Progressive Multifocal Contact Lens NURBS Profile Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multifocal contact lenses suffer from discontinuous power profiles and visual quality degradation due to discrete refractive power distribution, leading to discomfort and interference images, which existing methods struggle to address effectively.
Innovation Solution
A progressive multifocal contact lens with a Non-Uniform Rational B-spline (NURBS) profile on the front side surface, featuring a central zone, annular zone, and intermediate zone with progressive optical power adjustment, ensuring continuity and flexibility in power distribution between distance and near vision areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If discrete concentric optical rings are used for multifocal correction, then multiple vision zones (distance and near) are provided, but visual quality degrades due to discontinuous refractive power distribution
Solution Approach 1:
The patent applies parameter changes by transitioning from discrete refractive power zones to a continuous gradient of optical power. The refractive power is varied continuously across the lens surface using mathematical functions (conic sections, exponential functions, or polynomial series), creating a smooth progression from distance to near vision zones without abrupt transitions. This resolves the contradiction by maintaining multifocal adaptability while achieving continuous refractive power distribution.
Solution Approach 2:
The patent utilizes curved surface profiles defined by conic sections (ellipses, parabolas, hyperbolas) and other mathematical curves to create the refractive power distribution. These continuous curved surfaces replace the discrete concentric rings, providing smooth transitions between different vision zones while maintaining the multifocal correction capability.
2Adaptability or versatility
If conventional surface profiles are used to connect optical zones, then intermediate zones are added, but discontinuities remain causing interference images and reduced wearing comfort
Solution Approach 1:
The patent ensures continuous refractive power distribution across all optical zones by using mathematical functions that provide continuous derivatives. The transition between distance, intermediate, and near zones is achieved through smooth mathematical curves (conic sections, exponential functions, polynomial series) that eliminate abrupt changes in power or slope, thereby preventing interference images and visual discomfort while maintaining the beneficial intermediate zones.
3Manufacturing precision
If various conic curves are combined to reduce discontinuity, then geometric continuity is improved, but the design becomes complicated and center optical zone continuity is not always achieved
Solution Approach 1:
The patent employs universal mathematical frameworks (conic sections, exponential functions, polynomial series) that can describe various surface profiles using a single unified mathematical approach. These universal functions can be adjusted through parameters to achieve different optical zone configurations, intermediate zone widths, and power distributions, simplifying the design process while ensuring geometric continuity and center zone accuracy.
Data Source
AI summary
A progressive multifocal contact lens and producing method thereof are provided. The progressive multifocal contact lens includes a first optical region of a front optical surface and a second optical region of a back optical surface. The first optical region includes a center zone, an outer zone and an intermediate zone connected between the center zone and outer zone where the center zone and outer zone are selected from a distance vision power and a near vision power and the intermediate zone is configured to adjust the optical power of the distance vision power and the near vision power so that the optical power or add power of the first optical region on the front optical surface forms a normal cumulative distribution function.