HOW AR WORKS

Light moves in waves. The construction of the movement consists of crests and troughs. A wavelength is the distance from the top of one crest to the top of the next crest.

AR works on the principle of light wave interference. One type of wave interference is Constructive Interference, where the crests and troughs move together and enhance each other.

Another type of interference is Destructive Interference, where the crests and troughs move opposite each other. When movement of light from the coating is ½ a wavelength out of sync with the movement of light from the lens, the crests of the coating move with the troughs of the lens. The two wavelengths cancel each other out and there is no reflection.

ELEMENTS OF AR COATING

The Hardcoat
A critical component of any anti-reflective treatment is the hardcoat. This is the first layer applied to a lens surface. The hard coat provides bonding of the AR layers to the lens surface. The overall quality of the AR treatment depends in large part on the quality of the hardcoat layer. Higher quality hardcoats are matched to specific lens materials for optimum adhesion, durability and stability.

When the index of refraction of the hardcoat matches that of the lens material, reflections are minimized. If the index of refractions of the lens and the coating don’t match, birefringence occurs. Birefringence is reflection off both the lens surface and the hardcoat, producing a rainbow effect on the front of the lens. If the coating and lens have the same index of refraction, light passes through as though the lens and the hardcoat were one material. This reduces reflections.

THE AR STACK

The AR coating is made up of a stack of alternating layers of high refractive index and low refractive index. The AR layers are responsible for creating the destructive interference patterns needed to knock out lens surface reflections. Each layer interferes with one color range. The more layers there are, the more colors are neutralized. Higher quality ARs have up to seven layers in their stack. The layers provide broad-spectrum anti-reflection and the chemistry of the layers is formulated to be compatible.

THE OLEOPHOBIC LAYER

Premium ARs have an oleophobic treatment as the outside layer of their AR coating. The purpose of this layer is to repel grease and oil, making the lenses easier to clean. This topcoat is also very slick, allowing the cleaning cloth to slide over the lens with less chance of scratching. The oleophobic quality proves its worth with the touch of a finger. The higher the quality of this layer, the less oil is deposited on the lens when it is touched. 

HYDROPHOBIC LAYER

Premium ARs have hydrophobic properties to their topcoat. This treatment causes water to bead up on the lenses so most of it can be shaken off and the lenses can be gently patted dry.

HYDROPHOBIC/OLEOPHOBIC TREATMENT

The hydrophobic/oleophobic treatment seals and protects the AR layers. It acts as an abrasion-resistant coating. It protects the lenses from the assault of cleaning and constant use. This outer layer does not render the lenses scratch-proof, but it is very scratch-resistant.

ANTI-STATIC PROPERTIES

Anti-static properties allow the lenses to dissipate electric charge and prevent charge buildup. It helps keep dust and other airborne particles from clinging to the lenses. Without anti-static properties, static electricity builds up, causing the lenses to attract the dust and particles. Wiping them becomes an exercise in futility — much like wiping a TV screen with a dry cloth. The cloth just chases the dust.

Some Lens manufacturers have developed their own AR that works best on their own lenses. These companies include:

Essilor Crizal Alize with Clear Guard™
This AR is created using an 8-step process that fuses 2-sided scratch resistance with anti-reflective, anti-static, hydrophobic and oleophobic technology.

PANTEX SURPASS^®
Surpass AR begins with a special treatment of the lens surface to maximize AR adhesion. Multiple AR layers, including layers containing titanium for greater coating strength and durability. A layer of EasyClean® Plus seals the AR layers, creating oleophobic and hydrophobic properties.

Opticoate tzAvoRite by Opticote, Inc.
With hydrophobic, oleophobic and anti-static properties, tzAvoRite has a proprietary hardcoat and 7 anti-reflective coating layers that provide superior light transmission and a topcoat that repels water, oil, dust and dirt for extended life and extreme durability. This AR has strict substrate-matching requirements and can be applied only to round, uncut CR-39, polycarbonate, mid-index, 1.60, 1.67, and Trivex lenses.

