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| Glasses |
| Glasses or Eyeglases is an optical instrument consisting of a pair of lenses for correcting defective vision. The most common types of eyeglass lenses are single vision, bifocals, trifocals and multi-focals (progressive lenses). Eyeglass lens materials include glass and various types of plastic, including new materials that allow thinner, lighter-weight lenses. Various treatments to the lenses include antireflection coating, photochromic (which darken when exposed to sunlight), polarized and toughened (for safety). |
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