Polycarbonate lenses are great for people with mild to moderate strength prescriptions. They are much thinner and more lightweight than traditional plastic lenses, are UV protected, and are impact resistant. Polycarbonate lenses MUST be used for half-rim, no-rim, safety, or children’s frames.
High index 1.67 lenses should be used for people with stronger prescriptions, and high index 1.74 should be used for very strong prescriptions. High index lenses are the thinnest lenses on the market. They also minimize eye size distortion for cosmetic appearance. High index lenses cannot be used for half-rim, no-rim, safety, or children’s frames.
To make the best choice for your eyes, we suggest using these guidelines:
Strength of RX……………Use
Up to +/- 4……………Polycarbonate Lenses
+/- 4 to +/- 6……………High Index 1.67 Lenses
+/- 6 and up……………High Index 1.74 Lenses
*People with very strong prescriptions who choose polycarbonate instead of high index may have lenses which are thicker than is desirable.
*People with mild prescriptions may choose high index for a super-lightweight extra thin lens if preferred.
If you have questions, do not hesitate to ask!
About Freeform technology
Freeform is a custom lens technology which we use for all our progressive no-line bifocal lenses, both polycarbonate and high index. It provides the wearer with the largest field of view available to the consumer today. We like freeform so much that we have decided to give it to all our progressive lens customers automatically. It doesn’t cost more than the alternative, but it does have much better quality. Other progressive lenses will work but freeform lenses will widen your field of view, meaning you will not have to turn your head as much, and instead, can move your eyes while reading for a more natural experience.