SOLA TEFLON^®
SOLA’s Teflon EasyCare anti-reflective coating is a proprietary integrated, multi-layer coating. It is a tough hardcoat that delivers scratch and abrasion resistance and serves as an excellent substrate for the anti-reflection stack. The hardcoat is virtually impervious to wear and reduces the possibility of the coating crazing and delaminating.

iCoat Company Vivix Stainless
The primer is chemically matched to the hardcoat, allowing bonding between the hardcoat and the lens material. The primer acts like a cushion and adds impact resistance to the lens. The lenses have an average Bayer rating of 8.0.

Acclaro and ClearVu
Independent labs, some with in-house AR processing, get their machines and formulas from manufacturers, such as Satisloh. The AR formulas are proprietary. Each lab has its own name for their AR, such as Acclaro and ClearVu.

BENEFITS OF AR

• Increased light transmission
  The light that is reflected off non-coated lenses is passed through AR coated lenses, making vision sharper and clearer.

• Reduced eyestrain
  AR eliminates glare from computer screens and reflections from the sides and back of spectacle lenses, resulting in less competition with reflections and more comfortable viewing.

• Better night vision
  Reflections and glare are reduced making night vision sharper, improving night driving.

• Cosmetics
  AR allows the eyes to show bright and clear without the detraction of room reflections.

LENSES THAT BENEFIT FROM AR

• Hi index lenses transmit less light than lenses of lower index because they are highly reflective. AR treatment can increase light transmission to 99%. AR should always be recommended with high index lenses.

• Aspheric lenses are often made in high index materials and they have a flatter profile than non-aspheric lenses. Backside reflections are increased because of the flatter surface. This combination of features makes aspheric lenses excellent candidates for AR treatment.

• Dress eyewear - Because anti-reflective coating increases light transmission, dress eyewear benefits from AR treatment. Vision in all light levels is enhanced, especially in low-level lighting, such as theaters, restaurants, churches. 

• Specialty eyewear, such as for computer work, hobbies or sports, benefit from AR treatment because of the sharp, clear vision it produces.

• Sunwear - The tint on sunwear can make the lenses more reflective. A backside AR eliminates reflections off the back of the lens while the front of the lenses maintains its ray-blocking properties.

PRESENTING AR

• Believe in the product! The best way to help your patients understand how great AR lenses are is to understand it yourself. If you believe it, they will believe it.

• Enthusiastically tell the patient that you know he will enjoy his premium AR lenses.

• Wear AR yourself to see how great the vision is, how easy it is to maintain and how durable it is -- even if you don’t wear an Rx…wear Plano lenses.

• Let the patients hold and “experience” AR lenses, perhaps with a “donut” sample. Let them see close up how AR reacts to touch, dust and cleaning.

• Tell the patient how great you have found the vision to be, how easy it is to maintain and how durable it is.

• Keep up on the latest optical products The trade magazines always have articles and ads about AR. Lens and lab reps are always happy to share their AR products. They will provide point-of-purchase (P.O.P.) materials, brochures and patient literature and demonstration materials.

• A “donut” or “bullet” lens has a circle in the center that has AR treatment with an uncoated ring around the edges of the lens. This donut lens clearly shows the difference between a coated lens and an uncoated lens.

• A frame with one coated plano lens and one uncoated plano lens. When the patient puts on the frame, he sees the difference between the lenses. When the dispenser puts on the frame, the patient can see the difference in the look of the lenses, and can understand the cosmetic benefit of AR coating.

• Demonstrate hydrophobic treatment by laying a treated and an untreated lens face down on a felt pad, tilt the pad and show how the treated lens slides down the pad quicker than the untreated lens does.

• Demonstrate how cleanable a Superhydrophobic/oleophobic lens is by making a mark on a treated and untreated lens with a Sharpie pen. The untreated lens absorbs the ink and has a permanent mark on it. The ink beads up on the AR treated lens and can be wiped off easily.

Offer AR lenses to everyone and provide them with the best vision through the finest, most technologically advanced optical products we can offer.

Dee Carew
ABO/ NCLE, LDO, MLS