Refraktiv

Refraktiv, derived from the Latin root “refractus” meaning “bent back,” is an adjective used primarily in optics and ophthalmology to describe phenomena, materials, or measurements related to the refraction of light. In physical optics, a refraktiv medium is one that alters the direction and speed of light as it passes through, a property quantified by the refractive index. The refractive index (n) is a dimensionless number defined as the ratio of the speed of light in vacuum to its speed in the material; values greater than one indicate that light travels more slowly within the medium, causing it to bend toward the normal at an interface.

In ophthalmology, the term refraktiv is associated with the eye’s ability to focus light onto the retina. Refractive errors—myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia—arise when the eye’s refractive components (cornea, lens, and axial length) do not produce a sharp retinal image. Corrections employ refraktiv lenses, such as spectacles or contact lenses, which possess specific dioptric power to counteract the deviation. Refractive surgery, including procedures like LASIK and PRK, reshapes corneal tissue to modify its refractive power permanently.

Refraktiv measurements are performed with devices such as refractometers, autorefractors, and phoropters, which assess the optical power required to achieve emmetropia. In scientific contexts, refraktiv calculations support the design of lenses, optical fibers, and imaging systems, where precise control of light bending is essential for performance.