Multifocal Ophthalmic Lens Progressive Power Distribution
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Solution Overview
Problem
Multifocal intraocular lenses with three-zone optical designs face issues with shallow depth of focus for near vision, leading to difficulties in changing visual points at different near distances and increased occurrences of halo and glare symptoms, as well as image jump phenomena, due to power discontinuities and inadequate intermediate vision acuity.
Innovation Solution
A multifocal ophthalmic lens design with progressively varying power distribution in far and near zones, featuring stepwise power differences at zone boundaries, deepens the depth of focus for both far and near vision, reduces halo and glare symptoms, and minimizes image jump by optimizing power distribution and considering corneal spherical aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a three-zone optical design with constant power zones is used, then the lens structure is simple and easy to manufacture, but the depth of focus is shallow and visual comfort is reduced
Solution Approach 1:
The patent changes the power distribution parameter from constant to progressive variation within zones. By making power vary progressively from center to periphery within each zone, the depth of focus is extended while maintaining the three-zone structural simplicity for manufacturing.
Solution Approach 2:
The patent applies different power distribution characteristics to different regions within zones. Each zone has progressive power variation tailored to its specific function, with the degree and pattern of variation optimized for local optical requirements while maintaining overall structural simplicity.
2Device complexity
If power distribution is uniform across zones, then the lens design is simple, but halo and glare symptoms increase due to power discontinuities
Solution Approach 1:
The patent modifies the power distribution parameter to vary progressively within zones rather than remaining uniform. This progressive variation reduces abrupt power discontinuities at zone boundaries, thereby minimizing halo and glare symptoms while keeping the design relatively simple.
Solution Approach 2:
The patent anticipates and cushions the abrupt transitions at zone boundaries by implementing progressive power variation that smoothly connects adjacent zones. This beforehand cushioning prevents the sudden power changes that cause halo and glare effects.
3Ease of manufacture
If abrupt power changes occur at zone boundaries, then the lens manufacturing is easier, but image jump phenomena increase
Solution Approach 1:
The patent changes the power distribution from abrupt step changes to progressive variation across zone boundaries. This gradual transition maintains manufacturing feasibility while eliminating image jump phenomena that result from sudden power discontinuities.
Solution Approach 2:
The patent cushions the power transitions at zone boundaries through progressive power variation, preventing abrupt changes that would cause image jumps. This beforehand cushioning ensures smooth optical transitions while maintaining manufacturing simplicity.
4Measurement precision
If the near zone has high addition power, then near vision acuity is improved, but the clearly seen range at near distance is limited
Solution Approach 1:
The patent changes the power distribution in the near zone from constant to progressive variation. By gradually varying power from center to periphery, the lens extends the depth of focus for near vision, allowing a broader clearly seen range while maintaining high near vision acuity through the peak addition power region.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design extends the range of clear vision for both far and near distances, improves comfort, and reduces the likelihood of halo and glare symptoms, while maintaining clear image quality and minimizing image jump phenomena.
Implementation Method 1
When seeing an object at far distance in a bright environment, pupil of eye contracts. In this lighting condition, almost all light is refracted on retina through the center zone (zone for correcting far vision) of the multifocal intraocular lens
Data Source
Figure 1
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Figure 4(A)~4(B)
AI summary
A multifocal ophthalmic lens, including: a far zone for correcting a far vision; and a near zone for correcting a near vision, arranged concentrically in an optical region of the lens, wherein a power distribution is set to vary progressively in radial direction of the far zone and the near zone; power is altered discontinuously to have a stepwise power difference at a boundary between the far zone and the near zone, the value of the power difference at the boundary between the far zone and the near zone is not greater than a maximum value of an intermediate power for correcting an intermediate vision.