A measurement device for measuring a characteristic reading distance of an individual in a natural posture for near vision, includes a movable reading medium presenting a plane display portion suitable for displaying signs and a measurement subassembly including at least one ultrasound emitter member and at least one ultrasound receiver member. The emitter and receiver members are carried by the reading medium, and at least one of the members, referred to as the first measurement member possesses a measurement axis along which emission or reception by the first measurement member is privileged and that is inclined relative to the plane of the display portion by an angle lying in the range 10 degrees to 80 degrees or that is inclinable relative to this plane of the display portion at least over an angular range extending from 10 degrees to 80 degrees.