High Index Lenses
High index materials are named because they have a higher index of light refraction. They can accomplish the same optical job that glass or CR-39 does, but with less lens material, making high index lenses thinner and/or lighter than traditional lenses. For those of you that are severely near sighted, high index lenses help avoid having “soda bottle” lenses. Not only are the lenses lighter, but they are also thinner, making them more comfortable to wear and more comfortable for your eyes as they work. Our trained opticians will go over all of your options because there are several. But as a rule of thumb, the higher the index of refraction, the thinner the lens.
- Trivex: This material is the newest in the lens category. It has a mid index, but it is so light that it almost floats on water! It is a great choice for safety for impact resistant eye wear. It also works very well for rimless eyeglasses as it is one of the strongest lens materials available.
- Polycarbonate: The first and still the most frequently used high index plastic is polycarbonate. Polycarbonate was originally developed for fighter jet cockpits. It is very strong, very light, and resistant to scratches and breaking. Safety glasses and most sports lenses are made of polycarbonate. In addition, the American Optometric Association (AOA) recommends polycarbonate lenses for all children.
- Mid-Index: High index materials are classified by numbers. Again, the higher the number, the thinner and lighter the lens. The lower numbers are classified as mid-index lenses. Mid-index lenses are those with numbers such as 1.54, 1.56, and 1.57. These lenses are thinner than glass (1.53), and nearly as strong as CR-39 (1.49), or plastic.
- High-Index: High index lenses, typically ranging from 1.53 to 1.74, are much thinner than regular glass or plastic. Talk with your doctor to decide which high index lens is right for you.