Abstract
We present a practical method for reconstructing the optical system of the human eye from off-axis wavefront measurements. A retinal beacon formed at different locations on the retina allows probing the optical structure of the eye by the outgoing beams that exit the eye through the dilated pupil. A Shack-Hartmann aberrometer measures the amount of wave aberrations in each beam at the exit pupil plane. Wavefront data obtained at different oblique directions is used for tomographic reconstruction by optimizing a generic eye model with reverse ray-tracing. The multi-configuration system is constructed by tracing pre-aberrated beams backwards from each direction through the exit pupil into the optical system of the aberrometer followed by the generic eye model. Matching all wave aberrations measured at each field point is equivalent to minimizing the size of the beacon spots on the retina. The main benefit of having a personalized eye model is the ability to identify the origin of the ocular aberrations and to find the optimal way for their correction.
Highlights
The imaging quality of any optical system can be characterized in terms of wave aberrations, which are usually expanded into orthonormal Zernike functions defined over a circular aperture [1]
Symmetric optical systems exhibit symmetric distribution of field aberrations that can be characterized in annular zones of the field [4], whereas for the optical systems that lack any type of symmetry, e.g. the human eye, the characterization of image quality involves larger number of field points
We have presented a method of reconstructing the optical system of the eye from wavefront measurements by using reverse ray tracing
Summary
The imaging quality of any optical system can be characterized in terms of wave aberrations, which are usually expanded into orthonormal Zernike functions defined over a circular aperture [1]. Aberrations vary across the field, one needs to use different sets of Zernike coefficients to describe each isoplanatic patch of the field In astronomy, the latter is usually defined as an area of the field where the variation of the rootmean-square (RMS) wavefront error between any two points does not exceed 1 rad [3]. The human eye is a good example of the optical system with prior knowledge on its typical structure, which is represented by age-dependent generic eye models [5] The latter can be optimized to fit the measured wave aberrations at all reference points in the field. The probing beam created from a reference source on the retina exits the eye and traverses the aberrometer sensing arm until it reaches the exit pupil, where the lenslet array is replaced by an imaginary phase plate. The general strategy for optimizing the optical parameter in the generic eye model with a gradient index (GRIN) lens is presented
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