I squint whenever I am on the computer. Do I need glasses?

When i am on the computer and trying to read something, i've been noticing i am squinting. My vision doesn't really get blurry, so i don't know why i squint. Also, sometimes if there is a large paragraph written in black on a white background, i can't read it so i have to highlight it blue to read it. I am going to the eye doctor's soon and was wondering if i should bother telling them or not.