Refraktionsstabilisierung

Refraktionsstärke, also known as diopter power, is the measure of a lens or optical system's ability to bend light. It is expressed in diopters (D) and is defined as the reciprocal of the focal length (in meters): D = 1/f. For the human eye, the total refractive power is about 60 D, with the cornea contributing roughly 40–43 D and the crystalline lens adding about 15–19 D. The eye's accommodation can alter focal length, primarily by changing the lens curvature to sharpen near objects.

In ophthalmology, refractive assessment begins with objective measurements (autorefractor, retinoscopy) and ends with subjective refraction to determine the best correction. Prescriptions are given as spherical power (for myopia or hyperopia), cylindrical power (for astigmatism), and an axis angle for astigmatism. Typical refractive errors: myopia (negative D), hyperopia (positive D), astigmatism (cylinder), presbyopia (age-related near-vision loss).

Treatment options include eyeglasses and contact lenses that correct the refractive error, or refractive surgery to reshape the cornea (e.g., LASIK, PRK) or adjust lens power (implantable lenses). Refractive changes over time can result from aging, axial length changes, or corneal remodeling. Accurate measurement is essential to avoid blur, eye strain, and inadequate vision correction.