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A Luneburg lens (original German Lüneburg lens) is a spherically symmetric gradient-index lens. A typical Luneburg lens's refractive index n decreases radially from the center to the outer surface. They can be made for use with electromagnetic radiation from visible light to radio waves . For certain index profiles, the lens will form perfect ...
Corrective lens. A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye.
Vertex distance. Vertex distance. Vertex distance is the distance between the back surface of a corrective lens, i.e. glasses (spectacles) or contact lenses, and the front of the cornea. Increasing or decreasing the vertex distance changes the optical properties of the system, by moving the focal point forward or backward, effectively changing ...
Web apps are used by a variety of online sellers of eyeglasses where an object of known size, such as a credit card, is needed to assist (size reference) the measurement process. [13] [14] Some mobile apps have eliminated the need for a reference object to make accurate PD measurements by leveraging depth imaging and advanced algorithms now ...
The aim of an accurate intraocular lens power calculation is to provide an intraocular lens (IOL) that fits the specific needs and desires of the individual patient. The development of better instrumentation for measuring the eye's axial length (AL) and the use of more precise mathematical formulas to perform the appropriate calculations have significantly improved the accuracy with which the ...
With prices starting at $60 per frame, prescription lenses included, Pair is already pretty affordable. However, for a limited time, Yahoo Life readers can save 15 percent on any Pair Eyewear ...