Understanding AND Working with
Rimless Eyewear

A Comprehensive Continuing Education Supplement on Rimless Craft and Technology

The Newest Technologies in Non-Rimmed Eyewear

A Review of the Materials and Manufacturing Technologies Currently Available in Rimless Eyewear.

By Jackie O’Keefe, LDO

While the exact date of the origin of rimless eyewear is not clear, it is safe to say that it has been around for centuries, perhaps as long as 600 years. History indicates that in 1824, a young Austrian named J.F. Voigtlander marketed rimless glasses in Vienna. Several years later, the style evolved from a single lens to two lenses joined by a metal bridge (What Man Devised That He Might See, Richard Drewry, Jr., MD, eye.utmem.edu/history/glass.html). As the style developed further, temples became a popular inclusion.

During its long history, rimless eyewear has enjoyed periods of renewed discovery and popularity. For example, around the turn of the 20th century, rimless eyewear was a fashionable item. This continued until the mid-20th century when plastic acetate frames became the rage. Rimless eyewear was rediscovered in the later part of the century, and remains a hot item in today’s eyewear market.

One of the great attractions of rimless eyewear is its ever-changing technology. At the turn of the 20th century, rimless eyewear was a flimsy contraption that used cautiously drilled glass lenses, and was perched precariously on the wearer’s nose and tops of the ears. Mounting materials consisted of steel and nickel silver for lower-end products. Gold and silver with ornate engraving was used on the upper end. Styling tended to be conservative with rounds, ovals, and ovoids as the prime choices. Men and women commonly wore similar shapes and designs, and variety in mountings was limited.

All that has changed. Today rimless eyewear comes in a plethora of materials, designs, colors, shapes, and sizes. It comes with countless options like screwless hinges, compression fittings, and floating chassis. It uses technologies our grandparents would have found nearly unbelievable. Here’s a look at the fundamentals of rimless eyewear and the latest technology in this terrific category.

What Makes Eyewear Rimless?
Let’s start with what rimless is not … it’s not a frame. The word frame means that the eyewire (or eyerim if it’s a plastic frame) surrounds the lens like a picture frame surrounds a photograph or painting. Lenses are inserted into a frame. That’s why rimless eyewear doesn’t have eyewires. Instead, the structure of a rimless on which the lenses articulate is known as a mounting. The name “mounting” comes from the fact that the lenses are “laid on top of” or “mounted onto” the rimless mounting with some method of attachment like screws and nuts, tension, compression, etc.

There are two fundamental classifications of rimless mountings, full (also known as three-piece) and semi-rimless. Full rimless mountings have a bridge and two endpieces that attach to the lenses. The temples are attached to the endpieces. In a semi-rimless mounting, a bar or lens arm is fitted behind a portion of the lens (usually the top portion) onto which the temples are attached. Of course there are numerous variations on these fundamental themes.

Rimless Mountings
The traditional three-piece rimless has two holes drilled into each lens although variations of this mounting design abound. Screws, tension, cement, or other securing methods are used to keep the lenses in place (see “Innovations in Rimless Mountings”). In addition, mountings with only one hole, or as many as four per lens, can be found.

Semi-rimless eyewear features lenses that are attached either with screws, hardware, cement, a thin nylon cord, or other systems. A unique type of semi-rimless known as a Supra has a single arm onto which the lenses are cemented. Cord-mounted semi-rimless mountings are popular. In this mounting, the lenses are grooved around their circumference. This is where a thin nylon monofilament line is placed to secure them.

During its long history, rimless eyewear has enjoyed periods of renewed discovery and popularity.  

Rimway-style mountings feature a bridge with an arm extending from both sides. These arms are hidden behind the tops of both lenses and are used for attaching the lenses on the nasal and temporal sides. They also provide additional support for the lenses. The temples are attached to endpieces at the end of the arms.

Numont mountings also have an arm across the top of the mounting, but the unique feature for this product is that the lenses are attached only at the bridge. In other words, the lenses are not secured on the temporal side. As a result, the lenses seem suspended in front of the mounting.


