Eyeglass lenses tend to scratch with use or neglect. A scratched up pair of eyeglasses can compromise vision and be a source of annoyance. Technology has yet to come out with scratch-free, lenses but most lenses can be treated with scratch-resistant coating to prolong the life of the eyeglasses. Scratch-resistance involves coating the lenses, both front and back, with a clear, hard coating to withstand scratches. A number of lenses work well with scratch-resistant coating to offer both comfort and protection against wear and tear.
While glass lenses tend to scratch less, plastic lenses made with CR-39 plastic make better choices when it comes to scratch resistance. CR-39 plastic is named according to the resin formulation used by the original manufacturer. Not only does CR-39 plastic weigh less than glass, it also offers better ultra-violet protection from the sun, shatters less easily and can be tinted or coated easily. When they are treated with scratch-resistant coating, CR-39 plastic lenses make great choices, as they weigh less than half the weight of glass lenses.
High Index Plastic Lenses
A number of plastic lens materials are thinner and lighter than CR-39 plastic, which offers even more comfort than the standard CR-30 plastic lenses. The higher the refractive index (how effectively the lens bend the light), the lighter the lenses. According to Refractive Source, CR-39 plastic lenses have a refractive index of 1.498, while any high index lenses have a reflective index of 1.523 or higher. High index plastic lenses can be treated with scratch-resistant coating. Most high index scratch-resistant lenses are 50 percent lighter than CR-39 plastic lenses. An eye professional can advise on what type of high index lens material is best for your prescription and budget.
Polycarbonated lenses are also popular choices. Made from polycarbonate, a lightweight plastic that can withstand rough handling, polycarbonated lenses are also impact-resistant. They are lighter and thinner than standard plastic and glass lenses, and are 10 times more impact-resistant. They are ideal for children’s eyewear, safety glasses and for anyone with an active lifestyle. Some come with scratch-resistance already built-in, but you can always ask for scratch-resistant coating at the optometrist’s office.
Buying a pair of eyeglass with scratch-resistant lenses does not guarantee against scratches. Eye professionals advise using care when handling your eyeglasses. Always keep them in a cushioned case when not in use. Wash lenses with warm soapy water and dry or clean them with a soft microfiber cloth.