A method for determining at least one optical parameter of an eye of a person comprising displaying at least two sharp images on a retina of the eye of the person, the at least two images comprising a target and being carried by two light beams focused substantially in the plane of a pupil of the eye at at least two different positions, adapting a parameter of the target in each image based on feedback of the person relative to the change of the parameter of the target in the image, and determining the at least one optical parameter of the person's eye based on the adaption of the parameter of the target in each image.