This invention provides a method to design progressive contact lens to correct presbyopia. The refractive power gradually changes from either near or distance center to the opposite focal length in the periphery by using a continuous Non-Uniform Rational B-spline (NURBS) curve as a surface profile of the front optical surface. This invention allows a high degree of freedom of design the optical power distribution to adapt the visual requirement of a particular presbyopic patient. By using a free-form NURBS curve, this method not only provides a smooth and continuous front surface, but also satisfies various optical power distributions and additional power values taking account of pupil diameter. In addition, this method can be applied to manufacture the lens surface or lens mold with high accuracy for both soft and rigid contact lenses.
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