CR glasses refer to eyeglasses made with lenses constructed from CR-39, a plastic polymer. CR-39 is a common material used in manufacturing eyeglass lenses.
Understanding CR-39 Lenses
CR-39, or Columbia Resin 39, offers a lightweight and cost-effective alternative to glass lenses. However, unlike some other materials like polycarbonate, CR-39 does not inherently block UV rays.
Key Features of CR-39 Lenses:
- Material: Plastic polymer
- Use: Commonly used for eyeglass lenses.
- UV Protection: Requires a UV coating to protect the eyes from harmful sun rays, as noted in the reference material: "...CR39 requires a UV coating to be added to protect eyes from the sun's harmful rays."
- Pros:
- Lightweight
- Cost-effective
CR-39 vs. Other Lens Materials
Here's a brief comparison between CR-39 and other common lens materials:
| Material | UV Protection | Impact Resistance | Weight | Cost |
|---|---|---|---|---|
| CR-39 | Needs Coating | Moderate | Light | Moderate |
| Polycarbonate | Inherent | High | Light | Higher |
