Methods and apparatus ( 610 ) are disclosed for diagnosing vision and improving vision in a manner which does not interfere with the natural shape of the cornea or its orientation relative to the remainder of the eye, but which changes its surface curvature appropriately to achieve the required correction of vision. The focus of the cornea ( 14 ) is adjusted so that different regions focus substantially to the same axis and preferably to substantially the same point on the axis. This can be accomplished by shaping the cornea (e.g. through ablation) or by applying an appropriate contact lens or other optical lens. In either case, correcting the central portions of the cornea should have a more significant effect on correcting focus scatter than correcting the more outward portions.
