Glossary of Sunglass Terms

Acrylic
A lightweight plastic material used to make sunglass frames.

All-Weather Photochromic
Lenses that work well under all-weather conditions, including overcast and hazy days. On overcast days, they are light amber and improve contrast and sharpen details. In sunshine, they turn dark brown. At all stages, they improve contrast. They are excellent for any outdoor activity.

Anti-Reflective Coating
A violet-colored coating on the back of a lens that prevents sunlight from coming in from behind and reflecting off the back of the lens into the eyes.

Brown Lens
Excellent for general-purpose sunglasses. They improve contrast by filtering out blue light and reducing glare. They are the ideal lens color for sports with high glare such as skiing, boating, and fishing and are well suited for driving and fast-reaction sports.

Constant Density
Lenses whose tint is uniform throughout the lens. The majority of sunglass lenses on the market are constant density. They are fixed in the percentage of light they absorb.

Corrosion Resistant
The ability of a metal part to maintain the integrity of its surface finish without significant deterioration when exposed to perspiration, salt sprays, acids, etc.

Cosmetic Lens
Unusual transparent color lenses, such as pink, sky blue, and purple, become trends from time to time. These are often worn indoors as a fashion statement.

CR-39
Considered the best plastic for lenses, it has the highest optical rating among plastic lenses. It offers the best scratch resistance compared with other plastic lenses.

Double-Gradient Mirror Coating
A lens that is mirrored on the top and bottom, but not in the middle. The mirror on top reflects sun from above, and the mirror on the bottom reflects glare from below.

Full-Mirrored
A mirror placed completely over the complete lens. It provides the most protection against glare.

General-Purpose Lens
Basic, all-around lenses, good for everyday use and a variety of activities. The most common colors for general-purpose lenses are green and grey.

Gimbaled Nose Pads
The nose pads are attached to the eyeglass frame in such a way that the pads can pivot and turn in right angles to the frame.

Glare
Glare is too much light for the eyes to handle comfortably and efficiently. Glare can come directly from a light-source or it may be reflected. Most often, glare is a combination of bright overall direct light and reflections.

Glass
Optical quality glass is the clearest lens because it's free of anything that could distort vision.

GPL
Glass Polarized Lenses

Gradient
Lenses that are darker at the top and get progressively lighter at the bottom. Lightly tinted versions of gradient lenses are used mainly in fashion glasses.

Graphite
A combination of carbon and fiberglass materials producing frames that are extremely lightweight and strong.

Green Lens
Good all-around general-purpose green lenses provide contrast in low light conditions and reduce eyestrain in bright conditions. Filters some blue light as they protect against glare. Green lenses only allow the most useful light to reach the eye for greatest visual acuity. They are the most preferred of all lens colors.

Grey Lens
Grey is a neutral shade and a good general-purpose color. Colors pass through gray lenses evenly, allowing true perception and the least amount of color distortion of any lens color because it does not enhance contrast, an important feature for sports such as golf, cycling, and running. Grey lenses protect well against glare, making them excellent for sports, outdoor work, and driving, as well as general wear.

GSM
Gradient Silver Mirror

Hardcoating
Scratch-resistant coatings put a hard layer on the surface of plastic lenses that resist, but do not prevent, scratching. This type of treatment is most common on plastic lenses, but is also used on glass.

HEV Radiation
A growing body of research has linked HEV radiation - visible light just beyond ultraviolet (UV) radiation on the wavelength spectrum - to macular degeneration, a disease of the retina that affects 13 million people in the United States. There is no known cure, and the condition is the leading cause of legal blindness in people older than 50 in the Western world.

Impact-Resistant
The ability of a lens to withstand impact without cracking, breaking, fracturing or chipping.

Infrared Light
Infrared rays are long wavelength rays, sometimes called "heat waves." They cause the skin to feel hot, but it is the short wavelength UV radiation that causes sunburn.

