Density: 1.31 g/cm3 UV cutoff: 355 nm Plastic lenses are currently the most commonly prescribed lens, owing to their relative safety, low cost, ease of production, and high optical quality. The main drawbacks of many types of plastic lenses are the ease by which a lens can be scratched, and the limitations and costs of producing higher-index lenses. CR-39 lenses are an exception in that they are inherently scratch resistant. Trivex Refractive index (nd): 1.532 Abbe value (Vd): 43–45 (depending on licensing manufacturer) Density: 1.1 g/cm3 (the lightest corrective lens material in common use) UV cutoff: 394 nm Trivex was invented by Edwin C. Slagel and patented in September 1998. Trivex was developed in 2001 by PPG Industries for the military as transparent armor. With Hoya Corporation and Younger Optics PPG announced the availability of Trivex for the optical industry in 2001. Trivex is a urethane-based pre-polymer. PPG named the material Trivex because of its three main performance properties, superior optics, ultra lightweight, and extreme strength. Trivex is a relative newcomer that possesses the UV-blocking properties and shatter resistance of polycarbonate while at the same time offering far superior optical quality (i.e., higher Abbe value) and a slightly lower density. Its lower refractive index of 1.532 vs. polycarbonate's 1.586 may result in slightly thicker lenses depending upon the prescription. Along with polycarbonate and the various high-index plastics, Trivex is a lab favorite for use in rimless frames, owing to the ease with which it can be drilled and its resistance to cracking around the drill holes. One other advantage that Trivex has over polycarbonate is that it can be tinted. Polycarbonate Refractive index (nd): 1.586 Abbe value (Vd): 30 Density: 1.2 g/cm3 UV cutoff: 385 nm Polycarbonate is lighter weight than normal plastic. It blocks UV rays, is shatter resistant, and is used in sports glasses and glasses for children and teenagers. Because polycarbonate is soft and will scratch easily, a scratch-resistant coating is typically applied after shaping and polishing the lens. Standard polycarbonate with an Abbe value of 30 is one of the worst materials optically if chromatic aberration intolerance is of concern. Along with Trivex and the high-index plastics, polycarbonate is an excellent choice for rimless eyeglasses. Similar to the high-index plastics, polycarbonate has a very low Abbe value, which may be bothersome to individuals sensitive to chromatic aberrations. High-index plastics (thiourethanes) Refractive index (nd): 1.600–1.740 Abbe value