Measurement device and measurement method

A measurement apparatus for measuring a subject's eyelid position, comprising:

• a lighting device configured to irradiate band-like linear light extending across the subject's upper to lower eyelids;
• an imaging device having an optical axis on a plane for which a plane including an extending bundle of rays of the light is rotated by a predetermined angle around an axis along a direction in which the band-like linear light extends across the subject's upper and lower eyelids;
• and
• at least one processor having instructions stored in a non-transitory memory device, that, when executed by the at least one processor, cause the measurement apparatus to perform operations comprising:
• obtaining height information indicating a height in the direction of irradiation of the light, based on a position of an optical image in an image imaged by the imaging device, and
• measuring the eyelid position based on the height information,
• wherein the height information is obtained based on the position of an optical image in a direction perpendicular to a direction in which the optical image extends,
• wherein the imaging device is configured to capture the image including a first scattered light image of the subject's eyelid and a second scattered light image of the subject's sclera, and
• the at least one processor causes the measurement apparatus to obtain height information indicating a height in the direction of irradiation of the light, based on a horizontal shift amount between a position of the first scattered light image and a position of the second scattered light image in the direction perpendicular to the direction in which the optical image extends.