WHY AREN'T EYEGLASS LENSES MADE OF GLASS ANYMORE?😱
Why aren't eyeglass lenses made of glass anymore?
Eyeglasses were invented over 750 years ago for vision correction. Back then, lenses were made of glass, but this material had serious drawbacks: they were heavy, easily broken, and producing just one lens required days of painstaking hand polishing.
Everything changed with the advent of CR-39—a special transparent resin that, in liquid form, allows lenses to be literally "cast" into the desired shape. This is accomplished by using two curved glass templates, leaving a precise space between them for the future lens. Resin is poured into this space under pressure, after which the blank is placed in an oven for about 24 hours at a temperature of approximately 85 degrees Celsius.
After hardening, the resulting lens is perfectly transparent, weighing almost half as much as glass, withstanding impacts much better, and providing the same high-quality vision. This is why most eyeglasses in the world are no longer made of glass, but rather from modern polymer materials.