What does the "power" refer to on a contact lens prescription?

The term "power" on a contact lens prescription specifically refers to the degree of vision correction needed for the individual. It is expressed in diopters (D) and indicates how much correction a person's vision requires to achieve optimal clarity. This measurement is crucial as it directly affects how well an individual can see when wearing contact lenses and helps to tailor the lens to meet the specific visual needs of the wearer.

Understanding the significance of power is essential for practitioners in determining the appropriate lens prescription. A power that is too low may not provide adequate vision correction, while a power that is too high can cause discomfort and visual distortions. Thus, the correct power ensures that the contact lenses effectively compensate for refractive errors such as myopia, hyperopia, or astigmatism.

The other choices relate to different aspects of contact lens design but do not define "power." The diameter relates to the lens size, the material pertains to the substances from which the lens is made, and the curvature describes the shape of the lens surfaces that impact fit and comfort rather than vision correction directly.