Optical Lenses and Coating Glossary
Anti-Reflective Coating: This is a coating which can be applied to the outside or inside surface of any lens (clear or sun lens) to minimize the amount of light reflected by your lenses. It reduces reflections and glare. Reflections and glare may cause headaches or interfere with vision clarity. Regular lenses reflect a very small amount of light back into your eye, possibly skewing vision; anti-reflective coating helps to prevent this. It is best used on the back surface of a sun lens to minimize back glare.
Anti-Scratch Coating: A Coating applied to the outside of the lens to minimize scratching. Does not make the lens scratch proof, but helps in reducing fine hair line scratches. All polycarbonate lenses come with an anti-scratch coating.
ANSI Standard Z87.1: The new standard is now called the ANSI Z87.1-2003 standard, and is performance driven with two levels of performance for non-plano (prescription) lenses.- Basic Impact- High Impact
• The new standard requires that prescription safety frames must meet the lens retention (High Velocity and High Mass) test requirement with 2.0mm lenses.
Please be aware that an employee subjected to High Impact may not be adequately protected if wearing lenses tested only for Basic Impact. Description of the new ANSI testing requirements:
High Impact Level Prescription Lenses
• Must not be less than 2.0mm thick.
• The lenses shall be capable of resisting impact from a 6.35mm (1/4 in.) steel ball traveling at 45.7 m/s (150 ft/s).
• Marking by manufacturer with “W” as a trademark would look
like this: W+ Basic Impact Level Prescription Lenses.
• Basic Impact lenses shall be a minimum 3.0mm thick except those lenses having a plus power of 3.00D or greater shall have a minimum thickness of 2.5mm (no change from the 1989 standard).
• Basic Impact lenses are not tested to stringent High Impact requirements.
• They will NOT be marked with a “+”
• Protectors with Basic Impact lenses will be delivered to the wearer bearing a Warning Label indicating that the protector only meets the Basic Impact Standard
Backside anti-reflective (AR) coating: light that comes from behind can cause you additional glare. Sunlight will hit the back of the lenses and bounces into the eyes. The purpose of a backside (AR) coating is to reduce the reflection off the lenses.
Ballistic Ballistic is any projectile in a high velocity.
Bifocal Lenses- Provides 2 types of Vision correction- One for distance and for near.
Blue Blocker Is a type of lens that will block the visible blue light without darkening the overall light. These lenses are usually brown, orange or red.
Color-Coated Lenses: Coloring on the outside of the lens. Lens mirror coating is a process that usually involves a metallic oxide coating being applied to a lens in a vacuum deposition to get the coatings evenly deposited across the surface. There is only a hand full of these machines in the United Stated that are used in these processes because of their expense. Every time a color is applied to a batch of lenses, the vacuum chamber must be meticulously cleaned to keep the next batch of a different color from being affected by the previous operation. Most coating labs run certain colors just once a week to keep the labor and materials expense down. Adversely mass produced lenses that you would get in a stock pair of sunglasses is done in a assembly line fashion, running a huge batch of lense all the same color until the run is complete. Custom prescription lenses are not cycled this quickly and usually takes a week for the turnaround time.
CR-39 (plastic) The advantages of plastic is that it is lightweight and easily tinted to just about any color. One of the disadvantages is that those lenses scratch easily.
Custom Lenses- Custom lenses are cataract lenses that allow patients with very bad vision get most of their sight back along with slab off lenses that help patients with vertical imbalance see much clearer without double vision effect. This type of correction is called a slab-off or bicentric grind.
DriveWear transitional lenses are the first and only photochromic lenses to darken behind the windshield of a vehicle, with the ability to react to visible light as well as UV light. By combining polarization with new photochromic technology, DriveWear lenses are capable of sensing and reacting to varying light conditions both outside and behind the windshield of the car. From bright sunlight accompanied by intense, blinding glare, to overcast inclement conditions,
G-15: Green-Gray lenses are the most popular general purpose lenses. Uniform absorption of colors throughout the spectrum allows colors to be seen exactly as they are with approximately 85% light absorption.Glass lenses: One major advantage is that it is very scratch resistant. However it is double the weight of conventional plastic. Also it is not as shatter resistant or safe as plastic. Can easily be tinted.
