Calculation of post-lens pressure profile for contact lens
AssigneesVision CRC Limited, Novartis AG
InventorGeoffrey Brent
Life of this patent
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Abstract
A system for facilitating contact lens design comprises an input unit for input of design parameters, and a processing unit for calculating a post-lens pressure profile based on the design parameters. The processing unit is arranged, in use, to perform a finite model calculation allowing for large deflection and non-linear geometry effects in the deformation of a model lens shape. Preferably the finite element model calculation utilizes solid elements of modelling the lens shape. A contact comprising a high Young's modulus material such as silicone hydrogel can be designed to have a maximum corneal or limbal post-lens pressure valve of less than 250 Pa.
Claims16
A system for facilitating contact lens design before manufacture, the system comprising:
- an input unit configured for input of model design parameters based solely on at least one from a group consisting of model designs and model measurements, and
- a processing unit for calculating a post-lens pressure profile based on the model design parameters, the post-lens pressure profile is calculated with respect to a model representation of a standard eye, wherein the post-lens pressure profile is calculated by applying a frictionless sliding contact approximation between the model contact lens and the model eye, wherein the frictionless sliding contact approximation comprises a small distance separation between the lens and the eye;
- wherein the processing unit is arranged, in use, to perform a finite element model calculation allowing for large deflection/non-linear geometry effects in the deformation of a model lens shape, wherein the finite element model calculation utilizes solid elements for modeling the lens shape,
- wherein the model lens and eye parameters are defined by applying a pressure evenly across the contact lens surface, examining pressure peaks identified from the pressure application, evaluating continuity of the pressure peaks and repeating the process if not acceptably continuous, and analyzing the height of the pressure peaks.
A method of calculating a post-lens pressure profile based on model design parameters based solely on at least one from a group consisting of model designs and model measurements, comprising performing a finite element model calculation allowing for large deflection/non-linear geometry effects in the deformation of a model lens shape, wherein the finite element model calculation utilizes solid elements for modeling the lens shape, wherein the post-lens pressure profile is calculated before manufacture with respect to a model representation of a standard eye, wherein the post-lens pressure profile is calculated by applying a frictionless sliding contact approximation between the model contact lens and the model eye, wherein the frictionless sliding contact approximation comprises a small distance separation between the lens and the eye, wherein the model lens and eye parameters are defined by applying a pressure evenly across the contact lens surface, examining pressure peaks identified from the pressure application, evaluating continuity of the pressure peaks and repeating the process if not acceptably continuous, and analyzing the height of the pressure peaks.
Dependencies are inferred from the claim text.