The method include: (a) displaying at least one dynamic target image of at least one sign over a display area; (b) receiving subjective feedback from the subject indicating that the subject is positioned at a maximum distance of best acuity (MDBA) from the target image, wherein the MDBA is the maximum distance in which the subject recognizes the sign; (c) measuring one or more parameter associated with distance, during the time the subject has reached the MDBA distance, using at least one sensor; (d) estimating the MDBA by estimating the distance between the eye of the subject and the display area in which the target image is displayed by using the sensor data and (e) calculating the refractive error of the eye according to the estimated MDBA and characteristics of the target image.