Method, use of adapted optotypes and device for determining visual acuity characteristics of a subject

A method for determining acuity-of-vision characteristics of a test person who has at least one astigmatic visual defect, comprising:

• providing visual defect data of the test person, wherein the visual defect data includes at least one cylinder axis or axial position of a required optical cylinder correction;
• selecting a preferential direction such that the preferential direction either corresponds to the cylinder axis which is assigned to the optical cylinder correction, or is rotated by 90° to this cylinder axis, or the preferential direction is derived from wavefront data using a point spread function;
• applying an optical power at least in the selected preferential direction;
• displaying at least one adapted visual sign which has a directional feature, wherein the adapted visual sign is displayed aligned such that its directional feature is arranged in parallel to the preferential direction;
• and
• determining the acuity-of-vision characteristics of the test person for the selected preferential direction, taking into account at least one dimension of the directional feature of the adapted visual sign and the applied optical power.

An apparatus for determining acuity-of-vision characteristics of a test person who has at least one astigmatic visual defect, comprising:

• a selection module configured to select a preferential direction, wherein this preferential direction either corresponds to a cylinder axis or axial position which is assigned to an optical cylinder correction required by the test person, or is rotated by 90° to this cylinder axis, or the preferential direction is derived from wavefront data using a point spread function;
• a refraction unit configured to apply an optical power to the test person in the selected preferential direction;
• a display module having a display and configured to display at least one adapted visual sign having a directional feature on the display such that the directional feature of the adapted visual sign is arranged in parallel to the preferential direction;
• and
• an acuity-of-vision characteristics determination module configured to determine the acuity-of-vision characteristics of the test person for the selected preferential direction, taking into account at least one dimension of the directional feature of the adapted visual sign and the applied optical power.