What Is Drill-Mount Construction?
Drill-mount construction is the defining feature of true rimless glasses. In this construction method, the lens itself has holes drilled through it at precise locations, and the frame hardware — bridge and temple arms — attach directly to the lens through these holes. There is no surrounding rim holding the lens in place. The lens is structurally self-supporting, held only at the two drill points per lens.
The Anatomy of a Drill Mount
Each drill-mount point consists of: a threaded barrel insert that fits through the lens hole, a backing washer on the opposite side, a screw that clamps the assembly together, and the frame component (bridge side or temple hinge) that attaches to the barrel. The quality of each of these components determines the longevity and safety of the mount. Cheap alloy screws corrode and strip; quality titanium hardware holds indefinitely.
How the Holes Are Made
Lens drilling is done by an optician or lens lab using a specialized drill press designed for ophthalmic lenses. The drill bit is precisely sized to create a clean hole without lens cracking — too small and the hardware will be forced in, stressing the lens; too large and the mount will be loose and vibrate. The drill point location is mapped from the frame’s bridge width and the patient’s pupillary distance to ensure optical centers align correctly.
Alternatives to Drill Mount (and Why They’re Inferior)
Not all “rimless” glasses use drill mounts. Some use groove mounts — a channel carved around the lens edge that a wire slides into, common in half-rimless designs. Some use clip systems — plastic or metal clips that grip the lens edge. Both of these fail The Rimless Standard™: groove mounts have a surrounding element (the wire), and clip systems frequently slip and rotate the lens. Only drill-mount provides the true lens-as-frame architecture that defines genuine rimless glasses.
Maintenance of Drill-Mount Glasses
The only maintenance drill-mount rimless glasses require is periodic screw tightening — typically every 4-6 months for everyday wearers. An optician does this in 2 minutes with a small screwdriver. Do not over-tighten — the correct torque is snug but not forced. An overtightened screw can crack the lens from the drill point. If a screw is stripped or the barrel is corroded, have an optician replace the hardware — a $15-$30 repair that extends the frame life indefinitely.