Optician licenses are a way that some states protect their citizens from the possible harm of eyewear prescriptions being dispensed incorrectly. Licensing is a political and financial issue with many complex layers. Some feel strongly that it is a good thing, others a bad one. That will be yours to decide in time.
Do know that in a state that requires a license, you MUST get a license before independently selling, fitting or dispensing eyewear. To see what your state requires for optician training for their license click on your state in the table above.
Note: An eyeglass prescription or Rx is not a chemical compound or medicine likely to to do harm or lasting damage to an individual.