Which two types of bridges are commonly found on a spectacle frame?

Keyhole and saddle bridges are two common designs found on spectacle frames, each serving distinct purposes in terms of fit and comfort.

The keyhole bridge is specifically designed to accommodate the nose anatomy, offering a notch in the center that allows a comfortable resting place for the frame on the nasal bridge. This design helps in distributing the weight of the glasses across the sides of the nose rather than concentrating it on a single point, which can enhance comfort, especially for prolonged wear.

On the other hand, the saddle bridge is shaped much like the saddle of a horse and is designed to provide a smooth, continuous surface across the nose. It typically has a wider surface area to support the frame, providing stability and both comfort and an appealing aesthetic.

Together, these bridges are commonly utilized in various styles of eyewear, ensuring that frames fit securely while maintaining comfort for the wearer. Other options may include different bridge shapes but might not be as standard in typical spectacle designs.