to visit an optometrist and need to get a pair of lenses quick!

Thanks for the help(:

No. You do not know why the vision is blurrier. You may have developed an astigmatism. It is best to go to the doctor because there are a lot of reasons why the prescription may have changed.