Solutions for High-Powered Rimless Lenses

High Minus—Use extended endpieces that help the mounting’s front offer the total width the patient needs. This enables you to use smaller lenses. Round off the lenses’ thicker corners by rolling and polishing slightly. Fit the lenses as closely as possible to the eyes and use a wider bridge if necessary. Suggest higher index lenses that are thinner and lighter. The best shapes are round or oval. These help reduce lens thickness and overall weight. Offer lightweight mountings like stainless steel and titanium.

High Plus—Use smaller eyesizes and avoid unusual shapes and square corners. Suggest lens shapes that have a smaller effective diameter (ED). Fit the lenses as close as possible to the eyes. Make sure the bridge of the mounting has longer pad arms to accommodate the additional thickness at the nasal on high-plus lenses. Recommend aspheric front surface lenses because of their flatter design. Offer lightweight frames that are strong like titanium and copper beryllium.


Securing Lenses
Rimless and semi-rimless mountings that use drilled lenses are called drill mounts. The most popular way to secure drill-mounted lenses is with screws. To do this, holes are drilled through the lenses, screws are placed though the holes, fitted into the bridge and endpieces, then screwed down until secure.

Traditional rimless lenses have two holes per lens, one on the temporal side, one on the nasal side. Usually the screw is inserted from the front of the lens and a hex nut is used to secure the screw from the backside. Others place the screw from the back side and use a decorative nut on the front. A washer is often used just under the head of the screw to keep the screw snug and hold it in place. It also serves to avoid damage around the drilled hole.

More traditional styles sport a bridge and endpieces that have a flat piece attached which fits snug and flat along the outer lens edges on the temporal and nasal sides. These flat attachments are known as collars. The collars prevent the lenses from rotating or moving when mounted. Other types of mounts use a tongue (a “flap” of frame material) that wraps around the front and/or back side of the lens, covering the area where the screw comes through. A screw is inserted through the tongue and a hex nut is used to secure the lens. There are many mountings that use both tongues and collars to hold their lenses in place.

Screwless Endpieces
Some of the most advanced technology in rimless eyewear is in the endpieces. For example, the traditional hinge has been replaced with a variety of mechanisms like a ball around which the endpiece swivels. Another uses a post for rotation of the endpiece.

Another exceptional innovation is the floating temple. In this technology, premium metals like titanium are made flat and thin thereby allowing them to be highly flexible. The fronts of the temples are secured to the lenses and the temples literally float freely.

Materials Technology
One of the factors that has made rimless eyewear so popular is the use of premium mounting materials. These materials have led the way in rimless eyewear innovation because they are feature-rich, and patients have recognized their benefits and value.

Three-piece rimless mountings don’t confine the ophthalmic professional or patient, as do rimmed eyewear styles.  

Titanium is a prime example. Titanium is a lightweight, durable, and strong metal that is hypoallergenic and corrosion free. This makes it an excellent rimless material. In its 100% pure form, it’s tough. For those who want durability in a lightweight mounting, pure titanium is the answer. Beta titanium is an alloy of titanium composed of 74% titanium, 22% vanadium, and 4% aluminum. In addition to being lightweight and strong, it’s flexible. That means it “gives” during the stresses of wear, and also makes the material easy to adjust. It’s also hypoallergenic. Memory titanium’s flexibility is a wonder to see. A temple made from it can literally be twisted around your finger, and then unraveled to return to its original configuration. Marchon’s Flexon is the most notable memory metal.

One of titanium’s great features is that it can be made very thin and flexible. Silhouette Optical Ltd.’s Mininal Art Collection is a prime example of how thin and flexible titanium (in this case beta titanium) can be with its floating temples and ultra-thin front.

Stainless steel is another popular premium mounting material. Constructed from a combination of nickel and chrome, it is strong, durable, lightweight, corrosion-free, and hypoallergenic. Like titanium, it can be made very thin while still maintaining its structural integrity. This makes it ideal for those minimalist rimless styles so popular today such as Bollé’s Valorium, an ultra-lightweight stainless steel that is ergonomically engineered.

Copper beryllium, magnesium, genium, and vanadium have also become contributors to the premium mounting material scene although usually as part of an alloy. Often, these materials offer the thinness and lightweight of premium metals at a lower cost.

Magnesium, for example, which is used in rimless styles by Allison Eyewear and Oakley, Inc., is 30% lighter than titanium and 67% as dense as aluminum. These materials offer lightweight, durability, strength, and hypoallergenic qualities.

