Okla. Stat. tit. 18 § 817
This act shall not apply to any persons within this state who prior to the passage of this act were permitted to organize a corporation and perform professional services by the means of such corporation, and this act shall not apply to any corporation organized by such persons prior to the passage of this act; provided, however, any such persons or any such corporation may bring themselves and such corporation within the provisions of this act by amending the certificate of incorporation in such a manner so as to be consistent with all of the provisions of this act and by affirmatively stating in the amended certificate of incorporation that the shareholders have elected to bring the corporation within the provisions of this act.
Okla. Stat. tit. 18, § 817