Cal. Bus. & Prof. Code § 2550

Individuals, corporations, and firms engaged in the business of filling prescriptions of physicians and surgeons licensed by the Medical Board of California or optometrists licensed by the State Board of Optometry for prescription lenses and kindred products, and, as incidental to the filling of those prescriptions, doing any or all of the following acts, either singly or in combination with others, taking facial measurements, fitting and adjusting those lenses and fitting and adjusting spectacle frames, shall be known as dispensing opticians and shall not engage in that business unless registered with the State Board of Optometry.