American Board of Opticianry (ABO) Practice Test 2026 - Free ABO Practice Questions and Study Guide

CR-39 is the most commonly used plastic material in optical frames primarily due to its favorable combination of optical clarity, lightweight properties, and cost-effectiveness. Developed in the late 1940s, CR-39 has become a standard in the eyewear industry. It offers good impact resistance and can easily be adjusted for prescription lenses, making it a practical choice for both manufacturers and consumers.

This material also provides excellent visual acuity because of its low distortion rates, ensuring that wearers experience clear vision. Additionally, CR-39 can be treated with various coatings, such as anti-reflective and scratch-resistant treatments, which enhance its performance and longevity.

In contrast, while polycarbonate and Trivex are also popular lens materials due to their superior impact resistance and thinner profile, they are typically used in specific scenarios, such as safety glasses or high-activity sports eyewear. Cellulose acetate, on the other hand, is primarily utilized for frame construction rather than lens material, making it less applicable in this context.

Overall, CR-39’s balance of performance and affordability solidifies its position as the preferred choice among optical professionals and average consumers alike.