Before revision: Optical plastics For CR-39: Refractive index (): 1.498 (standard) Abbe number (): 59.3 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.
After revision: Optical plastics Plastic lenses are currently the most commonly prescribed lens, owing to their relative safety, low cost, ease of production, and high optical quality.