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Density: 2.56 g/cm³ (the heaviest corrective lens material in common use, today) UV cutoff: 320 nm [permanent dead link] Glass lenses have become less common owing to the danger of shattering and their relatively high weight compared to CR-39 plastic lenses.
A piece of CR-39 manufactured for radiation detection. Poly (allyl diglycol carbonate) (PADC) is a plastic commonly used in the manufacture of eyeglass lenses alongside the material PMMA ( polymethyl methacrylate ). The monomer is allyl diglycol carbonate (ADC). The term CR-39 technically refers to the ADC monomer, but is more commonly used to ...
FDA classification of soft contact lens materials; FDA lens group Adopted name Transmissibility level (Dk x10-11) Water content Chemical composition I non-ionic low water content: galyfilcon A 60 47% – lotrafilcon A 140 24% DMA, siloxane, TRIS: lotrafilcon B 110 33% polymacon: 7.5 36% HEMA: tetrafilcon 9.0 43.5% HEMA, MMA, NVP: II non-ionic
Lenses are used as prosthetics for the correction of refractive errors such as myopia, hypermetropia, presbyopia, and astigmatism. (See corrective lens, contact lens, eyeglasses, intraocular lens.) Most lenses used for other purposes have strict axial symmetry; eyeglass lenses are only approximately
A corrective lens is a lens worn on or before the eye. They are used to treat myopia , hypermetropia , astigmatism , and presbyopia . The main article for this category is Corrective lens .
Corrective lens. A corrective lens is a lens worn in front of the eye, mainly used to treat myopia, hyperopia, astigmatism, and presbyopia. The goal is to bring vision up to 20/20 vision or as close to this as possible. Glasses or "spectacles" are corrective lenses worn on the face a short distance in front of the eye.