Texas Occupations Code - OCC § 351.355. Determining or Measuring Vision

(1) examine the eye to diagnose the presence of a defect or abnormal condition, the presence or effect of which may be corrected, remedied, or relieved by the use of lenses or prisms;

(2) determine the accommodative or refractive condition or the range or powers of vision or muscular equilibrium of the eye;  or

(3) examine the human vision system to determine a departure from the normal, measure the system's powers of vision, or adapt lenses or prisms for the system's aid or relief.