The ophthalmologist's name should be on the prescription. Along with their address and phone number.
If the optician has a question about the prescription, or thinks it may have been written incorrectly, they can call the doctor. Otherwise there shouldn't be any need to verify it.
You may choose to buy eyeglasses from a seller who's not your eye care provider. If you do, you may want to fax or send the copy of your prescription directly to the seller to expedite the process. In any case, the seller must verify your prescription with your eye care provider before filling your order. But you can start the process by giving the seller certain information about your prescription-for example, the type of lenses, their manufacturer, power, base curve, and diameter.