Focus Eyecare Wilmington NC | Lens Technology
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Focus

Lens Technology

The top priority of any eyewear is to give you the clearest vision possible. Lens technology has been revolutionized over the past decade. Not only do these incredible advances allow you better vision with less distortions, it incorporates thinner, lighter materials for a cleaner look and more comfortable wear.

A truly successful fit means that your eyeglasses meet the visual demands of your world. Before we can choose a lens material or treatments, we’ll need to know you! It is essential to consider all the elements of your visual world: is it close up, far away, how many hours do you spend on the computer, and do you have to see distance simultaneously, are you outside much of the day or under fluorescent lights? We also need to consider the size, shape, and thickness of the frame you’ve chosen to be sure the lens will be a good fit visually—in both senses of the word.

Many opticals buy from only one lab, but at Focus Eye Care, we have relationships with numerous labs. This gives us freedom to make an unbiased choice from multiple lens materials and optical designs in order to best match your needs. When we suggest a lens design, material, or treatment, be assured it is not chosen because it carries the highest profit margin. If that was our motivation, we would sell the same lens to everyone! It’s the lens of choice because it’s the right for you and your needs.

Together, we will consider how the materials and treatments will influence your vision, comfort, appearance, and safety. We know this can be a daunting task, but we are here to help! We are here to inspire! And we are here to help you aspire!

LENS MATERIALS

Glass lenses

The original lens material. Despite the remarkable optics and scratch resistance, glass is heavy and risks shattering, so it is rarely used today.

Plastic lenses

In 1947, after 38 unsuccessful attempts, CR-39 was introduced as the first successful plastic eyeglass material. It’s approximately 50% lighter than glass, has excellent optics, and can be coated to improve scratch resistance, filter UV light, or add color. CR-39 is still widely used today, though there have been many improvements since the 40’s.

Polycarbonate lenses

In the 1970’s, polycarbonate was introduced as the lightest material available. It is the most impact resistant, strongest, and safest material, and can be coated to improve scratch resistance. It blocks 100% of ultraviolet light, and is up to 25% thinner and 35% lighter than plastic. Because of its unsurpassed protection, this is the standard of care, and often mandatory, for children’s eyewear, and certainly for safety lenses.

Trivex was introduced in 2001 and is very similar in safety profile compared to polycarbonate. It is currently the lightest material on the market. It blocks 100% UV light and creates fewer aberrations (colored halos) verses standard polycarbonate, which can equate to better visual clarity.

High-index plastic lenses

Hi-Index lenses are generally broken into two categories: 1.60 to 1.67 and 1.70 to 1.74. The 1.74 high-index lens is the thinnest lens material available, dramatically improving the aesthetics of any lens, but especially those with high prescriptions. They block 100%UV light and are coated for scratch resistance. Numbers are just numbers, without context and we don’t want to leave you hanging—so CR-39 has an index of 1.498 and polycarbonate is 1.586.

LENS DESIGNS

What are near-sightedness, far-sightedness and presbyopia?

Please see the Optical Terms page, which explains all of these in detail.

Visualize It

Free-form lenses

Wavefront guided design.

Aspheric lens design

CR-39 and polycarbonate materials can be fabricated in an aspheric design. This means the lens curvature changes more gradually, so a flatter lens can be used. Aesthetically, the lens will have a slimmer profile and you will notice less unwanted eye magnification with high plus prescriptions (or miniaturization with high minus prescriptions). It may also improve peripheral vision for some.

Single vision

With single vision, the entire lens has the same power. If you are under 40 years old, this is probably all you need to see both far and near. However, if you are over 40, you will likely have to choose between seeing clearly at distance verses near with your single vision lenses. Obviously, it would be crazy to continually switch back and forth for every task. But if you want to spend concentrated hours at one task, single vision lenses will give you the most comfortable vision for a particular distance.

Bifocals

Bifocals contain two powers. The top of the lens allows you to focus in the distance, the lower portion allows you to focus at near.

Trifocals

Trifocals contain three lenses: one for distance, one for near, and an addition midrange zone that allows you to focus on your computer. Because there are three zones, each zone is smaller, and the line is placed higher on the lens. The advantage over traditional bifocals is that you don’t have to continually move in and out to find the perfect focal point at near.

No line progressives

Progressive lenses gradually increase in power from the middle of the lens to the bottom, thus containing many powers. They are often referred to as “no lines” since there is no visible line. Though these lenses may take longer to adjust to, they typically provide the most comfortable vision and the most generous range of viewing distances. Just like dessert, some things are worth the wait!

LENS TREATMENTS

Scratch resistant coating

All plastic lens materials are significantly softer and more easily scratched than glass, if not coated with a hard, scratch-resistant layer. The coating is made of a much harder plastic compound to provide an added level of scratch protection that rivals glass. But it too can eventually become scratched over time. Once scratched, a lens cannot be repaired or “buffed” to remove the scratch. No scratch coating alone can be guaranteed not to scratch; it is simply added protection from scratches. However, if you are extra hard on your glasses, or you are buying for your kids, consider investing in a replacement program.

