Progressive Ophthalmic Lens Addition Distribution for Magnification Stability
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Solution Overview
Problem
Progressive ophthalmic lenses often cause discomfort due to variations in magnification when the wearer changes direction of gaze, leading to a sensation of pitching or balance disturbance, particularly when head movements are more pronounced.
Innovation Solution
The method involves selecting the addition values for the front and rear faces of the lens to minimize magnification differences between near and far vision zones, based on the wearer's eye and head movement patterns, thereby personalizing the lens design to reduce discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the addition values of the front and rear faces are optimized to reduce residual astigmatism, then the optical quality is improved, but the magnification variation between near and far vision zones increases, causing pitching sensation
Solution Approach 1:
The patent applies parameter changes by adjusting the addition values of the front and rear faces based on the wearer's eye and head movement characteristics. Different addition distributions are selected to optimize both optical quality and magnification stability for different wearer types, resolving the contradiction between reducing astigmatism and controlling magnification variation.
2Area of stationary object
If the lens is designed with wide vision zones and high power gradients for eye-movers, then the visual coverage is improved, but the magnification variation increases causing discomfort
Solution Approach 1:
The patent applies local quality by tailoring the lens design parameters specifically for different wearer types. For eye-movers, the lens is designed with specific addition distributions that balance wide vision coverage with controlled magnification variation, while head-movers receive a different optimization. This localized optimization resolves the contradiction between vision zone width and magnification stability.
3Object-affected harmful factors
If the addition distribution is optimized for head-movers with low power gradients, then the magnification stability is improved, but the vision zone width decreases
Solution Approach 1:
The patent applies local quality by creating distinct lens designs for different wearer types. Head-movers receive lenses with lower power gradients and specific addition distributions that stabilize magnification, while accepting narrower effective vision zones as a trade-off. This localized optimization resolves the contradiction between magnification stability and vision zone width for this specific user group.
Data Source
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AI summary
A method for producing an ophthalmic glass (1) intended for an identified wearer of spectacles comprises distribution of an optical power addition between an anterior face (SANT) and a posterior face (SPOST) of said glass. Said distribution of the addition is done in such a way as to modify an optical characteristic as a function of relative amplitudes of eye and head movements of the wearer. Superior comfort of the glass in use is thus obtained. The optical characteristic which is considered may be, in particular, a variation of magnification procured by the glass between far and near vision conditions. An improvement of the invention is to also modify a design of the progressive glass as a function of the amplitudes of the eye and head movements of the wearer, using only a single semifinished glass model of fixed design for each addition value of the anterior face.