Final answer:
Contact lenses prescriptions in diopters determine the optical power needed for vision correction. Specifications for the lens order include the lens' radius of curvature, diameter, and index of refraction. Both the prescription accuracy and lens manufacturing can introduce uncertainties affecting the lens effectiveness.
Step-by-step explanation:
When writing up a contact lens order for a soft lens, it is important to specify a variety of parameters for proper vision correction. The prescriptions for vision correction are given in units called diopters (D), which measure the optical power of the lenses. The optical power is defined as the reciprocal of the focal length in meters, with 1 D being equivalent to an optical power of 1 meter-1. For a contact lens prescription, the radius of curvature of each side of the lens and the diameter and index of refraction of the lens should be specified to ensure the correct fit and vision correction.
The uncertainty in diopters when determining vision correction and the accuracy of manufacturing the corrective lenses are influenced by technical limitations. To illustrate, a myopic person with a contact lens prescription of -4.00 D would have a far point—the maximum distance at which objects are seen clearly without correction—that can be calculated using the thin-lens formula and sign conventions for lenses. The power of the tear layer, which acts like an additional lens over the cornea, also contributes to the overall correction and must be considered for an ideal fit.