Statutory Framework: Practice Act, Definitions, and Scope of Practice
The statute and the rules
Missouri optometry is governed by Chapter 336 of the Revised Statutes of Missouri and by the Missouri State Board of Optometry's rules in 20 CSR 2100. The practice act defines optometry, creates a title-protected license, and delegates administration to the board. Board rules supply operational detail-forms, fees, continuing education reporting, recordkeeping-but a rule cannot enlarge the statutory scope.
A function-based definition
The statutory definition reaches services, not devices. It covers examination and diagnosis of the visual system, prescribing and fitting corrective lenses and contact lenses, low-vision rehabilitation, and treatment of ocular disease with pharmaceutical agents when the optometrist holds the required certification. Surgery is outside the definition, as is the general practice of medicine. The act also protects the titles optometrist and O.D.; using them without a license violates the act even if no patient is harmed.
Reading scope in layers
Ask three questions in order. Does the statute list the activity? Does a board rule regulate how it is performed? Does the licensee hold the specific certification the activity requires? An act can be within optometry yet outside a particular licensee's authority because certification is missing.
Worked example. A patient presents with a red, matted eye. An optometrist with therapeutic certification diagnoses bacterial conjunctivitis and prescribes a topical antibiotic. The diagnosis and prescribing fall within the statutory definition, and the certification satisfies the layered test. An uncertified optometrist may examine and recognize the condition but must refer or co-manage rather than prescribe.
Traps. Assuming scope equals the equipment in the office; treating the optician's tasks (grinding lenses, fitting eyewear) as optometry; assuming the board may authorize surgery by rule; forgetting that title use alone can violate the act.