Eyeglass Lenses Materials

CR-39 (Plastic)

This is the most basic of materials. No scratch resistance unless added, no UV protection unless added, but lighter than glass.
Pros: Available in ANY lens style and add on type such as Transition, Polarized, etc.
Cons: Thicker than most materials, chips easily in rimless, heaviest of non glass materials, not shatter resistant unless made to a 3.0mm for safety.
Best Prescription Range: +3.00 to -3.00

Polycarbonate

This is what is now considered the most basic and widely used material. It is a lightweight and compact material.
Pros: Available in MOST lens styles and add on type such as Transition, Polarized, etc. It is shatter resistant, impact resistant, UV protection is inherent in the material, and can be made to a thinner thickness.
Cons: Has a higher ABBE value, chromatic aberration occurs (light is broken up into colors like a rainbow that can be seen on surface). Some higher prescriptions are not as sharp or clear. Can scratch without protection such as a super hard coat. Will react to solvents (cracks that start from the edge and spike in towards the middle of the lens).
Best Prescription Range: +5.00 to -6.00

Trivex

This is a great alternative to polycarbonate in order to keep the benefits of a poly lens without the color distortion or aberration. Still a lighter and thinner lens like polycarbonate, yet does not react with chemicals. Best choice for drilled rimless lenses.
Pros: Available in SOME lens styles and add on type such as Transitions and Progressive.
Cons: Limited availability of Single Vision, ST-28 Bifocal and one Progressive style. Transition is only in grey.
Best Prescription Range: +6.00 to -6.00

1.55 to 1.60 Mid Index

Mid index lenses range from 1.54 to 1.60 index of refraction. The 1.60 used to be considered high index but with newer technologies, this is now classified as mid index. These lenses are a mix of polymers that are compact.
Pros: Available in MOST lens styles and materials. Higher prescriptions can be made more cosmetically appealing.
Cons: The higher the index, the greater the amount of reflected light off the front surface of the lens, reducing light and sometimes clarity. Usually easily corrected by adding a quality anti-reflective treatment.
Best Prescription Range: +8.00 to -8.00

1.67 High Index

This high index lens is the lens of choice for very high prescriptions. It is a material made of mixed polymers that are very dense. This allows less curvature needed to create the correction and thus allows for thinner lenses.
Pros: Available in SOME lens styles and materials. Higher prescriptions can be made more cosmetically appealing. Dense material excellent for drilling.
Cons: The higher the index, the greater the amount of reflected light off the front surface of the lens, reducing the light and sometimes clarity. Usually easily corrected by adding a quality anti-reflective treatment.
Best Prescription Range: +12.00 to -12.00 and up

1.74 High Index

This is the latest technology in lens material to date. It has the same properties as a 1.67 high index but due to it's slightly higher index of refraction, lens thickness is reduced to the thinnest possible edge for high minus and the thinnest center from high plus.
Pros: Most advanced material to date giving the thinnest appearance on very high prescriptions. Dense material excellent for drilling.
Cons: The higher the index, the greater the amount of reflected light off the front surface of the lens, reducing light and sometimes clarity. Usually easily corrected by adding a quality anti-reflective treatment. ONLY AVAILABLE IN SINGLE VISION AND VARILUX ELLIPSE PROGRESSIVE.
Best Prescription Range: +15.00 to -15.00 and up