Provided herein are devices, systems, methods, apparatuses, and computer program products for determining a visual acuity of a reader. The device includes a display adapted to present a first line of text to the reader and an input device adapted to receive signals corresponding to the first line of text. The device further includes a processor that is adapted to determine a reading score associated with the first line of text, generate an acuity parameter based on the reading score and the first readability vector, and determine the visual acuity of the reader based on the acuity parameter and a reference acuity parameter.