Rimless (Eyeglass Frames)

Nothing surrounds the lens. A bridge and two endpieces bolt directly through holes drilled in each lens. The trade calls this a three piece mount: two lenses plus one bridge assembly with the temples hung off it. Load a rim would normally spread around the whole edge travels through those small holes instead. That concentration explains every strength and every weakness of the design.

Drilling narrows the lens list sharply. Polycarbonate and Trivex tolerate a hole because they resist cracking under stress; CR-39 and glass chip at the drill point and spider outward from it, so labs decline to use them. Mount geometry then matters more than anything else on the frame. A slotted mount with a compression bushing spreads pressure over a wider bearing area, while a plain screw through a single round hole concentrates it and lets the lens rotate until the hole wears oval. Lens shape is free, since no rim has to be manufactured to match it, but a strong prescription puts its full edge thickness on display with nothing to hide behind.

Semi rimless frames keep a top rim and use cord below, splitting the difference on both weight and durability. At the far end sits the closed rim, heavier and much harder to break. Titanium turns up constantly in this construction, because the parts are tiny, must not corrode against sweat, and need to stay adjusted; acetate barely appears at all, having no way to grip a lens without a rim.

Low visible weight, formal work, and a wish for the correction rather than the frame to be the thing people see all point here. Mild to moderate prescriptions give the cleanest result, and a lab can polish the exposed lens edge to reduce the way it catches light.

Hold the bridge and twist each lens gently at its outer corner. Any rotation at all means the mount is not clamping properly. Favor a second post or a slot that stops rotation over one lonely round hole. Tighten the screws twice a year, and clean these by holding the bridge, never by gripping one lens and rubbing the other.