High index lenses absorb all harmful UV light and can be tinted to any shade or color. They are available in both glass and lightweight hard resin. They darken to a moderate shade of grey. A demonstration of these lenses is the best way to learn about their properties. This is the most impact resistant lens material available and are always the lens of choice for young people and other active clients.
Polycarbonate lenses are high index and are usually the lightest, most comfortable lenses.
They absorb all harmful UV light and can be made with ultra thin edges because of their unique strength. For years, glass was the only lens material available and glass still offers superior optics. The most scratch-resistant material, the primary disadvantage of glass is its weight, generally twice that of hard resin. Glass lenses are heat or chemically treated to increase impact resistance. Persons who normally wear bifocals or trifocals can use single vision for distance or near lenses.