Eccentric photorefraction (EPR) is a technique for measuring the refractive state of the human eye. Up to now, the crescent formation and light-intensity distribution of the pupil image in eccentric photorefractometer are all analyzed by geometrical optical theory, and the diffraction effects are neglected. For improving the accurateness of theoretic analysis, a space variable method based on wave optics is presented. The creation of crescent is proved to be a space variable process, and the pupil image and the corresponding intensity distribution on the meridian for different myopic diopters are simulated by computer. The simulated results are compared with those obtained by geometrical optical theory and show that the method is more accurate.