For contacts the FTC contacts rule requires certain prescription verification rules. I'm not aware of anything on the federal level that requires a patient hav

For contacts the FTC contacts rule requires certain prescription verification rules. I'm not aware of anything on the federal level that requires a patient have a valid prescription for eyeglasses. (I've looked, but I've not found any such requirement.) The restrictions appear to be on the state level. Some states prohibit dispensing prescription glasses without a prescription. Other states appear to only regulate what a prescription must contain, and how long it lasts, with no apparent laws around dispensing. (For example South Dakota explicitly does not regulate opticians, so unless there is some federal law I have missed, they can produce and dispense any type of glasses to anyone who asks, but cannot do so for contacts due to the FTC contacts rules.)