title: Development of variable- focus lenses and a new refractor.
abstract: This paper traces the events that led to the development of the variable-focus lens, the variable-power astigmatic lens, and the principle of remote refraction and "phantom lenses." These developments formed the basis for invention of a new subjective refractor-the Vision Analyzer- whose novel design and rapid operation are described.
mesh_terms: D001251:Astigmatism / Q000175:diagnosis; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans; D007909:Lenses; D008433:Mathematics; D008722:Methods; D055095:Optics and Photonics; D009907:Optometry / Q000266:history / Q000295:instrumentation*; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis