Abstract: A system such as a head-mounted device may have left and right displays for displaying images. The images may be presented to left and right eye boxes through left and right fixed (non-removable) lenses and corresponding left and right removable vision correction lenses. The left and right fixed lenses may be supported by left and right fixed lens supports to which the left and right displays are mounted, respectively. To removably attach the vision correction lenses to the fixed lenses, the fixed lens supports and vision correction lenses may be provided with bayonet mounts. The bayonet mounts may have push-and-turn structures such as pins that mate with corresponding slots.