Abstract: Techniques for lens design and evaluation involve configuring a rule comprising one of a “with the rule” and “against the rule”, configuring a cylinder comprising one of a “positive cylinder” and a “negative cylinder”, and utilizing the rule and the cylinder in one or both of a residual astigmatism metric algorithm and spherical equivalent metric algorithm to generate a discrete metric values each corresponding to ranges of residual refractive error.

Abstract: An apparatus for operation on a cornea by ablating with a laser beam for correcting ametropia; the apparatus comprising an input device utilized for inputting each data necessary for correction, a first correcting device for irradiating a laser beam for correcting myopic astigmatism, a second correcting device for irradiating a laser beam for correcting hyperopic astigmatism, a calculating device for calculating each correction-data based on the each inputted data in case of combining the first and second correcting means, and a control device for ablating the cornea by controlling the first and second correcting means based on results calculated by the calculating device.

Abstract: An apparatus for operation on a cornea by ablating with a laser beam for correcting ametropia; the apparatus comprising an input device utilized for inputting each data necessary for correction, a first correcting device for irradiating a laser beam for correcting myopic astigmatism, a second correcting device for irradiating a laser beam for correcting hyperopic astigmatism, a calculating device for calculating each correction-data based on the each inputted data in case of combining the first and second correcting means, and a control device for ablating the cornea by controlling the first and second correcting means based on results calculated by the calculating device.