While many of today’s rimless are made of metal, plastic mountings are also becoming popular. High-tech polymers like acetate, nylon, nibrodal, crystalline amide, Grilamid TRLX, Micro-Cristalline Polyamide, trogamid, ceramic polymers, and synthetic SPX and SPXng (both proprietary materials from Silhouette Optical Ltd.) are good examples.

Traditional zyl (cellulose acetate) has gone upscale with premium Italian zyl that is supple and colorful, and retains the light and comfortable qualities of traditional zyl. Some of Zyloware Corporation’s Via Spiga styles have double laminate colorings handmade from Italian zyl.

Polyamide is made from a blend of nylons and features durability, reduced weight, and flexibility, and is considered hypoallergenic. Made by injection molding, it is particularly good with translucent colors and is highly scratch-resistant.

Silhouette’s proprietary SPXng (ng stands for “next generation”), is a microcrystalline polyamid that is extremely flexible and heat resistant. It has a memory to help it retain its shape but is easy to adjust using minimal heat. While the base color of the material is clear, when an opaque color flash is placed over it, the result is luminous incandescent color hues like green, blue violet, and blush.

Grilamid is a lightweight frame material designed to be rugged, resilient, highly impact resistant, and comfortable. It’s a good match for rimless eyewear, especially when used for sunwear. It can take the toughest treatment a patient can give it and maintain its structural integrity. Its light weight also makes it an ideal rimless material.

Rimless as Fashion
Unlike rimmed eyewear, rimless eyewear is nearly limitless in the shapes, sizes, and designs it can manifest. From classic round and octagonal shapes to customized unconventional and unique shapes, there’s more versatility in rimless eyewear than any other form of eyewear.

Three-piece rimless mountings don’t confine the ophthalmic professional or patient, as do rimmed eyewear styles. That’s because you can place small, large, or any size lens between the bridge and endpieces. This creates great flexibility in the designing process and also allows the ophthalmic professional to only have to stock one size mounting.

Utilizing three-piece rimless mountings, the ophthalmic professional can use creativity to achieve any look a patient may want. For instance, the aviator shape is ideal for a sporty look while the pillowed rectangle is more casual in design. The more fashion-forward individual may desire a retro look or shapes with sharp angles that stand out in any crowd.

Color Considerations
Manufacturers have discovered the allure of color in rimless eyewear. Unlike in years past, today’s rimless eyewear uses color as a fashion statement. Technology has allowed manufacturers to create a spectrum of colors in finishes from shiny bright to satin and matte.

One of the notable successes in rimless mounting coloring is with titanium. By anodizing or ionizing the material by subjecting it to electrical currents, the color is found throughout the component. This creates the highest level of color stability and does not wear away or peel off in time. The stunning colors range from pale pastels to bold and vibrant hues.

Making rimless eyewear unique includes selecting and combining unique colors too—not just the temples and front, but the endpieces and screws as well. Some eyewear manufacturers have even begun producing multi-colored mountings. Other colorful options are to offer a discreet touch of color by using different colored screws or going wild with multi-colors. The combinations are virtually endless. Higher-end frames may even be handpainted for an exclusive look.

New Options in Lens Materials
Rimless eyewear can be challenging when fabricating and adjusting the final product. Lenses may chip, flake, or break—especially around the mounting hole. That’s why glass lenses, along with their weight, do not make good options for rimless styles.

While CR-39® was a favored lens material for all kinds of eyewear for many years, it is no longer considered a good choice for rimless eyewear. One reason stems from its low index of refraction. In fact, CR-39 has the lowest index of all plastic lenses materials, resulting in the thickest lens profile for a given prescription. In a rimless design, that’s exactly what you don’t want. Also, CR-39’s impact resistance is inferior to a number of other plastic lens choices. And since rimless mountings can be fragile because the lenses are drilled, notched, or somehow secured without a rim, impact resistance is a big issue.

To respond to these unique challenges, many ophthalmic professionals are looking for good lens options and many ophthalmic lens providers are introducing lens materials that they position as “rimless eyewear friendly.”

