For labs focused on delivering high-quality eyewear, CR-39 lenses offer a reliable balance of optical performance, durability, and affordability. These lenses are a staple for reducing chromatic aberrations and providing scratch-resistant protection, all at a cost-effective price point.
IOT’s advanced lens designs are fully compatible with CR-39, allowing your lab to maximize performance while leveraging this versatile material.
With an Abbe value of 58*, CR-39 has the highest Abbe value of any plastic (organic resin) lens material, guaranteeing minimal distortion from chromatic aberration and dispersion and enhanced off-axis performance.
CR-39 has a refractive index of 1.49.** The higher a material’s refractive index, the thinner the lens can be while still achieving the desired refractive effect.
CR-39 has the lowest refractive index of all plastic optical materials, meaning it is thicker and heavier. However, the Abbe values of the lenses decrease as their refractive indexes increase, resulting in more dispersion in thinner lenses.
* Abbe value is the measure of a lens material’s dispersion of light into disparate wavelengths and is used industry-wide as an indicator of optical quality.
** The refractive index indicates how the speed of light changes when traveling between mediums by dividing the speed of light in a vacuum by the speed of light in a specific lens material.
CR-39, short for "Columbia Resin #39,” is a lightweight, shatter-resistant alternative to glass or mineral lenses. The CR-39 has been the go-to material for basic prescription lenses for many years.
| 1. | Popularity: CR-39 is widely used in many prescription lenses, especially in the European market. It is commonly offered as a basic lens, without any additional features. |
| 2. | Economical: CR-39 is inexpensive to manufacture. |
| 3. | Versatility: CR-39 boasts impressive chemical resistance, allowing it to be used in the manufacture of industrial eyewear. CR-39 also responds well to the dyeing process, lending itself well to sunglass manufacturing. |
| 4. | Ease of production: CR-39 is easier to produce than polycarbonate because of its scratch-resistant properties. CR-39 doesn’t need the additional layer of coating that polycarbonate requires. |
| 1. | Minimal dispersion and distortion: CR-39’s impressive optical performance makes it a favored choice for consumers, especially those concerned with chromatic aberrations. |
| 2. | Scratch resistance: CR-39 is highly resistant to abrasions, reducing the risk of lens damage. |
| 3. | Affordability: CR-39 is typically the cheapest material available to consumers. |
| 1. | Thickness and Weight: With a refractive index of 1.49, CR-39 lenses are thicker and heavier than lenses made from higher-index plastics. This can be aesthetically unpleasing and less comfortable, particularly for individuals with stronger prescriptions. |
| 2. | Impact Resistance: CR-39 is less impact-resistant than newer plastic materials like polycarbonate and Trivex. This makes it less suitable for safety glasses or sports eyewear, where higher durability is required. |
| 3. | UV Protection: Unlike some modern lens materials, CR-39 does not inherently block UV rays. It requires an additional UV coating, which may wear off over time, reducing its protective effectiveness. |
| 4. | Limited Use in Rimless Frames: Due to its brittleness, CR-39 is not well-suited for rimless or semi-rimless frames, as it is prone to cracking under stress, particularly along drill holes. |
CR-39 is often conflated with Polycarbonate, another widely popular plastic lens material. Understanding these differences can help your lab select the best option for your specific requirements.
CR-39 is a thermostable material known for its superior scratch resistance but is less impact-resistant compared to polycarbonate, making it ideal for everyday eyewear but less suitable for safety or sports glasses.
Polycarbonate, a thermoplastic material, is highly impact-resistant and flexible, making it the preferred choice for high-risk environments like safety eyewear and rimless frames. However, an additional hard coating is required to improve scratch resistance.
CR-39 is widely used in Europe, while polycarbonate tends to dominate in the U.S., particularly in applications requiring high impact resistance, as preferred by many insurance providers.
Ultimately, the right lens material depends on your lab’s specific needs and customer preferences. IOT’s lens technologies are compatible with both CR-39 and polycarbonate, ensuring you can offer tailored solutions for any application.
While CR-39 excels in optical quality and affordability, it falls short in impact resistance, thickness, and UV protection. For labs needing thinner, more durable lenses or built-in UV protection, alternative materials like polycarbonate or Trivex may offer better solutions.
At IOT, we provide a comprehensive selection of lens materials designed to meet every optical requirement:
Our technology integrates seamlessly with CR-39 to deliver lenses that meet modern optical demands, including photochromic and anti-reflective coatings. Contact our team to learn about our industry-leading lens design technologies, all available in CR-39 and other plastic materials.