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Mispositioning will result in oblique astigmatism and power error off-axis, similar to using an incorrect base curve, with the error dependent on the degree of mispositioning, lens power, and the p-value of the asphericity.
Semi-finished front aspherics should be fit following Martin's Rule for tilt, and free-form back aspheric/atoric designs should be fit according to instructions provided by the lens manufacturer, typically providing the pupil heights on a preadjusted eyeglass frame.
Workarounds include introducing thinning (yoked) prism , using spherical lenses with higher values for pantoscopic tilt, a different lens brand and/or material, a different frame that positions the lenses optimally, etc.
Hope this helps,
Robert MartellaroScience is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
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