Progressive Addition Lens with Segmented Microlenses for Myopia Control
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Solution Overview
Problem
Current progressive addition lenses (PALs) are moderately effective in slowing down myopia progression initially but lose efficacy over time, and delivering simultaneous myopic defocus to the fovea is challenging without causing discomfort or eye strain, especially when combined with high negative mean power gradients around the near portion.
Innovation Solution
A progressive addition lens design with an annular array of microlenses where microlenses are excluded from areas below a specific vertical coordinate above the near reference point, ensuring the near portion remains clear for near vision tasks while maintaining the beneficial effect of negative aspherisation to reduce accommodative lag, and microlenses are strategically placed in other areas to provide myopic defocus without causing significant disruption to foveal vision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microlenses are applied across the entire surface of the progressive addition lens to provide myopic defocus, then the effectiveness in slowing myopia progression is improved, but comfort and acceptance deteriorate due to disruption of foveal vision and eye strain
Solution Approach 1:
The lens surface is segmented into distinct zones: a central clear aperture free of microlenses for comfortable foveal vision, and peripheral zones with microlenses for myopic defocus. This segmentation allows different regions to serve different functions, resolving the contradiction between effectiveness and comfort.
Solution Approach 2:
Different regions of the lens are given different optical properties: the central region has no microlenses to maintain clear foveal vision and comfort, while peripheral regions have microlenses to provide myopic defocus and slow progression. This local differentiation resolves the contradiction by applying microlenses only where they provide benefit without compromising central vision comfort.
2Ease of operation
If a clear aperture is provided in the near portion to maintain comfort, then comfort and acceptance are improved, but the area available for providing myopic defocus is reduced
Solution Approach 1:
The clear aperture is positioned vertically above the near reference point rather than covering the entire near portion, utilizing the vertical dimension to accommodate both the clear aperture for comfort and microlenses for myopic defocus in the same near portion area. This dimensional arrangement resolves the contradiction by optimizing spatial utilization.
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 enhances comfort and maintains the effectiveness of myopic defocus delivery, reducing accommodative lag and myopia progression while preventing eye strain, with large gradients in mean addition power around the near portion effectively slowing down axial elongation of the eyeball.
Implementation Method 1
A progressive addition lens with simultaneous myopic defocus providing microlenses
Implementation Method 2
a power variation surface providing at least a designated distance portion located in an upper section of the progressive addition lens adapted to distance vision, a designated near portion located in a lower section of the progressive addition lens
Data Source
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AI summary
A progressive addition lens with simultaneous myopic defocus providing microlenses, including a power variation surface is provided. The power variation surface (23) provides at least - a designated distance portion (1) located in an upper section of the progressive addition lens (19) adapted to distance vision, and a fitting cross (17); - a designated near portion (3) located in a lower section of the progressive addition lens, the near portion (3) including a near reference point (7) having a near dioptric power adapted to near vision; and - a designated intermediate corridor (9) extending between the designated distance portion (1) and the designated near portion (3); where a number of microlenses (13) is superimposed on a surface (23) of the progressive addition lens (19). Microlenses (13) are excluded from all areas of said surface (23) which are located below a notional line (15) that extends from nasal to temporal limits of the progressive addition lens (19) at a vertical coordinate (y) above the near reference point (7) where the vertical coordinate (y) lies at a distance above the near reference point (7) with the distance being in a range between 1.5 mm and 3 mm. In addition, a method of manufacturing a progressive addition lens (19) with simultaneous myopic defocus providing microlenses (13) is defined. The method includes the steps of: - Providing a progressive addition lens (19) with a power variation surface, where the power variation surface (23) provides at least a designated distance portion (1) in the upper section of the progressive lens, a designated near portion (3) in a lower section of the progressive addition lens (19), and a designated intermediate corridor (9) extending between the designated distance portion (1) and the designated near portion (3). The distance portion (1) includes the distance reference point (5) and the fitting cross (17). The near portion (3) includes a near reference point (7). - Superimposing a number of microlenses (13) on a surface (23) of the progressive addition lens (19), where superimposition of microlenses (13) is excluded from all areas of said surface (23) which are located below a notional line (15) that extends from nasal to temporal limits of the progressive addition lens (19) at a vertical coordinate (y) above the near reference point (7) where the vertical coordinate (y) lies at a distance above the near reference point (7) with the distance being in a range between 1.5 mm and 3 mm.