Buying Guide: Glossary of Eyewear Terms

Acetate Type of plastic often used in eyeglass frames and lenses.

Acrylic Plastic Lenses made of this will weight less and are the least expensive. They are soft and wills scratch very easily and must be specially treated to block UV rays.

ANSI The American National Standards Institute has served in its capacity as administrator and coordinator of the United States private sector voluntary standardization system for more than 80 years. Founded in 1918 by five engineering societies and three government agencies, the Institute remains a private, nonprofit membership organization supported by a diverse constituency of private and public sector organizations.

Anti-reflective (AR) Coating Thin layer(s) applied to a lens to reduce the amount of reflected light and glare that reaches the eye.

Authentic Rx Lens Comes directly from the frame manufacturer, thereby giving you all the features of that manufacturer's specialty lens with your custom prescription. Often, the manufacturer's logo is etched onto the lens as a symbol of authenticity. Please note these are custom orders and are NON-REFUNDABLE.

Aviator Glasses Eyewear like those that aviators used to wear; they usually have a metal frame and large, tinted lenses.

Blue Light A portion of sunlight which is blocked by yellow or amber lenses. Some people feel that filtering out blue light increases contrast, and makes distant objects appear more distinct.

Bridge The part of sunglasses that extends across the nose.

Cable Temple Style of eyeglasses that wraps around the ear, to keep them well-fastened.

Cellulose Acetate Zyl This plastic is medium-weight, flexible, and strong. It's adjustable with heat and most zyl frame temples have metal reinforcements that will make them stronger.

Clip-on Type of glasses that attaches to your regular glasses, such as clip-on sunglasses.

CR-39 Optical quality plastic, made of hard resin, is considered the best plastic for lenses. It weights half as much as glass and exceeds FDA requirements for impact-resistance.

Flash Coating A highly reflective coating, which greatly reduces the amount of light that reaches your eyes. Generally applied over a dark sunglasses lens, but can be applied over any base color. Mirror coated lenses absorb anywhere from 10% to 60% more light than uncoated lenses. These are good for higher altitudes, sand, water and snow. Although the most common are the silver, gold and copper metallic coatings, you will find many colors available nowadays. *Also called Mirror Coating

Glare Caused by a direct light source (the sun) or is reflected from a surface (roadway, water). Your eyes can be subjected to more than 10 times the level of light you need to see. When it reaches these levels it will become physically painful.

Gradient Coating Permanently shaded from top to bottom. A double-gradient lens is dark at the top and bottom and lighter in the middle.

Graphite Combines carbon and fiberglass materials, it is extremely lightweight and strong.

Grilamid In theory, a rugged, resilient frame material that's specially formulated for flex, impact strength and dimensional stability. In practice, it's tough enough to withstand the most aggressive physical punishment your body is willing to endure.

Ground and Polished Some non-prescription glasses are ground and polished when they are manufactured to improve the quality of the lenses. If glasses are not ground and polished it will not hurt your eyes.

High Index Type of lens with a higher index of refraction, meaning that light travels faster through the lens to reach the eye than with traditional glass or plastic. It is denser, so the same amount of visual correction occurs with less material (whether glass or plastic) -- so the lens can be thinner.

Hydrophilic Used in frame temples and nose pads, giving them more adhesion with high moisture. This means the more you sweat the more adhesion it delivers.

Hydrated Nylon The industry's most durable material, virtually unbreakable with memory that returns to its original shape. Providing a lightweight fit for unmatched comfort during any activity.

Impact Resistant Polycarbonate used in lenses and frames are safer than traditional materials because they aren't brittle and hold up better under impact. They tend to absorb the impact rather than shattering, but this is not a guarantee of non-breakage.

Infrared (IR) Radiation Long wavelength rays, sometimes called "heat waves". Half of the sun's energy is infrared, IR is stronger at high altitudes. Electric heaters, house radiators, and ordinary light bulbs also emit infrared energy. The rays cause the skin to feel hot and may contribute to the discomfort caused by exposure to bright light.

Megol Soft and pliable rubber, Megol gives a comfortable and slip-resistant fit.

Metal Frames Frame metals 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.

Mirror Coating A highly reflective coating, which greatly reduces the amount of light that reaches your eyes. Generally applied over a dark sunglasses lens, but can be applied over any base color. Mirror coated lenses absorb anywhere from 10% to 60% more light than uncoated lenses. These are good for higher altitudes, sand, water and snow. Although the most common are the silver, gold and copper metallic coatings, you will find many colors available nowadays. *Also called Flash Coating

Monel Durable memory nylon material, virtually unbreakable with memory that returns to its original shape.

Nylon Lightweight and durable synthetic material, derived from coal, water, and air which is very flexible.

Optically Correct Lens When looking through a non-optically correct lens, you will continually refocus due to distortion. This leads to eye strain/fatigue, causing headaches, nausea and dizziness.

Optyl A plastic material made especially for eyeglass frames. Optyl is 25% lighter than other plastics. It is hypoallergenic and has a memory, that is, it returns to its original shape if pulled out of adjustment.

Peripheral Vision The edges of your visual field. Most commonly refers to the left and right sides of your eyes.

Photochromic Coating Will automatically darken and lighten when the light changes, although the cheaper photochromic lenses wont' get very dark and take some time to adjust to different conditions. It will require conditioning the lens first, through several exposures to the sun in order to darken fully.

Polarized Lenses A filter sandwiched between the front and back surface of the lens which filters out horizontally reflected glare and allows you to see through reflected glare on the surface of water, snow, ice, glass etc. Ideal for water sports or winter sports where the water and snow increase the reflected glare. Absorbs 98% of the reflected glare.

Polycarbonate Remarkable strong plastic. It weighs the least and is the most impact-resistant making it a perfect choice for rugged sunglass frames and lenses. The lens will also offer built-in ultraviolet protection.

Protective Glasses Eyewear made with impact-resistant lenses, usually polycarbonate, that protects the eyes, especially in working situations or sports.

Safety Glasses Both the frame and lenses must pass ANSI standards. The frames are more durable than fashion frames and the lenses must be able to pass a "drop ball" test. This involves dropping a hard ball onto the lens from a certain height. If the lens cracks or shatters, it fails.

Serilium A combination of polycarbonate plastic and nylon that has the same durability as nylon, but is sturdier.

Silicon Type of flexible and comfortable plastic. because it is commonly used in nose pads in eyeglasses, people who are allergic to silicone should be aware and seek a different type of nose pad.

Spring Hinge Type of hinge on eyeglass frames that is more flexible than a regular hinge, making the frames more durable and better fitting.

Temple The "arm" of a pair of glasses, running from the ear to the lens area.

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

Ultraviolet (UV) Rays The invisible part of the light spectrum whose rays have wavelengths shorter than the violet end of the visible spectrum and longer than X-rays. UVA and UVB light are harmful to your eyes and skin. UVC are blocked in the upper atmosphere and almost never reach the earth.

Visible Light That part of the sun's energy that you can see. it is made up of a spectrum of colors; red, orange, yellow, green, blue, and violet. The eye is not equally sensitive to all of these colors. It is most sensitive to yellows and greens which it can see the best. The eye is less sensitive to reds and blues.

Wrap-around (wrap) Type of eyeglass frame that curves around the head, from the front to the side. Wrap-around sunglasses tend to offer extra sun protection because the lenses usually wrap as well.