| 主权项 |
1. A tangible medium configured for programming a processor to produce on a display a viewing target for a visual acuity or a refraction measurement of a test subject, wherein the viewing target comprises:
(a) at least one line comprising a width dimension that is within a range that includes a resolution limit width (hereinafter “RLW”) of a test subject visual acuity, and an adjustable length dimension that is initially set within said range that includes said RLW of the test subject visual acuity and is adjustable to other values; (b) a base, comprising one or more further lines including at least one of said one or more further lines approximately intersecting said at least one line, wherein a number of said one or more further lines is adjustable; (c) wherein the viewing target includes an elliptical, circular, semi-circular, oval, square, rectangle, hexagon, octagon or other polygon, or a curved regular or irregular shape; and (d) wherein each of one or more of color, brightness, or gray level of the at least one line or of the one or more further lines, or both, is adjustable; and (e) wherein the one or more of the color, brightness, or the gray level of the background within which the viewing target is displayed is also adjustable, (f) whereby in performing a visual acuity measurement of a test subject, the length dimension of the line is adjustable in increments small enough to effectively approximate the visual acuity of the test subject by determining a shortest resolvable line and a next smaller line that is not resolvable by the test subject. |
