It shall be unlawful for any such licensee to permit his license to be used by any unlicensed person and shall be a violation of the terms hereof for any unlicensed person to practice or attempt to practice or conduct his business under the rights and privileges conferred upon some other person duly licensed. Notwithstanding any other provision of law, an optometrist may delegate tasks to his assistants working under his direct supervision. As used herein, "direct supervision" means that a licensed optometrist shall be on the premises at all times. Nothing herein shall preclude such optometrist from being absent from the practice for reasonable periods during the working day, such as lunch or other customary, practice-related absences. No contact lenses shall be dispensed during his absence. Provided, however, that under no circumstances will these assistants be allowed to make a refraction for eyeglasses or give a contact lens fitting. Provided, however, nothing herein shall be construed to interfere with the operation of offices in accordance with Section 40-37-290.