Glass lenses are the most scratch-resistant and distortion-free, but they are also heavier, more expensive and more likely to shatter.
High index 1.56: Thinner and lighter than regular plastic good for higher prescriptions. Can easily tinted into sunglasses.
High index 1.60: Thinner and lighter than 1.56 high index. These lenses already come with a scratch coat. Great choice for higher prescriptions.
High index 1.67: Thinner and lighter than 1.60. These lenses already come with scratch coating. Also a great choice for high prescriptions.
Impact Resistant: Resistant to shattering or splintering. impact resistant plastic is made so that it will not break into small pieces. Polycarbonate is impact resistant making it a very safe lens to wear.
Infrared (IR) Radiation (760 – 3000nm) Infrared Rays are radiant energy, or heat waves, not considered harmful under normal conditions. These heat rays cannot be seen but can be felt. If you are exposed to intense sunlight for a lengthy period of time (a day at the beach, for example) without infrared protection, you may experience a burning or stinging sensation in your eyes and a sense of fatigue. Infrared rays can be especially discomforting if you wear contact lenses. If your sunglasses fail to stop infrared light, it can be absorbed by your contacts, causing them to “warm up”
Melanin Polarized lenses: “The three main concerns eyecare professionals have with sunlight are UV radiation, Blue light, and Glare. This trio of challenges is often not addressed by most sun lenses, and those that do address them don’t necessarily address them well. Polarized Melanin Lens gives ultimate protection against all three. Ultra-violet light is the high-energy, invisible light ranging from approximately 190nm to 380nm. The UVA portion (315nm to 380nm) is considered harmful to the eye-causing problems such as sunshine or brown cataracts, increased pterygium, and photokeratitis. Sources of UV include direct exposure from the sun and computer monitor as well as reflective surfaces such as water, sand, and snow. Blue light, or more accurately the blue and violet portion of the visible light spectrum, is the high-energy visible light (HEV), which research is beginning to indicate is a contributing factor to age-related macular degeneration (AMD). Visible glare is caused by sunlight reflected off surfaces such as water, roads, car windshields, snow, and sand. Polarized Melanin Lenses will be well suited to your active outdoor patients who are looking for a comfortable sun lens that is impact-protective and absorbs harmful light radiations. Consider it for boaters, hunters, skiers, hikers, forest rangers, police officers, or anyone who spends a good deal of time out-doors.” *
Mirrored Coating: Also called Flash Coating, it is applied to the outside of the lens and can be applied over any base color. New laboratory processes have created coatings that adhere better to the surface of the lens, are less susceptible to scratching, and are available in an expanded palate of colors. Mirror coated lenses absorb anywhere from 10 percent to 60 percent more light than uncoated lenses, depending on the type and degree of coating. The light transmission is further reduced by the base tint of the lens. Due to its reflective property, any mirrored lens will appear darker since it will reflect a certain amount of light trying to reach the eye. A mirrored lens will also add an extra buffer against glare. This makes them ideal for outdoor uses such as skiing. Care and Cleaning: Because most mirror coatings are applied to the surface of the lens, extra care must be taken when cleaning a mirrored lens to prevent scratching and other damage to the surface. Lens cleaning cloths should be used rather than abrasive cotton or paper towels. Dawn dishwashing soap is a good cleaner, but don’t use other household cleaners such as Windex.
Photochromic: Able to change lens color or darkness/density depending upon the degree of exposure to light.
Polarized Lenses block out virtually all Ultra Violet Rays. These lenses help to eliminate haze and glare, while increasing visibility. Colors appear more vibrant while others are subdivided to give the wearer true view without the irritating sun. Excellent for driving!
Progressive lenses -Also Known as No-Line Bifocals. The progressive multifocals have a distance viewing area in the upper area of the lens, down to where the near correction begins.
Reading Glasses have lenses with stronger powers because they incorporate both the distance and near powers to concentrate power for easy reading for the wearer.
Sun Lenses are lenses that have a dark tint or a coating. These lenses help reduce light transmission and come in many colors such as yellow, blue, mirror etc.
