Provide a valuable resource to your clients or customers by linking to this resource page. Just place the following link on your website.
A pin bevel is a special type of edge that an optical lab cuts onto a prescription lens. This edge is made specifically for mounting a lens into a semi-rimless frame. A semi-rimless frame is one that has a metal or plastic rim on top, but is open on the bottom. The pin bevel creates a tiny groove for the nylon cord that holds the bottom of the lens in place.
read more about pin bevel on an ophthalmic lens ...A semi-rimless frame uses a combination of a traditional frame top and a thin, strong nylon cord on the bottom. To fit this style, a lens needs two different types of edges. The top of the lens has a standard "V-shaped" bevel to fit in the frame's groove. The bottom of the lens has the special pin bevel, which creates a small shelf for the nylon cord to rest in, holding it securely.
Creating a pin bevel is a precise job done by a modern lens edger in the lab. The machine's computer knows the exact shape of the frame. It automatically cuts a standard bevel on the top portion of the lens and then switches to cut the very fine and sharp pin bevel on the bottom portion. This tiny ridge is what prevents the smooth nylon cord from slipping off the lens.
The pin bevel is what makes the lightweight and stylish semi-rimless frame design possible. It provides a secure mounting point for the lens that is almost invisible. This creates a clean, open look that is less noticeable on the face than a full-rim frame. It is a sign of a precise and high-quality lens finishing process.
Beyond holding the nylon cord, the pin bevel serves a safety function. A lens edge that is cut perfectly flat at a 90-degree angle is very sharp and fragile. It creates a corner that is easily chipped if you accidentally bump your glasses. The pin bevel knocks off this sharp corner, creating a slightly angled or blunt edge that is much more resistant to chipping during daily wear.
The bevel itself is just a shape. The strength of the lens comes from the material. Because the bottom edge of the lens is exposed in a semi-rimless frame, it is always recommended to use a very impact-resistant material like polycarbonate or Trivex.
The nylon cord is very durable, but it can stretch or break over time. If this happens, your lens might feel loose. An optician can replace this cord for you very quickly and easily.
It is very hard to see. It is a very fine detail on the edge of the lens, and the nylon cord usually hides it from view. It is not something you would typically notice on your finished glasses.
You do not need to ask for a pin bevel by name. It is the standard, required edge for any lens going into a semi-rimless frame. This is a technical detail that the lab handles automatically. If a lens in your semi-rimless frame ever feels loose, take it to your optician so they can check the tension of the cord and ensure the lens is secure.
Semi-Rimless Mounting and Nylon Cord Lenses. All About Vision. https://www.allaboutvision.com/eyewear/eyeglasses/styles/rimless-glasses/. Accessed April 7, 2026.
Lens Edging and Mounting Types. OptiCampus. https://opticampus.opti.vision/cecourse.php?url=basic_dispensing_optics/. Accessed April 7, 2026.
Polycarbonate Lenses. All About Vision. https://www.allaboutvision.com/eyewear/eyeglasses/lenses/polycarbonate/. Accessed April 7, 2026.
Trivex Lenses. All About Vision. https://www.allaboutvision.com/eyewear/eyeglasses/lenses/trivex/. Accessed April 7, 2026.
All About Lens Surfacing. Laramy-K Independent Optical Lab. https://www.laramyk.com/resources/education/surfacing/all-about-lens-surfacing/. Accessed April 7, 2026.