The invention relates to a method for determining the visual acuity of an eye and a respective apparatus. The method comprises the steps of: providing the wavefront information of the eye, generating a point spread function based on the wavefront information of the eye, said point spread function representing a specific intensity distribution for a corresponding pupil size. After comparing the intensities of the point spread function with a selectable intensity level of intensity, those parts of the point spread function having an intensity being larger than the selectable intensity level are determined as a relevant part of the point spread function.