There are many factors to consider when choosing the correct lens material.
CR-39 plastic lenses are the most affordable and commonly used lens, they offer very good optics but are not recommended for semi rimless or drill mount frames. They are also thicker and heavier than alternative materials so if you are nearsighted and have a prescription over -3.00 diopters we would suggest something with a higher index to reduce lens thickness and weight.
Polycarbonate which was introduced in the 1970's for safety glasses is lighter and significantly more impact-resistant than CR-39 plastic and a great material for kids and active adults. It also works great in semi rimless and drill mount frames.
High-index plastic lenses are thinner and lighter than other eyeglass lenses, a number of lens manufacturers have introduced them over the past 20 years. These lenses are thinner and lighter than CR-39 plastic lenses because they have a higher index of refraction. This lens material is also suitable for semi rimless and drill mount frames.
All three of these lens materials can come in photo sensitive (photochromic) and darken with the presence of UV light. We also always recommend an anti-reflective coating that stops bad reflections off of the lens surface and allows more light to pass through. Giving you the best anti glare vision possible. These coating also resist oil and water as well as dust.