Super Mirrored Coating: Mirror coatings on eyeglass lenses serve the dual purposes of fashion and function. The best selling colors of silver, gold and blue have different properties and manage different needs, and other colors serve niche needs. These fashionable and functional coatings however, have had limited appeal because of four major drawbacks:
· Mirrored lenses scratch easily
· Repeated cleaning of mirrors will eventually wear the coating off the lenses
· Mirrors are difficult to keep clean
· Backside reflections cause visual discomfort
Poker Mirror: The Poker Mirror is a hard mirror coat over a slight tint, designed to be worn indoors. The purpose is to obscure the eye while still allowing enough light to pass through the lens to see while playing poker, or engaging in similar activities. The anti-reflective coating on the back helps reduce distracting reflections from the back surface of the lens.
Polished edges= Instead of leaving the edge of the lens with the matte finish from the edger, it can be polished. This is only recommended for clear glasses. With a polished lens on sunglasses you can get chromatic aberrations within the lens from the light coming into the edge of the lens. Also lenses with polished edges are difficult to keep in a wrapped frames for sunglasses.
Polycarbonate- Polycarbonate lenses or “Poly” are “impact resistant” thinner and lighter in weight than traditional plastic eyeglass lenses, they also offer ultraviolet (UV) protection and scratch resistance. In addition, they are very impact resistant. This extra toughness makes them the lenses of choice for children’s glasses, sports eyewear and safety glasses.
TD-2 Coating: While the regular polycarbonate, and top-mount polycarbonate lenses have a factory-applied scratch-resistant coating, it is not as hard as the TD-2 coating. The TD-2 coating does add about 2-3 days to the turn around time on your prescription order. One thing to note, is a TD-2 coated lens cannot be tinted.
Transitions-The leader in plastic photochromic lenses to the industry. Transitions continue to develop the technology for changing lenses.
Trifocal – Lenses in which which there are 3 areas to correct vision. Distance, intermediate and near.
Trivex: offers strength and impact-resistance, light weight and thinness, and quality optics. TRIVEX lens material lets you prescribe a single lens with the qualities of many. This revolutionary lens material combines the key lens attributes your patients are looking for while offering the superior optics you demand. Only the finest lenses provide tri-performance. TRIVEX is the world’s first tri-performance lens material; meaning it offers a triple combination of features never before found in a single material. Superior Optics. Impact Resistance. Ultra light Weight. This breakthrough in technology is specifically designed to deliver the most comprehensive performance of any lens material, anywhere.
Ultraviolet (UV) Radiation: Solar radiation is formed by visible and invisible light waves. Measured in nanometers, it has three wave lengths that reach and affect your eyes: Ultraviolet, Visible Lights, and Infrared Radiation. The shorter the wavelength, the more damage to your eyes.Studies show that long term exposure to UV rays may cause eye diseases, including cataracts. In addition, short-term exposure can cause temporary conditions such as “snow blindness”, Ultraviolet radiation can be divided into three categories.
UVC (200 – 290 nm)-UVC is absorbed by the atmospheric ozone layer and never reaches your eyes.
UVB (290 – 320 nm)-UVB is a physically painful form of ultraviolet radiation. These are the sun’s “tanning rays” which are absorbed by the cornea. Exposure to UVB can temporarily damage the cornea. This band of radiation causes cancer and burning of the eye and has been linked to damage of the lens inside the eye.
UVA (320 – 380 nm)- UVA rays are absorbed by the lens of your eye. The resulting damage heals slowly, if at all. About one percent of all UVA rays penetrate the retina, which cannot repair itself. These rays, which cause sun tanning and wrinkles, pass through the outer structure of the eye and are absorbed by your eye’s lens. The resulting damage heals slowly, it at all. Extended exposure to UVA rays can lead to the formation of cataracts.
Protection from harmful UV radiation is becoming more and more important as the earth’s ozone layer continues to be depleted. Clouds, Smog, Haze do not block out UV rays. You can get higher exposure to UV radiation on snow, sand, water, or concrete, and high altitudes. Excessive exposure to UV radiation today can cause eye problems tomorrow.
UV Filter (coating) This coating is a filter for the harmful UV radiation. The coating is either put on the lens or is imbedded into the lens to protect your eyes for the harmful effect of the sun’s UV radiation.
Resources
Similar Posts:
- Optical Glossary
- Eye Need To Know- Where Did CR-39 Come From?
- eye Need To Know- What Is The Rarest Eye Color?
- Eye Need To Know- What Is Eye Tracking?
- Managed Care Terminology
Recent Comments