Article Date: 9/1/2008

Focusing on Lens Materials and Coatings

Focusing on Lens Materials and Coatings

A marriage between these technologies can enhance vision and elevate the perception of your practice.

By John L. Schachet, O.D., Englewood, Colo.

When it comes to spectacle lenses, materials matter. We have many choices of materials and coatings from which to choose, and these selections make a significant impact on patient outcomes.

In my practice, we track the spectacle lenses that we prescribe, and we find that lenses with elective coatings or premium lenses with built-in coatings have lower rates, remakes and other issues. These compelling results have prompted us to use the very best products for all of our patients whenever possible.

Since we've made an effort to focus on premium lenses and coatings, our patients are more satisfied, and we've seen a significant difference in our bottom line. Our patients' perspectives on eyeglasses also have changed in the process. Now patients come in for their annual exams and ask, "Do you have anything new?"

As new O.D.s, all of you can achieve these outcomes by choosing and pairing the right lenses and coatings, and then planning how best to integrate these materials into your practices. Read on to learn how.

Selecting Lens Materials

Lens materials and coatings often are inseparable. Most lenses have built-in ultraviolet (UV) coatings, and most premium lenses come with additional coatings. When coatings aren't integrated, the properties of the material will influence your choice of lens coatings.

Typically, you'd choose the following spectacle lens materials based on a patient's prescription and lifestyle, and on the desired lens thickness, weight and price.

Plastic: Plastic lenses are versatile and can be used in most spectacles, including lenses that darken and sunglasses. Optically, they're not the clearest choice available.

Polycarbonate: Polycarbonate lenses are lighter, thinner, and more impact- and scratch-resistant than plastic lenses, so they're a good choice for children and when safety is an issue. They lighten high prescriptions and have built-in UV protection. They're also very versatile for tinting, darkening or polarization. However, polycarbonate lenses still have some visual distortion, and their ABBE value isn't top-notch.

Trivex: Trivex lenses are lighter than polycarbonate, have less distortion and offer excellent impact resistance. UV protection is built in. This material is more expensive than polycarbonate and is a good choice for children, as well as for general outdoor wear and rimless frames. Additionally, the ABBE value is higher than that of polycarbonate lenses.

Hi-index: Hi-index lenses are the thinnest and most expensive choice, but they're not as lightweight and impact-resistant as Trivex. These lenses are good for high prescriptions, and they have built-in UV protection.

You can pair all of these lens materials with a variety of lens coatings that are appropriate.

Choosing Coatings

Lens coatings can reduce glare, scratches, static electricity, fog and UV penetration. (See "Understanding Spectacle Lens Coatings.") Depending on a patient's prescription and lifestyle, we might select premium lenses with built-in coatings or choose to apply optional coatings to their lenses. The number of coatings ranges from one to 12 (six on the front and six on the back). In the past, anti-reflective coatings used to scratch or smear easily. Peeling occurred, and we'd have to replace the coating or remake the lenses. Today, we don't have these problems.

We recommend an anti-reflective coating for every adult. The coatings reduce glare, and without glare, patients see more clearly in everything they do. It's a significant difference that many patients notice when driving in the daytime and at night. Older adults who have cataracts or issues in the media need as much light as possible, and an anti-reflective coating allows more light to go through the lens. (See "Influencing the ABBE Value.") Computer users also appreciate the relief from glare.

If a lens material isn't scratch resistant, it's important to add a scratch-resistant coating. However, for patients with polycarbonate or Trivex lenses, which are relatively resistant to scratching and breakage, we may not recommend an additional anti-scratch coating.

Other lens coating choices are dependent on the patient's occupation and lifestyle. An anti-static electricity coating keeps eyeglasses cleaner, especially in dry or dusty environments. A fog protection coating is useful in moist environments, because it helps prevent "fogging up" during activities, such as exercise and cooking.

Regardless of the coatings we choose in our practice, the motivation is always the benefit to the patient. We frame the discussion around that benefit.

Streamlining the Options

I'm a founding member of a busy primary care practice that's been around for nearly 35 years. We have five doctors working full time and part time. We perform a great deal of medical eye care, serving patients with dry eye, red eye, allergies and glaucoma. And we perform regular exams, vision correction and contact lens fitting. My colleagues and I want to give patients the lenses and lens coatings that will enhance their vision and support their lifestyles, and we want to do so in a way that complements our work process.