Iridium
A mirrored lens coating.

Light Spectrum
The distribution of energy given off by a light source such as the sun, arranged in order of wavelengths.

Metal Frame
Metal frames usually start with base metals that are copper or nickel alloys. They are then plated with fine metals, such as gold, to give them a rich finish.

Mirrored Coating
A thin metallic coating over a regular sunglass lens creating a mirrored look. Cuts down the amount of light transmitted to the eye by reflecting much of it away and is used for intense glare.

Monel
A popular material found in many frames. It is made of 2/3 nickel and 1/3 copper. It is highly resistant to stress.

Night Vision
Night vision can be affected by high levels or prolonged exposure to sunlight. The time it takes the eyes to adapt to night vision can be significantly delayed. The use of sunglasses during the daylight hours helps to eyes to adjust to night vision more quickly.

Nylon
Frames made of nylon are lightweight, flexible and very strong. They are virtually indestructible.

Optical Quality Glass
Glass which is ground and polished to exceed standards of the American National Standards Institute (ANSI). Optical-quality glass is free of grooves, bands, seeds, or bubbles that could distort vision. As a result, this glass reduces light and glare without distorting colors. It also provides 100% UV protection.

Optyl
Plastic material made especially for eyeglass frames. It's 25% lighter than other plastics. It also has a "memory", meaning it returns to its original position if pulled out of shape.

Photochromic
Automatically lighten or darken according to the sun's brightness. Photochromic lenses must be conditioned before reaching their full capacity to change color. After several exposures to the sun, these lenses will darken fully.

Pink Lens
Pink provides excellent perception in low light conditions while allowing a tolerable level of light transmission in bright sunlight. Used to contrast objects against blue and green backgrounds. A good color for skiing and shooting.

Polarized
Polarized lenses have a filter that selectively reduces glare by permitting only one plane of light waves through. A horizontal sheet of material is laminated between two pieces of glass or plastic, or is laminated to the back of the lenses. These lenses eliminate reflective glare, especially on water or snow.

Polycarbonate
An extremely strong plastic that is often used in sunglass frames. It is also found in aircraft and motorcycle windshields.

Scratch-Resistant Coating
Scratch-resistant coatings put a hard layer on the surface of plastic lenses that resist, but do not prevent, scratching.

Serilium
A combination of polycarbonate plastic and nylon. It is sturdier than nylon with all the same durability.

Tempering
After finishing, all glass lenses must be tempered to meet federal standards for shatter resistance. Tempering adds a significant amount of strength to glass lenses, but not enough to make them break-proof.

Temple Rocking
A test performed to assess the symmetry of a sunglass frame. When placed on a flat surface the sunglass should touch the surface in four points, the right and left eye and the right and left temple tips. If the frame rocks or tips, it must be adjusted.

Titanium
A type of metal alloy that is very strong. Eyeglasses made of titanium are lightweight, durable and often hypoallergenic.

UVA Rays
There is some question about UVA rays' potential for harm to the eyes. However, they have been shown to penetrate the under layers of the skin, causing damage and contributing to the skin's aging. Therefore, it is certainly wise to require protection from them in sunglasses.

UVB Rays
UVB rays, the sunburn rays, are the ones that cause the most concern. They can cause keratitis, which is similar to a sunburn on the eye, and have been linked to the development of cataracts.

UVC Rays
UVC rays are the shortest, the most energetic, and may be the most harmful. Fortunately, they are blocked in the upper atmosphere and never reach the earth. If sunglasses protect against UVB, we can assume they protect against any possible exposure to UVC.

Yellow Lens
Yellow lenses are a long time standard in the ski industry. Provides excellent depth perception and contrast in low light. Ideal for shooting, skiing, and fast-reaction sports.

Zyl
Cellulose acetate material that is hand-cut and polished to a natural sheen rather than painted. Zyl is a top-quality ophthalmic material that holds all adjustments.