Whenever you go for eye check up after a quick evaluation of your eyesight the task of choosing which pair are right for you begins. Picking up suitable frames for your new prescription is pretty easy because you know which style will suit you best according to your personality and interests but choosing reading glasses is another story. One of the preferred lens types in market are CR39 and Polycarbonate lenses; so which ones you will choose?
Following information will help you to understand main differences between Plastic (CR39) and polycarbonate glasses:
• CR-39 or Normal Plastic: This material is used for prescription for most glasses because of its light weight construction and its property of showing high resistance towards chemicals. CR39 lenses have average weight that is nearly half that of other glass lenses. Although its impact resistance is calculated to be greater than glass but it falls behind polycarbonate in this respect, which are more useful in situations where impacts with the lenses may occur. With this analysis CR39 lenses are not recommended for motorcycling or other active sports activities. However, CR39 does possess high scratch resistant properties it still demands more care and must be handled properly.
• Polycarbonate: It is a kind of impact resistant material and lenses made up of Polycarbonate have impact resistance ten times more than that of normal plastic lenses. This is the main reason for the use of polycarbonate lenses in sports activities as well as motorcycling. Even though this material possesses high impact resistanc it should not be considered to be indestructible; and if it does break it will tend to shatter into large pieces whereas CR39 smashes into small pieces comparatively thus it becomes less hazardous to eyes. Polycarbonate lense also have a thinner construction compared to CR39 and they still offer better protection form UV rays and can stop almost 99.9% beams from sun. Polycarbonate material is also good choice for those who work on computer for long hours and have more exposure to fluorescent lights.
Generally polycarbonate glasses are coated with additional scratch resistant layer but still have thinner appearance and thus are more comfortable to wear for long time.
Some basic comparisons between CR39 and polycarbonate materials are:
Plastic or CR39:
- It possesses less weight as compared to glass; typically, half the weight.
- This material is resistant to solvents.
- With this material there are huge choices for tinting and coatings.
- This is considered to be strongest material with high impact resistance.
- Can have additional coatings for enhancement of scratch resistance.
- Have high capabilities for UV rays protection.