If you have a single-vision prescription (glasses to see far away or close up), you can generally get by with CR-39 lenses. They can be inexpensive—we found them for $29 to $149—but they can look thick with stronger prescriptions. A more durable, thinner, lighter, and more popular option is polycarbonate lenses, which we found for $9 to $205.

Polycarbonate lenses are a good choice for people with higher prescriptions. These lenses are thinner, more lightweight and stronger than plastic. However, the optical quality is lower than CR-39, and they are easily scratched.

CR39 is not usually the best choice for rimless drill-mount eyeglasses. The superior impact resistance of polycarbonate and Trivex materials are preferred over CR39 for children’s glasses and applications where safety is a primary consideration for the eyewear.

The types of lenses you choose can make a big difference in the quality of your eyeglasses. Depending on what your eye doctor advises, some people can get along just fine with basic plastic CR-39 lenses, while some may want to consider thinner and pricier polycarbonate or high-index types, which may be more appropriate for stronger prescriptions.