An optical touch screen that utilizes a planar transparent sheet and that is configured to determine the position of a touch event on the transparent sheet is disclosed. Light-source elements and light-sensing elements are operably disposed at a perimeter of the transparent sheet. Light is detected over lines-of-sight between the light-source elements and the light-sensing elements. Attenuated lines-of-sight due to the touch event are determined. Central lines are established based on the attenuated lines-of-sight. The locations of central-line intersections are then established. The average of the locations of the central-line intersections is then used to establish the location of the touch event.