Proceedings PaperA New Spline Algorithm For Computing And Developing Contact Lenses
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The methods of defining contact lenses used to date have presupposed a certain surface form: - that of a sphere, - that of a spheroid, - an appearance resembling these surfaces. The transition areas in the peripheral zones and the edge profiles were separately calculated and pieced together. This mathematical process resulted in a reduction of the free parameters. These difficulties are avoided by the spline algorithm presented herein. It is characterized by the following properties: 1. Every twice continuously differentiable surface can be represented. 2. Local influenceability without global effect. 3. EDP-friendly algorithm. ∫[f"(h)]2dh = min The parameterized form of the algorithm is of advantage for the definition of contact lens surfaces. Spherical surface elements can be very easily defined by modification of the process. This permits a reduction in the volume of data to be processed. An exact calculation of the system "eye - tear lens - contact lens" is performed as a practical example of the above. The deviation of the dioptric values of the decentred contact lens from the values in the centred position are graphically illustrated.