It’s always good to have options. But what happens when there are too many? This is the situation in the eyewear industry today. There’s an overwhelming number of options in frame choices, tints, coatings, and lens materials. Of these option categories, choosing the right lens material is possibly the most confusing. As you look through the pros and cons of the candidates, there’s no overwhelming winner that’s superior in all the qualities (including cost) that go into a good lens.
How do you make an informed choice? By knowing exactly how you will use your prescription glasses and then picking the lens material with the properties that make the best match. Are the glasses intended for mostly indoor or outdoor use? Is the user an adult or a child? How meticulous is the user about taking good care of her or his prescription glasses? By answering these types of questions, the best lens material will become more clear.
You should try to pick a material that best satisfies your requirements before considering lens coatings. Lens coatings make up for the particular deficiencies of a lens material. However, lens coatings cost money, and the cost of multiple coatings quickly adds up. Getting the right lens material will minimize the coatings you will need.
When to Use Plastic (CR-39) Lenses
Plastic is the least expensive lens material. Although it doesn’t quite have the optical quality of glass or the scratch resistance of glass, it’s much lighter and safer. This safety aspect is important because it doesn’t shatter like glass. Glass shards entering the eye can cause severe injury.
If you are using your glasses for indoor reading or computer work, and your prescription level isn’t too high, then plastic works fine. If you don’t want to fuss too much about its care, a protective scratch coating is a good idea. Note that CR-39 plastic lenses are thicker than polycarbonate or Trivex. If thinness is important to you, then you should consider these other two alternatives.
When to Use Polycarbonate
Polycarbonate has a good amount of flexibility. In fact, breaking a thin polycarbonate lens would require bending it back and forth several times. This is the reason for its superior impact strength (about 10 times higher than CR-39) and why it’s used for safety and sports glasses. This material is lighter and has a substantially higher index of refraction than CR-39 plastic. This means the lenses are thinner and lighter. Another important property is that polycarbonate naturally blocks 100% UV light. On the other hand, its optical quality is inferior to CR-39.
Polycarbonate makes sense as an outdoor eyewear material. It’s a good pick for sunglasses, which should have UV protection. On the other hand, CR-39 plastic would require a special UV protection coating for outdoor use. This increases its cost. The optical quality of polycarbonate is good enough for driving, walking, and other outdoor activities. Polycarbonate’s lighter weight and toughness are perfect for athletic activities. However, this material is relatively soft and will require a scratch protection coating.
When to Use Trivex
Trivex has the same advantages as polycarbonate such as 100% protection against UV and superior impact strength. While it’s slightly lighter than polycarbonate, it also has a slightly lower index of refraction. The big advantage of Trivex over polycarbonate is its better optical quality, which means your vision is sharper.
Trivex is a natural for outdoor use, and as sports and safety glasses. If they aren’t darkly tinted, they’re perfectly suitable for indoor home and work use. Although people do use polycarbonate indoors, its sub-par optical quality makes it less suitable for hours of reading and computer use. The downside of Trivex is that it generally costs more than polycarbonate.Prescription glasses and sunglasses are available with plastic, polycarbonate, or Trivex lenses. Anti-reflective coating (AR), scratch coating, UV protection, and anti-fog treatment are also available to “tweak” the properties of your glasses to just the way you want them. If you have questions about getting the right Nike prescription glasses, contact us today.