Glasses lenses: Overview

The type of lenses in your glasses play a big role in your vision, comfort and safety when wearing eyeglasses. And buying the best lenses for your glasses is not an easy task. There are many different types of eyeglsass lens materials and designs, and each has its own features, benefits, and cost.

The lenses you choose for your glasses influence four factors:

• Vision

• Comfort

• Appearance

• Safety

The following information will help you buy eyeglasses lenses wisely. It applies to prescription eyeglass lenses that correct nearsightedness, farsightedness and astigmatism. It will also help you choose the best progressive lenses or other multifocal lenses if you have presbyopia.

Eyeglass lens materials

Glass lenses

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.

Plastic lenses

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.

Polycarbonate 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 lenses

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).

Comparing lens materials

Here are popular eyeglass lens materials, arranged in order of refractive index and lens thickness (pretty good indicators of cost). Except for the crown glass, these are all plastic materials.