Final answer:
Optometrists can prescribe vision corrections in diopters, which measure the optical power of lenses. The precision in both determining prescriptions and manufacturing lenses is high, allowing for accurate vision correction for the majority of patients.
Step-by-step explanation:
Optometrists have the authority to dispense prescriptions for vision correction, which are given in units called diopters (D). Diopters measure the optical power of a lens, with 1 diopter equating to the reciprocal of the focal length in meters (1 D = 1/m). When determining corrections in diopters, the minimum uncertainty and the accuracy with which corrective lenses can be produced are important factors to consider. There are sources of uncertainties in both the prescription and manufacturing of lenses, such as the precision of measuring instruments and the controlled manufacture process. It's noted that the thickness of a lens or the cornea can be finely controlled, enabling normal distant vision for most patients, reinforcing the precision achievable in manufacturing and lens fitting.