A device and method for measuring the pantoscopic tilt of a lens installed in a frame, the device comprising an orientation sensor for measuring pantoscopic tilt and an attachment member to attach the device to a lens. The method comprises marking a center of the pupil on a lens while a patient is wearing the spectacles, attaching a measurement device at the marked center of the pupil point and while the device is attached to the lens, reading the pantoscopic tilt value from the device while the patient is wearing the spectacles in a natural position of the head for looking at the horizon.