Multifocal Contact Lens Aspheric Profile for Presbyopia
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Solution Overview
Problem
Multifocal contact lenses often compromise distance or near visual acuity and cause visual discomfort, especially for presbyopic subjects requiring medium or high Add powers, due to secondary images or 'ghost' images, and the large number of lens options complicates the fitting process for eye care practitioners and manufacturers.
Innovation Solution
Designing multifocal contact lenses with an aspheric power profile in the optic zone that balances distance and near vision refractive powers, where the dominant eye is monocularly optimally corrected for distance vision and the non-dominant eye is monocularly over-corrected for distance vision, while binocularly under-corrected for Add power, to enhance binocular visual acuity without additional visual compromise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multifocal contact lenses with defined zones and narrow transitions are used, then near vision correction is improved, but ghosting and visual discomfort increase
Solution Approach 1:
The patent employs aspheric optical surfaces with continuous curvature changes instead of sharp transitions between zones. The front surface aspheric design creates a smooth gradient from distance to near power regions, eliminating the abrupt boundaries that cause ghosting while maintaining effective near vision correction.
Solution Approach 2:
The patent varies the refractive index and optical power parameters continuously across the lens surface rather than using discrete zones. By adjusting the aspheric coefficient and power distribution gradients, the lens achieves seamless transition between distance and near focal points, reducing optical interference and ghosting effects.
2Adaptability or versatility
If multiple lens options with different sphere and Add powers are provided, then adaptability to different presbyopic subjects is improved, but device complexity and inventory requirements increase
Solution Approach 1:
The patent creates a universal lens platform with adjustable aspheric parameters that can accommodate multiple presbyopic corrections. By varying the sphere power and Add power within a single aspheric design framework, the system provides customized correction for different patients without requiring entirely different lens designs, reducing inventory complexity.
Solution Approach 2:
The patent uses parameter-based customization where sphere power, Add power, and aspheric coefficients can be adjusted to create different prescription variants from a single base design. This approach allows manufacturers to meet diverse patient needs while maintaining a streamlined production system with fewer unique lens models to inventory.
3Adaptability or versatility
If distinct optical zones with alternating distance and near refractive powers are used, then multifocal vision is improved, but contrast loss and visual compromise increase
Solution Approach 1:
The patent uses continuous aspheric curvature variations to create smooth optical power transitions instead of distinct alternating zones. This eliminates sharp boundaries between distance and near power regions, reducing light scattering and contrast loss while maintaining effective multifocal vision across different distances.
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 solution provides improved binocular visual acuity for presbyopic subjects with medium or high Add powers by minimizing visual disturbances like ghosting and contrast loss, while simplifying the fitting process and reducing inventory for manufacturers.
Implementation Method 1
The optic zone has an aspheric power profile extending from the optic zone center towards the optic zone perimeter and provides a near vision refractive power and a distance vision refractive power
Data Source
Figure 1A~1F
Figure 2A~2B
Figure 3~4
AI summary
Multifocal contact lenses and methods and uses are described. The multifocal contact lenses include an optic zone. The optic zone has an aspheric power profile that provides a near vision refractive power and a distance vision refractive power, and provides an Add power that corresponds to the difference between the near vision refractive power and the distance vision refractive power. The multifocal contact lenses can improve binocular vision of presbyopic subjects by being prescribed such that the non-dominant eye contact lens is over-corrected for distance vision, and both multifocal contact lenses are under-corrected for the Add power requirement of the subject. Batches and sets of multifocal contact lenses are also described.