Effect of rotation and translation on the expected benefit of an ideal method to correct the eye's higher-order aberrations

ideal correcting method, such as a customized contact lens, laser refractiv e surgery, or adaptive optics, that corrects higher-order aberrations as we ll as defocus and astigmatism could improve vision. The benefit achieved wi th this ideal method will be limited by decentration. To estimate the signi ficance of this potential limitation we studied the effect on image quality expected when an ideal correcting method translates or rotates with respec t to the eye's pupil. Actual wave aberrations were obtained from ten human eyes for a 7.3-mm pupil with a Shack-Hartmann sensor. We computed the resid ual aberrations that appear as a result of translation or rotation of an ot herwise ideal correction. The model is valid for adaptive optics, contact l enses, and phase plates, but it constitutes only a first approximation to t he laser refractive surgery case where tissue removal occurs. Calculations suggest that the typical decentrations will reduce only slightly the optica l benefits expected from an ideal correcting method. For typical decentrati ons the ideal correcting method offers a benefit in modulation 2-4 times hi gher (1.5-2 times in white light) than with a standard correction of defocu s and astigmatism We obtained analytical expressions that show the impact o f translation and rotation on individual Zernike terms. These calculations also reveal which aberrations are most beneficial to correct. We provided p ractical rules to implement a selective correction depending on the amount of decentration. An experimental study was performed with an aberrated arti ficial eve corrected with an adaptive optics system, validating the theoret ical predictions. The results in a keratoconic subject, also corrected with adaptive optics, showed that important benefits are obtained despite decen trations in highly aberrated eyes. (C) 2001 Optical Society of America.