High Index Lenses
Compared to lenses made with CR-39 plastic or even polycarbonate, high index lenses are expensive. Because of their cost, it's only natural that you would want to keep your high index lenses for as long as possible. Of course, the same is true for the frame as well. The longevity of your high index eyeglasses comes down to your selection of protective coatings for the lenses, your frame selection, and your use and care habits.
Anti-Scratch Protective Coating
High index lenses are made from high-refractive-index polymers. In other words, they're made from plastics. Compared to glass, plastics are soft and have a poor scratch resistance. If you drop high index glasses, place them in the sand, or wipe grit from them with a dry cloth, you will likely scratch them. Over time, large and small scratches will accumulate on the lens surfaces …show more content…
While they do a good job of minimally impacting your appearance, they are relatively weak at the attachment points of the frame with the lens. A lot of mechanical stress gets concentrated at these points. And the frame can break there from abuse such as placing the glasses in a pocket or dropping them. A frame that completely encloses the lens rim is a stronger design. Note that rimless glasses can last a long time, but require a high level of care.
While there are a number of durable frame materials, two notable ones are nylon and flexon. Nylon is a lightweight plastic that's flexible and strong. Nylon frames are generally more flexible than those made of metal and are available in many colors. However, they aren't as strong as metal and are weakened by long-term exposure to sunlight. The chemical bonds within nylon also break down with age.
Flexon is a titanium nickel alloy metal that's also lightweight, flexible, and strong. What makes this metal unique is its ability to return to its original set shape after bending or twisting it. It essentially has a kind of built-in
Anti-Scratch Protective Coating
High index lenses are made from high-refractive-index polymers. In other words, they're made from plastics. Compared to glass, plastics are soft and have a poor scratch resistance. If you drop high index glasses, place them in the sand, or wipe grit from them with a dry cloth, you will likely scratch them. Over time, large and small scratches will accumulate on the lens surfaces …show more content…
While they do a good job of minimally impacting your appearance, they are relatively weak at the attachment points of the frame with the lens. A lot of mechanical stress gets concentrated at these points. And the frame can break there from abuse such as placing the glasses in a pocket or dropping them. A frame that completely encloses the lens rim is a stronger design. Note that rimless glasses can last a long time, but require a high level of care.
While there are a number of durable frame materials, two notable ones are nylon and flexon. Nylon is a lightweight plastic that's flexible and strong. Nylon frames are generally more flexible than those made of metal and are available in many colors. However, they aren't as strong as metal and are weakened by long-term exposure to sunlight. The chemical bonds within nylon also break down with age.
Flexon is a titanium nickel alloy metal that's also lightweight, flexible, and strong. What makes this metal unique is its ability to return to its original set shape after bending or twisting it. It essentially has a kind of built-in