In Britain, unlike the U.S., there are two types of opticians: ophthalmic opticians, who can do eye tests and write prescriptions, and dispensing opticians, who make and dispense lenses. Only the latter type is called an optician in the United States.
In the U.S., opticians are allowed only to dispense eyewear. In most states (though not all of them -- Oregon is an example), an optician must be licensed and certified, and must have completed at least a two-year associate's degree in opticianry.