Anti-reflective (AR) Coating

An AR coating consists of multiple microscopic layers applied in a vacuum, on either the front surface or both surfaces of the lens, to virtually eliminate light reflections. This helps to improve visual contrast and clarity. AR coating is very helpful to reduce glare during night driving and computer work. An AR coating also makes it easier for other people to see your eyes behind the lenses. Reducing reflection is especially important if you’ve chosen a high index lens because without it, they can reflect up to 50% more light than a CR-39 lens, causing significantly more glare.

Now, when thinking of AR coatings, you must compare apples to apples…and there are some rotten ones out there! Point being, not all ARs are created the same. If you opt for a cheap AR coating (one thing you can’t get here), it can become scratched and damaged very easily. This will cause your vision through the lenses to be worse than if you had opted out on the AR all together. So go all in or leave it off!

Because there are fewer reflections, sometimes fingerprints seem more visible on the lens. High grade AR coatings are easier to clean than the others. Be sure to use an official cleaning cloth and cleaning fluid approved for AR coatings.

Ultraviolet blocking protection

The sun radiates ultraviolet waves, which are extremely damaging to the human eye and skin. Over time, its accumulation can lead to cataracts and even macular degeneration. That’s why it’s important to protect your eyes, starting in childhood. Lenses with ultraviolet protection help prevent harmful UV radiation from reaching your eyes. Polycarbonate, high-index, sun-sensitive photochromic, and polarized lenses all have built-in UV protection. Only CR-39 plastic lenses need an additional coating for UV protection.
Be careful out there: http://www.allaboutvision.com/sunglasses/spf.htm

Photochromatic treatment

Photochromatic treatment allows your lenses to darken in response to UV light, and then automatically return to clear when indoors. This technology has seen dramatic improvements over the past several years, related to how dark they get and how clear they get. However, keep in mind that when you are driving, the windshield blocks out much of the UV light, thereby reducing the stimulus for the lenses to darken. There are photochromatic treatments specifically designed to turn dark in the car, however this version will not turn completely clear indoors. Photochromatic treatments are now available in virtually all lens materials and designs, and in multiple colors.

Consider this: http://www.allaboutvision.com/lenses/photochromic.htm

SUNGLASSES

We carry a large assortment of designer sunglasses for fashion, sport, and driving. But keep in mind that, with or without a prescription, we can add polarized lenses, in the color of your choice, to any ophthalmic frame on the shelf, thus creating custom sunglasses you won’t see elsewhere on the beach.

Mirror Finish

A mirror finish consists of thin layers of various metallic coatings on an ordinary lens. Although they do reduce the amount of visible light entering your eyes, you will need a UV coating to fully protect against UV radiation.

Every sunglass has color

Ultimately the choice is one of personal preference, but there is something to it…

Gray is best for 100% accurate color discrimination.

Green mildly heightens contrast while preserving color perception.

Brown or copper greatly enhances contrast (especially against water, snow, sky) and visual acuity.

Yellow enhances contrast and visual clarity in low light and overcast conditions (also amber, red, and orange).

Color guide: http://www.allaboutvision.com/sportsvision/lens-tints-chart.htm

Polarized sun

Have you ever noticed that sometimes you still squint from the brightness, even though you’re wearing your sunglasses? Polarized sunglasses are phenomenal at reducing glare from light reflected off of flat surfaces, such as water or snow. This means that when wearing polarized lenses your eyes and brow are relaxed and comfortable behind them, but it also enhances your visual clarity. Polarized lenses are an essential purchase for any fisherman, aiding in his ability to see the fish below the surface.

Don’t get mad: http://www.allaboutvision.com/sunglasses/

How much should you expect to spend on your glasses?

That’s hard to say! No single combination of lens material, design, or treatments fit every patient. And in many cases, having only one pair of eyeglasses, even if it’s custom designed for you, may not suit all of your visual needs at once. It depends on your visual and occupational demands, your fashion desires, and your vision insurance. Keep in mind that if you choose high-end designer frames and aspheric, high-index progressive lenses with premium anti-reflective coating, it’s not unusual for the cost of your eyeglasses to exceed $800. On the other hand, if you’re buying your child’s first pair of prescription eyeglasses with polycarbonate lenses for mild myopia, the cost will be much closer to $200 for quality eyewear, and a scratch-resistant warranty.

Most importantly, take your time to fully understand the features and benefits of the lens materials, designs and treatments. Too often, patients regret opting out on a feature because it cant’ be added later and they have to start over. Our primary concern is that your experience in our optical is a joyful and inspiring one and that you are absolutely thrilled with your purchase, long after you leave the building! We commit to offer you unbiased advice with only your interest at heart.