Dynamic retinal image reconstruction of the human eye

Human visual performance is usually measured by conventional techniques (eg. letter charts), which cannot provide complete information of what a person actually sees in complex scenes. This paper considers reconstruction of the retinal image for real-world scenes based on the monochromatic aberrations of the human eye. Such aberrations can be evaluated by using an aberroscope or a Hartmann-Shack wavefiont sensor. In particular, we develop methodology for dynamic image reconstruction, in which we allow the aberrations to vary in time. We then apply this methodology to subjects with significant amount of higher-order monochromatic aberrations. I INTRODUCTION Most real-world scenes that we see can be decomposed into constituent spatial fiequencies, contrast and the orientation of spatial detail. If the aberrations of the eye are known, it is possible to mathematically model the retinal image of the eye in question by combining the object (scene) properties with the optical characteristics of the eye. The optical component of the human vision system can be assumed as a linear optical system with an object at the entrance pupil and an image at the retina acting as an input and output of the system, respectively. Within such a system, linear system theory and Fourier theory [I] can be applied. The term accommodation in optometry is equivalent to change of focus in engineering. Another term that is frequently used in this paper is the wuvefiont error. It is defined as a scaled difference between the optical path lengths of a ray under consideration and a chief ray [2]. The scaling factor is the wavelength, usually h = 555nm. Geometric optics can be linked with the linear system theory by the concept of the complex pupil function (CPF) where A@, 9 is the amplitude transmittance pupil function, W@,9 is the wavefront error pupil function, often referred to as the wavefront aberration, (p,@ are pupil polar coordinates, with p being the normalised distance from the origin (line-of-sight), and &he angle. Work has been done to relate ocular or corneal aberrations to image quality. However, only modelling of aberrations rather than real measurements has been considered. Also, all analysis was performed along one particular meridian and no application had been attempted on a real complex scene. When a scene is static and accommodation is fixed, the wavefiont error of the human eye can be expanded into a polynomial series [2]. In the series, some lower order terms are used to …