Only a streamlined approach will work for us. To that end, we select the best lenses that incorporate beneficial coatings, and we sell lenses with certain coatings as a package to make it easier for patients to buy.

In the past, we had to discuss and sell optional coatings, even for top-of-the-line lenses. But most premium lenses today, especially those for presbyopia, incorporate coatings as a package from the manufacturer. This simplifies our process enormously. You can't order the lens without the coatings, and they're built into the cost.

If a patient is changing from an uncoated to a premium lens, it's worth mentioning the type of coatings on the premium lens. They'll notice that their vision is clearer. In my practice, patients with new multifocals experience a wow factor that I'd never seen before the manufacturer-incorporated coatings became available.

Packaged coatings serve several purposes. First, it eliminates a lengthy a la carte list of coatings for patients to consider. That means a reduced shopping burden for them and a lighter selling burden for you. Instead of asking them to pick and choose among $50, $75 and $100 coatings, we offer one or two packages of the coatings we think they need the most. For example, we might bundle anti-reflective, anti-scratch and anti-UV coatings for plastic lenses.The packages are value priced, making them more affordable. Affordability isn't just good for patients' wallets, but it's also good for you, because a fair price means you're more likely to succeed in offering patients the coatings that will increase their success and satisfaction.

Seeing and Explaining the Difference

Depending on the practice, discussion of lens materials and coatings might take place with the doctors or the technicians. In my practice, we do both: we prescribe premium lenses, and we explain this to patients while we're writing the prescription. The optician continues the discussion, but it begins with us. I explain to patients, "I want you to be in this new lens because it's a premium lens. Here's how it's different …" The optician will explain more, but I want patients to understand the prescription and understand that I'm recommending a certain lens for them because I believe it's best for them.

If a patient tells me that he can get cheaper eyeglasses down the street, I flip over the prescription sheet and write down the lenses that are fair, better and best for his vision. I explain, "I only prescribe what's best. You're welcome to go wherever you like, but be sure to take this paper along and compare apples to apples. Cheaper eyeglasses are probably lower quality eyeglasses. We offer the fair or better choices here, but the best quality is what you come to us for and that's what we recommend for you." For example, we're in the fifth-generation of progressive lenses, but another practice might offer him third-generation progressives. Patients almost always choose to stick with us.

All of our decisions for lens materials and coatings are based on the benefit to the patient. That's how we discuss the options with them, and that's why they trust us. It's a very powerful combination that ensures we almost always get patients into the lenses we think are best. nOD

Understanding Spectacle Lens Coatings
Several types of coatings, used individually or in combination, can help enhance your patients' vision and quality of life. Here's a sample of what's available:
Anti-reflective/anti-glare: Anti-reflective coatings reduce glare while increasing the amount of light that can pass through the lens. This improves vision for any spectacles wearer, and it's especially popular with older patients and computer users. Premium anti-reflective coatings, such as Crizal Alizé (Essilor) and Super Hi-Vision (Hoya), are harder and last longer than standard coatings.
Anti-scratch: This coating prolongs the quality, appearance and life of eyeglasses. It's a must for plastic lenses, and it's typically built into premium lenses.
Anti-static electricity: Static electricity makes dust and dirt particles stick to lenses, especially in dry environments. This coating keeps debris from sticking to lenses and makes them easier to clean.
Anti-fog: This coating is often used on safety eyeglasses, but it's also useful for people in moist environments and those whose eyeglasses fog up while exercising or cooking.
UV-block: Built into most lens materials, this coating protects eyes from harmful ultraviolet (UV) rays.

Influencing the ABBE Value
The ABBE value, also called constringence or the V-number, is a measure of dispersion of light through a lens. Lenses with a high ABBE value allow little dispersion and are clear, whereas lenses with a low ABBE value allow more dispersion and are less clear. A low ABBE value can mean that the lens wearer will see color fringing (chromatic aberration).
A significant difference in ABBE values exist among common lens materials. Polycarbonate lenses have an ABBE value of about 30, compared to 43 for Trivex. By adding an anti-reflective coating to either of these materials, we can reduce dispersion and raise the ABBE value, so patients will see more clearly.

John L. Schachet, O.D., is in private practice in Englewood, Colo.

Optometric Management, Issue: September 2008