If you need a prescription and not just off the shelf readers - Ask the optometrist to give you the pupillary distance for what you use the glasses for - either reading or distance. THEN you ask for a copy of the prescription so that you can use it to buy glasses online. Without the pupillary distance measure, you're on your own to figure out that important piece to how your lenses should be made for your eyes. I've had shitty optometrists refuse to do a pupillary distance measure ('we don't do that') unless I buy the glasses from them in which case they do magically do that since you can't order glasses without it (but still don't write it onto your prescription). Their glasses were $200 and up for basic ones vs. look at cheaper sources like zenni where you can get frames for much less if only you had that damned pupillary distance number for each eye, and zenni I think tries to help you by providing instructions on how to measure yourself which is still difficult. Good part is that once you have your measure for reading or for distance you can keep it safe and use it thereafter, unless in the future you come down with a disease that permanently bulges your eyes out crossed.