I have an eye test every 1 or 2 years, depending on whether the lenses are still keeping my vision clear. But I seldom actually replace the frames themselves. When you are first recommended to wear glasses, consider choosing a pair of frames which can later allow the lenses to replaced. This is what I have done. When I get a new prescription, I send the glasses off to a reputable online optician together with the prescription and they replace the lenses. While the glasses are being reglazed, I'll use on old pair to keep me going. Replacing the lenses in an existing pair of glasses is cheaper than buying a new pair. And for me, this also saves the chore of choosing a new pair of glasses.