Years ago, the only decision you made when purchasing glasses was the style of the frame. Those days are over. Now consumers not only select from a bevy of frame styles, but they also have an array of options when it comes to lens materials and coatings.

“We started out with a single option, which was glass lenses,” says Gregory W. Good, O.D., Ph.D., professor of clinical optometry and assistant dean for clinical services at Ohio State University. “Now glass lenses are almost obsolete and we’re able to offer lighter, tougher materials that are still scratch resistant.”

According to VisionWatch, the Vision Council’s large-scale consumer survey, an estimated 150 million Americans wear glasses. And many are largely unaware of the implications of their lens buying decisions. Here’s a breakdown of lens materials and lens coatings so you can select the best spectacles for your unique needs.

Lens Materials

• Glass: Glass lenses are much less popular these days, but they’re still available. “They’re our best lens in terms of optical properties of the material,” says Good, “but they’re the weakest lens we make.” In fact, many optometrists avoid glass lenses because of safety concerns if the lens should break.
• Plastic (CR39): Plastic lenses are lighter and more durable than glass lenses. The most common plastic material is called CR39. If you have a low prescription (e.g., mildly near or far sighted), CR39 offers a high quality lens for less money. “It’s thicker than other lenses, which is why we typically recommend it only for lower prescriptions,” says Good.
• Polycarbonate: When your prescription gets a little higher, your vision care provider will almost always recommend polycarbonate lenses. They’re tougher and more impact resistant than CR39 and they have a higher index (ideal for higher prescriptions). They’re also thinner and lighter than conventional plastic or glass. The only downside: Polycarbonate lenses have peripheral distortion, meaning you may see a spectrum of color when you look off to the side.
• High index/aspheric: High index and aspheric lenses are very expensive, but they’re also lighter and thinner than glass or plastic lenses. And they’re great for people who have a strong prescription that would ordinarily require very thick glasses. “As you become more near sighted or far sighted, you might need a high index lens so you don’t have as many optical distortions on the periphery,” says Good. The higher refraction of these lenses allows the material to bend light to a greater degree so less curvature is needed in the lens to achieve a higher prescription. High index materials are available in plastic, polycarbonate and glass.

Lens Coatings

• Scratch-resistant: Scratch-resistant coatings make lenses tougher. Today, most glasses come standard with scratch-resistant coating, but they’re also incorporated into other coatings like anti-reflective.
• Anti-reflective: This coating helps reduce glare. So, for example, when you’re driving at night, you won’t see lights reflecting off the lens and into your eye. These coatings also get rid of the reflection off the front of the lens, enhancing your vision and your appearance (because people can see your eyes!). In professions like teaching where eye contact is key, anti-reflective lenses are important, claims Good.
• UV coating: These days most lens materials offer some UV protection. “CR39 let a little UV radiation through, but the other materials like polycarbonate and high index materials do a good job at blocking out UV radiation,” says Good.
• Mirror coating: Want to keep your students on their toes? These lenses allow you to scan the playground without anyone seeing your eyes. Instead of absorbing light the way most sunglasses do, mirror coated lenses reduce the amount of light by partial reflection so the light that is not transmitted is reflected. “It’s like a two-way mirror,” says Good.
• Transition lenses: People who are sensitive to light might benefit from transition lenses because they automatically darken when exposed to light. “You don’t have to worry about where you left your sunglasses because the coating darkens when you go outside,” says Good.
• Polarized lenses: These lenses are the perfect choice for people who do a lot of sailing or fishing. “Polarized lenses reduce reflections,” says Good. “So if you’re looking down into the water, they can break through any reflections you see on the surface.” Another option: get a polarized clip as an add-on to your regular lenses.

Bottom line

Buying glasses is no simple task. The options are seemingly endless and they’re often directly related to your personal prescription. Do you have a heavy prescription and wear glasses 24/7? If so, high index, anti-reflection, transition lenses may be your best bet. Do you wear contact lenses during your waking hours and rely on glasses only early in the morning or late at night? You might be able to get away with polycarbonate frames or even inexpensive plastic CR39 with scratch-resistant coating. No matter what your level of eye impairment, when it comes time to buy glasses, don’t go it alone. Work closely with your eye care professional to select the best glasses for your unique needs and take a friend or co-worker with you to select the best frames for your face.

Please note: Any medical information provided on NEAMB.com, such as text, graphics, images and other material is for informational purposes only. More information.