refraktiva

Refraktiva is a term used in optics and allied fields to describe phenomena, devices, or properties related to refraction, the bending of light as it passes between media of different optical density. In practice, anything described as refraktiva involves changes in the light path determined by Snell's law and the refractive indices of the involved materials. The degree to which light is refracted is quantified by the refractive index and by the optical power of a lens, often expressed in diopters. Focal length is approximately the distance over which parallel rays converge after refraction.

In optical design, refraktiva aspects are central to lenses, prisms, and wavefront-based optics. Materials with higher refractive indices bend light more, enabling compact lens designs. Corrective eyewear and camera optics rely on precise refraktiva properties to form sharp images on a sensor or retina.

In medicine, refraktiva relates to refractive errors of the eye, including myopia (nearsightedness), hyperopia (farsightedness), and astigmatism, as well as presbyopia. Refractive surgical procedures—such as LASIK, PRK, and lens implants—alter the eye's refractive power to reduce or eliminate dependence on corrective lenses. Diagnostics often involve objective and subjective refraction, keratometry, and corneal topography to assess refractive status.

The term is most commonly used in Swedish-language medical and technical literature, but equivalents appear in English-language optics as 'refractive' and 'refraction'.