Mo. Rev. Stat. § 336.020

It shall be unlawful for any person to practice, to attempt to practice, or to offer to practice optometry, or to be employed by any person, corporation, partnership, association, or other entity that practice or attempts to practice without a license as an optometrist issued by the board. Nothing in this section shall be construed to prohibit a person licensed or registered under chapter 334 whose license is in good standing from acting within the scope of his or her practice or a person licensed as an optometrist in any state to serve as an expert witness in a civil, criminal, or administrative proceeding or optometry students in any accredited optometry school from training in the practice of optometry under the direct supervision of a physician licensed under chapter 334 or an optometrist licensed under this chapter.