A1A Optics

What Type of Lens is Best For You?

  • by: bwatson_optics
  • June 1, 2018

What Type of Lens is Best for You?

Choosing a frame that fits both your face and your lifestyle is important when buying a new pair of glasses, but the most important consideration for new glasses is the type of lens. When buying glasses there are four factors to consider: appearance, comfort, vision, and safety. While the frame affects both appearance and comfort, the lenses affect all four factors. When buying new glasses, it is important to consider lens materials and how they fit with your lifestyle. At A1A Optics we take the time to sit with you and determine what type of lens material will work best for your chosen frame and your lifestyle. We are your vision experts!

Below is a short guide to the types of lens materials available to give you what you need to know when choosing new lenses. This guide covers all types of prescription lenses including single vision and multifocal lenses such as progressives or bifocals.

Glass Lenses

Until the second half of the twentieth century all eyeglass lenses were made from crowned glass. Glass lenses have exceptional optical properties which gives the wearer the clearest, sharpest vision through their glasses. There are, however, some drawbacks to glass lenses. For one, glass is heavy. Heavy lenses can become uncomfortable when wearing glasses for an extended period of time. More important to consider, glass lenses are fragile, making them prone to breakage. This is a headache if the glasses are dropped but is particularly concerning in the event the lenses are impacted by an object while the person is wearing the glasses. For these reasons glass lenses are rarely used in the optical industry these days.

Plastic Lenses

During World War II high strength plastic polymers were developed for various military applications. One of these polymers, CR-39, offers excellent optics and is about half the weight of glass. Originally developed for use in lightweight external fuel tanks for airplanes during the war, CR-39 was introduced to the optical industry shortly after the war ended. CR-39 is lighter and also more impact resistant than glass. These properties, combined with the relatively low cost of the material, make CR-39 a popular choice for eyeglass lenses even today.

Polycarbonate Lenses

Originally developed for high impact applications such as bullet-proof windows for banks, polycarbonate lenses have become increasingly popular in the eyeglass industry. Today the majority of lenses in sunglasses and many prescription eyeglasses are made from polycarbonate. The optics of polycarbonate are not as good as CR-39 or glass, but it is much lighter and superior in terms of impact resistance. Because of this, polycarbonate is preferred for children’s eyeglasses and for safety glasses.

Trivex Lenses

Trivex lenses, introduced in the early-2000s, are as this as than polycarbonate lenses and offer nearly the same amount of impact resistance. In addition to being lighter weight, Trivex lenses offer better optics than polycarbonate.

High-Index Plastic Lens

Over the last couple of decades lens manufacturers have worked to produce thinner, lighter weight lenses. These efforts have resulted in the introduction to high-index plastic lenses. These lenses are thinner and lighter than CR-39 lenses and offer better optics than polycarbonate, although the impact resistance is not as good.

Here are popular eyeglass lens materials, arranged in order of refractive index and lens thickness (pretty good indicators of cost). Lenses are listed in order of thinnest to thickest. Except for the crown glass, these are all plastic materials. This table also indicated Abbe Value. In general, the higher the Abbe Value of a lens material, the better the optics of that lens will be.

Eyeglass Lens Materials
Lens Material Refractive Index Abbe Value Key Features and Benefits
High-index plastics 1.70 to 1.74 36 (1.70)
33 (1.74)
The thinnest lenses available.
Block 100 percent UV.
Lightweight.
High-index plastics 1.60 to 1.67 36 (1.60)
32 (1.67)
Thin and lightweight.
Block 100 percent UV.
Less costly than 1.70-1.74 high-index lenses.
Tribrid 1.60 41 Thin and lightweight.
Significantly more impact-resistant than CR-39 plastic and high-index plastic lenses (except polycarbonate and Trivex).
Higher Abbe value than polycarbonate.
Downside: Not yet available in a wide variety of lens designs.
Polycarbonate 1.586 30 Superior impact resistance.
Blocks 100 percent UV.
Lighter than high-index plastic lenses.
Trivex 1.54 45 Superior impact resistance.
Blocks 100 percent UV.
Higher Abbe value than polycarbonate.
Lightest lens material available.
CR-39 plastic 1.498 58 Excellent optics.
Low cost.
Downside: thickness.
Crown glass 1.523 59 Excellent optics.
Low cost.
Downsides: heavy, breakable.

Courtesy of: Dr. Gary Heiting, O.D., “How to Choose the Best Lenses for Your Glasses,” All About Vision, May 2018, www.allaboutvision.com/lenses/how-to-choose.htm

Comments

  1. by: Thanks for the article post. Really great, thank you!

    June 3, 2018 Reply

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