Spiral Multifocal Ophthalmic Lens for Stable Near-Distance Focus
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Solution Overview
Problem
Multifocal ophthalmic lenses with concentric rings or aspheric power profiles experience variations in the ratio of near to distance focusing due to pupil dilation and constriction, leading to distraction and loss of vision, particularly in changing light conditions.
Innovation Solution
A multifocal ophthalmic lens with a spiral surface power map that varies periodically both radially and angularly, maintaining a constant ratio of near to distance focusing across varying pupil sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If concentric rings or aspheric power profiles are used in multifocal ophthalmic lenses, then near and distance focusing are provided, but the ratio of near to distance focusing varies with pupil size causing distraction and vision loss
Solution Approach 1:
The patent transitions from conventional two-dimensional concentric ring or radial aspheric power profiles to a three-dimensional spiral power profile that extends in both radial and angular dimensions. This spiral configuration allows the lens to maintain a constant ratio of near to distance focusing across varying pupil sizes by distributing optical zones along a spiral path rather than concentric circles, thereby resolving the stability issue while preserving multifocal capability.
2Illumination intensity
If the pupil constricts in bright conditions, then light intake is limited, but the quantity of one of near or distance focussing is reduced causing loss of multifocal vision
Solution Approach 1:
By arranging optical zones along a spiral path rather than concentric circles, the lens ensures that both near and distance focusing zones remain positioned within the entrance pupil across the full range of pupil diameters. The spiral configuration guarantees that as the pupil constricts in bright conditions, the relative proportions of near and distance zones remain constant, preventing the complete loss of multifocal vision that occurs with conventional designs.
3Ease of operation
If alternating concentric rings are used, then near and distance vision are provided, but the number of rings across the entrance pupil varies with pupil size causing variation in lens power ratio
Solution Approach 1:
The patent replaces the conventional two-dimensional concentric ring arrangement with a three-dimensional spiral power profile that incorporates both radial and angular variations. This spiral configuration maintains a constant ratio of near to distance focusing across varying pupil sizes, simplifying the effective power distribution while preserving the multifocal vision correction capability.
Data Source
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AI summary
A multifocal ophthalmic lens has a surface that varies across at least a portion of the lens to form a surface power map. The surface power map comprises a spiral, with a power that varies substantially periodically both radially outwards from and angularly about an optical axis of the lens. A period of the radial variation is greater than 100 microns and a period of the angular variation is greater than 6 degrees. Methods of making and using the multifocal ophthalmic lens are also described.