Polycarbonate is very rimless friendly. It is a lightweight, strong, and incredibly impact-resistant lens material. Polycarbonate is also a bit soft, which makes it excellent for working with rimless mountings. It drills easily and won’t flake and chip around the hole like glass or some other plastic lens materials. Polycarbonate’s light weight makes it a perfect teammate for ultra-thin rimless mountings too. Optima, Inc. has even developed a stress-free polycarbonate—Resolution®. This lens eliminates birefringence—an optical phenomenon referring to double refraction (commonplace among other polycarbonate products)—which can be created from internal stress.

Another great thing about polycarbonate is that it is available in nearly every lens style imaginable. That means you can recommend it to all your patients without having to worry that the style you ordered may not be produced. Patients and ophthalmic professionals also appreciate that polycarbonate absorbs 100% of UVA and UVB radiations. And of course, polycarbonate is a high index material too (index 1.59), so that lenses made from it will have a nice, thin profile.

Trivex is another terrific rimless-friendly lens material option. Brought to the ophthalmic industry by PPG Industries, the lenses are currently available from HOYA VISION CARE, North America, Younger Optics, and Thai Polymer Lens Co. HOYA markets Trivex lenses under the Phoenix brand, and Younger’s lens line is Trilogy. Trivex’s impact resistance rivals polycarbonate—the material is strong, and is even lighter than polycarbonate. In addition, its Abbe value is higher than polycarbonate, which may help some patients who are sensitive to color aberration. Trivex’s unique production process eliminates internal stress in the lens. In other words, if you were to place the lens into a polariscope, you wouldn’t see any pattern or color in the lens (color indicates internal stress).

Trivex takes drilling well and won’t flake or chip during the process. Its 1.53 index makes it a premium option over CR-39 and it is available in a number of lens styles, including single vision aspherics and progressives. Trivex also absorbs 100% UVA and UVB radiations.

Other High-Index Materials
Patients today appreciate the thinness and lightness that high-index lenses represent, particularly if their higher prescriptions provided them with just the opposite in the past. And rimless eyewear is fully complemented by thin and light lenses. Plastic mid-index lenses are available for moderate prescriptions and products with an index of 1.60 and higher are available too. Within these materials you’ll find a full range of lens styles and lens options.

Some high index materials are well suited for rimless use. For example, Seiko Optical Products’ 1.67 lenses are composed of MR-10 resin. This special resin is ideal for rimless mounts because it drills/notches well and provides a cleaner edge when polished. It also can withstand the stress of adjustments. Its 1.67 index of refraction makes it one of the highest in the plastic lens family. This means it will provide a thin lens profile and lightweight lenses.

Teaming it with an aspheric design creates the ideal rimless option for the patient. In fact, many low-powered prescription wearers now opt for higher index lens materials like MR-10 for their eyewear due to these benefits.

Enhancing the Look
Rimless eyewear is about a minimalist look—less is more. Hence, the more the dispenser can do to enhance that look, the greater the patient’s satisfaction. Adding an anti-reflective (AR) coating to rimless lenses—making the eyewear virtually invisible—is an obvious, significant add-on. But keep in mind that the patient will also want lenses that are resistant to smudges or relatively easy to keep clean. There are a number of lens cleaners on the market today designed expressly for AR lens maintenance.

For those who actually want to go with a more conspicuous look, custom lens edge treatments can accentuate the final rimless eyewear product. Try applying color around the flat edge of the lenses, or groove the lenses and add color to them. Since rimless eyewear has a tendency to disappear on the face, tinting the lenses with a light café tint makes them more noticeable. Gradient tints are an eye-catcher, too. Light mirrored coatings are also a good choice, especially if they have a single or multiple colored mirror.

Rimless eyewear has come a long way from J.F. Voigtlander’s early designs. Today’s rimless eyewear products represent the best styling, materials, and construction modern technology provides—but who knows what’s next?

Jackie O’Keefe is a licensed optician. She is currently employed at Coastal Vision in Virginia Beach, VA.

Issue Date: July/August 2003
Expiration Date: January 31, 2004

This course has been approved for one hour of continuing education credit by the American Board of Opticianry (ABO).

Learning Objectives:

Upon completion of this program, the participant should be able to:

  1. Explain the various types of rimless mountings and how they differ.
  2. List the features and benefits of today’s premium mounting materials.
  3. Identify the lens materials best suited for rimless eyewear and explain why each is a good choice.

Please consult your state licensing board to assure that this CE counts toward your requirement for maintaining licensure.