A method for performing an astigmatism power test using a computing device having a screen for displaying images relating to said astigmatism power test, said method comprising the steps of: - determining, by said device, using feedback input received from a user, a calibrated rotation of a fifth elongated image (26, 37) displayed on said screen such that in a calibrated position said user perceives said displayed fifth elongated image (26, 37) substantially the most clear; - determining, by said device, an angle of astigmatism based on said calibrated rotation of said fifth elongated image; - calibrating, by said device, using feedback input received from said user, a resolution acuity of said user irrespective of said astigmatism by amending a thickness of at least one first elongated image comprising one or more lines displayed at substantially +45° of said determined angle of astigmatism and/or amending a thickness of at least one second elongated image comprising one or more lines displayed at substantially -45° of said determined angle of astigmatism such that in a calibrated position said user is just able to recognize said at least one first elongated image and/or said at least one second elongated image; - thickening and/or blurring, by said device, using feedback input received from said user, at least one third elongated image with respect to at least one fourth elongated image, wherein said at least one third elongated image comprises a plurality of parallel lines arranged at substantially +0° of said determined angle of astigmatism and said at least one fourth elongated image comprises a plurality of parallel lines arranged at substantially +90° of said determined angle of astigmatism, using said calibrated resolution acuity, such that in a calibrated position said user perceives said at least third first elongated image the same as said at least one fourth elongated image; - determining, by said device, a needed refraction based on a difference in thickness and/or blurriness between said at least one third elongated image at substantially +0° and said at least one fourth elongated image at substantially +90°. - determining, by said device, using feedback input received from a user, a calibrated rotation of a fifth elongated image (26, 37) displayed on said screen such that in a calibrated position said user perceives said displayed fifth elongated image (26, 37) substantially the most clear; - determining, by said device, an angle of astigmatism based on said calibrated rotation of said fifth elongated image; - calibrating, by said device, using feedback input received from said user, a resolution acuity of said user irrespective of said astigmatism by amending a thickness of at least one first elongated image comprising one or more lines displayed at substantially +45° of said determined angle of astigmatism and/or amending a thickness of at least one second elongated image comprising one or more lines displayed at substantially -45° of said determined angle of astigmatism such that in a calibrated position said user is just able to recognize said at least one first elongated image and/or said at least one second elongated image; - thickening and/or blurring, by said device, using feedback input received from said user, at least one third elongated image with respect to at least one fourth elongated image, wherein said at least one third elongated image comprises a plurality of parallel lines arranged at substantially +0° of said determined angle of astigmatism and said at least one fourth elongated image comprises a plurality of parallel lines arranged at substantially +90° of said determined angle of astigmatism, using said calibrated resolution acuity, such that in a calibrated position said user perceives said at least third first elongated image the same as said at least one fourth elongated image; - determining, by said device, a needed refraction based on a difference in thickness and/or blurriness between said at least one third elongated image at substantially +0° and said at least one fourth elongated image at substantially +90°.