The material a lens is ground from has little impact on its correction capabilities but it can have a major impact on eye safety and your lifestyle. You have two basic choices:

Plastic lenses

Plastic is the most common material used for eyeglasses today. It’s lighter and more impact-resistant than the older-style glass lenses, and easier to tint. It scratches more easily than glass, but scratch-resistant coatings can minimize the damage.

Options in plastic include high-resin plastics and high-index plastics, like polycarbonate, which are ideal for strong prescriptions. Polycarbonate lenses are thinner, lighter and more attractive than traditional high-powered lenses, although they do create a bit more distortion. Polycarbonate is also the strongest lens material made, so it’s the best choice for safety glasses and sports goggles. Active kids should be fitted with polycarbonate eyeglasses to protect them from accidental eye injury.

Glass lenses

As the name "eyeglasses" implies, glass was the world’s primary lens material for hundreds of years, and some people still prefer it. Glass lenses can be twice as heavy as plastic and much more breakable. But, they provide the clearest possible vision and they’re much more resistant to scratches, so people who have a tendency to scratch their lenses often prefer glass. Your ophthalmologist can advise you on whether glass lenses are appropriate and safe for your lifestyle.

Photochromatic lenses

Photochromatic lenses automatically darken in sunlight and lighten when indoors. They are a good option for people who don't like to switch from regular glasses to sunglasses. Photochromatic lenses are available in both plastic and glass. One important factor to remember is that photochromatic lenses do not darken much inside cars, since the windshield blocks many of the light rays that trigger color change.

Plastic photochromatic lenses are not the same as sunglasses. They lose their ability to darken after several years. The degree of darkening will differ depending on the type of plastic photochromatic lenses purchased.