Moiré pattern movement compensation and quadrature averaging phase retrieval from time series of speckled arbitrary phase shift interferograms for automatic computation of fundus pulsation curve of the human eye.

PURPOSE: the method described here allows for automatic calculation of the fundus pulse from interferometric measurements. METHOD: a low intensity laser beam is coupled into the eye. Two strong reflections, one of the cornea and one of the retina, interfere on a high-speed complementary metal-oxide-semiconductor camera chip. After eye movement compensation, a speckle-free phase of the interferograms is calculated from a series of interference fringes. Then, the fundus pulsation is calculated from the phase shift between two consecutive interferograms. PROBLEMS: occurring speckle perturbs the fringe images, and therefore, classical geometrical movement compensation algorithms do not work with sufficient accuracy. The movement compensation algorithm needs to work without prior knowledge of the phase. RESULTS: the proposed algorithms yield the fundus pulse from speckled interferograms, overcoming the above mentioned problems.

In vitro strehl ratios with spherical, aberration-free, average, and customized spherical aberration-correcting intraocular lenses.

PURPOSE: To determine in vitro image qualities of artificial eyes achieved with spherical, aberration-free, average spherical aberration-correcting, and customized spherical aberration-correcting IOLs in centered, decentered, and tilted positions. METHODS: The in vitro performance of these IOL models was determined by optical bench measurements. The experimental setup included a laser light source controlled by aperture stops that corresponded to 3- and 5-mm pupil apertures, an artificial eye with three alternative corneal models exhibiting low, intermediate, and high spherical aberration (SA), IOLs mounted to an immersed IOL holder that could be moved laterally and tilted, and a charge-coupled device camera and software to determine three-dimensional point spread function (PSF), modulation transfer function, and Strehl ratio. RESULTS: Differences among the various lens models turned out to be low for a 3-mm pupil. For a pupil aperture of 5 mm, customized IOLs showed the best results for perfect lens positioning. With ongoing decentration and tilt, customized IOLs rapidly lost their advantages, particularly in corneas with high SA and IOLs of high diopters. Spherical IOLs were always inferior to aberration-free IOLs. CONCLUSIONS: Reasonably well-centered aberration-correcting IOLs may provide considerably better image quality than conventional spherical IOLs. In the presence of significant postoperative decentration and tilt of the IOL, aberration-free IOLs are the safest option among the various intraocular lens designs.