One of the most common signs that you need new glasses is frequent headaches. If you find yourself experiencing headaches more often, especially after reading or spending time in front of a screen, it could be due to eye strain caused by an outdated prescription. When your eyes have to work harder to focus, it can lead to tension headaches. Consulting an optometrist for an eye exam can help determine if your headaches are related to your vision and if new glasses are necessary.