The invention claimed is:
1. A method for designing, by means of a computer, at least one surface of a lens for a user, the method comprising steps of:
(i) obtaining a parameter of the user at a reference fitting position where a reference fitting point of the lens is located on a reference line of sight of an eye of the user, the reference line of sight being substantially horizontal;
(ii) determining a user specific fitting position where a user specific fitting point is located, the user specific fitting position being vertically shifted from the reference fitting position at least partly on the basis of an expected usage of the lens by the user, in which the user specific fitting position is located at a position vertically shifted from the position of the reference fitting point of the lens in the reference fitting position;
(iii) obtaining displacement information on an amount of vertical displacement between a height of the user specific fitting position and a height of the reference fitting position; and
(iv) designing the at least one surface of the lens at least partly on the basis of prescription information and on the basis of a modified parameter of the user which is calculated from the parameter of the user based on the amount of the vertical displacement, wherein
the parameter of the user includes a relative placement between the lens and a face of the user, or between a frame and the eye.
2. The method according to claim 1 , wherein said designing of said at least one surface of the lens further comprises calculating a design of said at least one surface at least partly on the basis of design characteristic information representing information corresponding to a design having predetermined characteristics relative to said reference fitting position.
3. The method according to claim 1 , further comprising a step of obtaining a physical lens including at least one surface corresponding to the designed at least one surface, and fitting the physical lens at a position corresponding to the reference fitting position.
4. The method according to claim 1 , further comprising a step of sending said displacement information from a displacement obtaining device to a lens surface design device, wherein
said designing of the at least one surface of the lens comprises causing said lens surface design device to design said at least one surface at least partly on the basis of said displacement information.
5. A non-transitory computer readable medium storing thereon a computer program for designing at least one surface of a lens for a user, the computer program comprising instructions configured to execute, when the computer program is executed on a computer, all of the steps of claim 1 .
6. A lens designed according to the method of claim 1 .
7. The method according to claim 1 , wherein the designing of the at least one surface is further on the basis of at least one of a Frame Corneal Distance (FCD), a Wearers Pantoscopic Angle (WPA), and a Cornea Vertex Distance (CVD).
8. The method according to claim 2 , wherein the design characteristic information comprises one of a clear design, a soft design, and a far vision design.
