Ground and polished glass ophthalmic lenses—including single-vision, bifocal, and progressive designs—are classified here when the substrate is glass rather than plastic or other materials. Glass lenses command a niche premium in the eyewear market for their scratch resistance and optical clarity, though they have largely been displaced by lighter polymer alternatives in high-volume retail. Importers should note that finished prescription lenses may attract FDA scrutiny as medical devices, and classification hinges on whether the lens is mounted (which would shift it to a finished spectacles heading) or unmounted.

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