You need a valid prescription. If you do not have one with you, we can call your eye doctor for you (select the option at checkout), or you can call yourself and ask for the details of your eyeglasses prescription (not your contact lenses prescription). By law, your eye care professional is required to give you this information. If your prescription has expired, you should get an eye exam and make sure to leave with a fully-detailed prescription that includes your PD measurement (the distance between your pupils measured in millimeters).