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 Eyeglass Frames

What are the parts of an eyeglass frame?
What materials are used to make eyeglass frames?

Modern eyeglass frames are available in a huge variety of styles, sizes, and materials. For those who are fashion conscious, there are dozens of designer styles. Children's and safety frames are now available in materials that are nearly indestructible. New materials and design technology have made frames more lightweight and comfortable. Good quality frames are now available in all price ranges, too. An experienced, knowledgeable optician can help when selecting a quality frame that looks good and fits well.

What are the parts of an eyeglass frame?

Here are some of the frame terms you may hear when being fitted for a new pair of eyeglasses:

Frame front: Front part of the eyeglass frame that holds the lenses in place and bridges the top of the nose.

Eye wires (rims): Part of the frame front into which the lenses are inserted.

Bridge: The area between the lenses that goes over the nose and supports 90 percent of the weight of the eyeglasses.

  • A keyhole bridge is shaped like an old-fashioned keyhole and rests on the sides of the upper part of the nose. This style is for those with small or flat nose bridges.
  • A saddle bridge is shaped like a saddle and spreads the weight of the frame across the sides and the top of the nose. This style works well for heavy glasses or for those who are sensitive to pressure.
  • An adjustable bridge includes nose pads that can be adjusted for fit and comfort.
  • A double bridge has a reinforcing bar over the top of the bridge.

End pieces: Extensions of the frame front to which the temples are attached.

Hinges: Part of the frame that connects the frame front to the temples and allows the temples to swing.

Temples: Parts of the frame that extend over and/or behind the ears to help hold the frame in place.

  • Skull temples are the most popular for plastic frames. They are bent down slightly over the ear and follow the contour of the skull.
  • Comfort-cable temples hook behind the ear with a flexible metal cable and are good for children's glasses and for sport safety glasses.
  • Riding bow temples are similar to comfort-cables, except they are rigid and made of plastic.
  • Spring-hinged temples include hidden springs in the hinges that help keep the frame from slipping. They are sometimes more expensive, but usually more resistant to breakage.
  • Library (or paddle) temples are straight, so they can be slipped on and off easily. They are often used in reading glasses.

Nose pads: Plastic pieces that may be attached directly to the frame or to pad arms. They help keep the frame in its proper position.

Pad arms: Attachments that hold the nose pads in place and allow adjustments to help conform to the patient's bridge.

Top bar: A reinforcing bar that crosses the top of the glasses on some metal frames, popular in aviator glasses.

Temple tips: Plastic coatings that often cover the ends of the temples behind and/or over the ears.

Rimless frames (or mountings): The temples and bridge attach by mountings directly to the lenses without the use of eyewires or rims.

What materials are used to make eyeglass frames?

The materials used in the production of modern eyeglass frames are plastic, metal, or a combination of the two (composites). Manufacturers select materials that are cost effective, adjust easily, offer safety and workability, hold the lenses properly, and resist breakage, corrosion, and heat. Here are brief descriptions of popular frame materials.

Plastics

Cellulose acetate (zylonite): The most commonly used plastic in eyeglass frames, cellulose acetate is relatively inexpensive, easy to work with, and comes in a wide variety of colors, textures, and patterns. The material is easily adjusted but tends to get brittle with age.

Cellulose proprionate: This is a lightweight material that can be injection molded making it ideal for intricate designs. Care must be taken when heating and adjusting frames made of this material because it will shrink and ruin with overheating.

Kevlar: Developed by DuPont for use in bulletproof vests, this plastic can withstand high impact such as that experienced in sporting events. The material is limited because it will not shrink or stretch, and it comes in few colors.

Nylon: Many sports and safety glasses are made of nylon because it is virtually unbreakable and relatively lightweight. The material is, however, difficult to adjust and can be manufactured only in darker colors. It can also become brittle over time.

Optyl: This material is somewhat lighter in weight than cellulose acetate and is hypoallergenic, an advantage to skin-sensitive patients. Frames made of optyl are more difficult to adjust because the material can return to its original molded shape, and the frames may break easily if not heated properly.

Polycarbonate: Polycarbonate is 10 times more impact-resistant than conventional plastic or glass and is the material of choice for children's, sports, and safety glasses. Polycarbonate lenses are thinner and lighter than conventional plastic or glass lenses, and the material comes with built-in ultraviolet protection.

Metals

Aluminum: Although very lightweight, aluminum is difficult to solder or weld, limiting its adaptability to different designs.

Cobalt: Usually used as part of a metal alloy, cobalt appears in high-quality frames that can be made lightweight, durable, flexible, and thin. It can also be successfully coated with a variety of colors, but is very expensive and consequently limited in use.

Monel: Monel is one of the most popular materials used in metal frames because it can be hammered into many shapes without losing its strength. It can also be made in various colors.

Nickel silver: This is a common material used in hinges, end pieces, and heavy bridges, and for the inner core of temples. It is more brittle than several other metals, making it less suited to the slender frames so popular today.

Phosphor bronze: This flexible alloy is about 95 percent copper, making it a good choice for temples.

Stainless steel: Stainless steel is one of the most corrosion-resistant metals, but is difficult to work with in the manufacturing process.

Trilam: This product is lightweight, however it has a memory, which can make frame adjustments difficult.

Composites

Carbon fiber graphite (CFG): CFG is a material made of nylon and carbon that provides the endurance of metal frames but is thin and lightweight. Although the material is black in its natural state, it is now available in a wide range of colors.

Copolyamide (MXP7): This material is a blend of nylon manufactured for frame-injection molding. The material is strong, lightweight, and durable, and it retains its shape unless heated.

Flexon7: Flexon7 is a proprietary material made from a titanium-based alloy with a high "memory" factor that enables a twisted frame to return to its original shape. In addition to making frames extremely durable, the Flexon material holds adjustments longer and is lighter in weight than traditional metal frames.

Titanium Ti-227: Titanium Ti-227 is nearly 50 percent lighter than most metal frame materials. It is hypoallergenic, noncorrosive, and one-third stronger than steel, making it an extremely desirable material for manufacturing frames. It's also difficult and expensive to extract and refine this abundant material.


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