In the early days of vision correction, all eyeglass lenses were made of glass. Glass lenses offer exceptional optics. But hey are heavy and can break easily, potentially causing a serious eye injury or even loss of an eye. For these reasons, glass lenses are no longer widely used for eyeglasses.
The first plastic eyeglass lenses were developed in the 1940s. These lightweight alternatives to glass lenses were call CR-39 plastic lenses. Plastic eyeglass lenses are about half the weight of glass lenses. They are relatively inexpensive and have excellent optical qualities. They also are more impact-resistant than glass lenses.
The first lightweight polycarbonate lenses for safety glasses were introduced in the 1970s. Since then, polycarbonate lenses have surged in popularity. They are lighter than regular plastic eyeglass lenses and significantly more impact resistant. Polycarbonate is a great lens material for children’s eyeglasses, safety glasses and sports eyewear.
Trivex, a new lightweight and impact-resistant eyeglass lens material, was introduced in 2001. Trivex lenses are a good alternative to polycarbonate lenses. They are lightweight and have slightly different optical and impact resistance qualities. [Read more about Trivex vs. polycarbonate lenses.]
High-index plastic lenses
In the past 20 years, several different types high-index plastic lenses have been introduced. These lenses are significantly thinner and lighter than regular plastic lenses. They have a higher index of refraction and are available in an aspheric lens design (see below for more about these).