No optical glass or other kindred products or instruments of vision shall be dispensed, ground or assembled in connection with a given formula prescribed by a licensed physician or optometrist except under the supervision of a licensed dispensing optician and in a registered optical establishment or office. Provided, however, that the provisions of this section shall not prohibit persons or corporations from selling completely assembled spectacles without advice or aid as to the selection thereof as merchandise from permanently located or established places of business. (1951, c. 1089, s. 17.)