Lens, lens blank, and eyewear

A lens for eyewear, the lens comprising:

• a first transparent substrate that includes a diffraction region where a plurality of protruding strips and a plurality of grooves are coaxially and alternately formed;
• a second transparent substrate that faces the first transparent substrate in a predetermined direction;
• a liquid crystal layer that is provided in a space between the diffraction region and the second transparent substrate;
• and
• a first transparent electrode and a second transparent electrode that apply a voltage to the liquid crystal layer, wherein:
• the diffraction region includes a first diffraction region and a second diffraction region that is located in at least a part of a region different from the first diffraction region, and
• the space includes groove spaces and a communication space, the groove spaces lying between the grooves and the second transparent substrate, the communication space lying between at least a part of the protruding strips and the second transparent substrate in the second diffraction region and communicating between adjacent ones of the groove spaces with one another.