There's some variation in whether online vendors will require a prescription or not. The first one I tried did, so the second one got my money. AIUI there's not

There's some variation in whether online vendors will require a prescription or not. The first one I tried did, so the second one got my money. AIUI there's not a federal law requiring a prescription, but there are many state laws. Often, they make a distinction between positive and negative prescriptions, which is why you can buy reading glasses (to correct farsightedness) everywhere but have much more limited options for distance glasses (to correct nearsightedness). I guess some vendors can't be bothered figuring out which laws apply to a particular sale and just apply the strictest.