How do I tell my parents that I need glasses?

Last school year, I also noticed that I could no longer read the writing on the blackboard from the third row. I started copying from my neighbor. Whenever my mom asked me if I could still see, I always lied and said yes because I simply didn't want glasses. But now I'm worried because I'm getting lower grades on quizzes, for example, because I can't read the sentences. And now it's really become clear to me that I need glasses.

Yesterday was my first day of school after the summer holidays, and maybe I could use this as an opportunity to tell my parents that I need glasses. But how should I phrase it, and when?

I'm also afraid that everyone will look at me strangely because they're used to me without glasses. But I don't want to wear contact lenses either.