The lenses you choose for your eyeglasses — even more than frames — often will determine how happy you are with your eyewear. When getting your spectacles, the frame you choose is important fashionably to both your appearance and your comfort when wearing glasses. But the eyeglass lenses you choose influence four factors: appearance, comfort, vision and safety. A common mistake people often make when buying eyeglasses is not spending enough time considering their choices of spectacle lens materials, designs and coatings.
The information below applies to all prescription lenses for glasses whether single vision lenses to correct nearsightedness, farsightedness, and/or astigmatism, or progressive lenses, bifocals or other multifocal lenses to also correct presbyopia.
EYEGLASS LENS MATERIALS AND THEIR BENEFITS
Glass lenses: In the early days of vision correction, all eyeglass lenses were made of glass. Although they offer exceptional optics, they are heavy and can break easily, potentially causing serious harm to the eye or even loss of an eye. For these reasons, glass lenses are no longer widely used for eyeglasses.
Plastic lenses: In 1947, the Armorlite Lens Company in California introduced the first lightweight plastic eyeglass lenses. They are light weight (about half the weight of glass), low cost and excellent optical qualities, CR-39 plastic remains a popular material for eyeglass lenses even today. Polycarbonate lenses: In the early 1970s, the first polycarbonate lenses for safety glasses were introduced. Later that decade and in the 1980s, polycarbonate lenses became increasing popular and remain so today. Lighter, high impact resistant, blocks 100% UV, making it a preferred material for children’s eyewear, safety glasses and sports eyewear.
A newer lightweight eyeglass lens material with similar impact-resistant properties as polycarbonate is called TRIVEX (PPG Industries), which was introduced for eyewear in 2001. Visually more advantageous than all others and blocks 100% UV and Blue rays.
High-index plastic lenses: In the past 20 years, in response to the demand for thinner, lighter eyeglasses, a number of lens manufacturers have introduced high-index plastic lenses. These lenses are thinner and lighter than CR-39 plastic lenses because they have a higher index of refraction and may also have a lower specific gravity, they block 100% UV rays.
Note: aside the glass lenses, the rest are all plastics.
EYEGLASS LENS TREATMENT
ANTI-SCRATCH COATINGS: can make your eyeglass lenses nearly as scratch-resistant as glass, very durable for Children and Adults alike.
ANTI- REFLECTIVE COATINGS: An anti-reflective (AR) coating makes all eyeglass lenses better. AR coatings eliminate reflections in lenses that reduce contrast and clarity, especially at night. They also make your lenses nearly invisible, so you can make better eye contact and you and others aren’t distracted by reflections in your lenses.
UV-BLOCKING TREATMENT: Cumulative exposure to the sun’s harmful ultraviolet (UV) radiation over a person’s lifetime has been associated with age-related eye problems including cataracts and macular degeneration. For this reason, people should protect their eyes from UV beginning in early childhood. Thankfully, polycarbonate and nearly all high-index plastic lenses have 100 percent UV protection built-in, due to absorptive characteristics of the lens material.
PHOTOCHROMIC TREATMENT: This lens treatment enables eyeglass lenses to darken automatically in response to the sun’s UV and high-energy visible (HEV) light rays, and then quickly return to clear (or nearly clear) when indoors. Photochromic lenses are available in virtually all lens materials and designs.
COST OF SPECTACLE LENSES AND FRAMES
Depending on the type of lenses and lens treatments you choose and the lens design you need, your eyeglass lenses can easily cost more than the frames you choose — even if you choose the latest designer frames. So how much will your glasses cost? That’s hard to say. In the United States, according to Consumer Reports’ latest reader survey published in 2013, respondents spent a median of $150 to $800 out-of-pocket on their last pair of prescription eyeglasses. The amount you pay for your next pair of glasses will depend on many factors, including your visual needs, safety needs and your fashion desires. To get the best value, it’s essential to understand the features and benefits of the products you are considering and to choose wisely with the help of a reputable eye care provider. Look the best, get the pocket-friendly best, give your eye the best.