Multi-focal Lens Preferential Visual Span Design
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Solution Overview
Problem
Current treatments for presbyopia, such as glasses, contact lenses, and surgical procedures, often fail to provide effective multi-focal correction, leading to unsatisfactory vision outcomes, especially for advanced presbyopia cases, as they either cause blurriness in distant vision or require inconvenient head tilting for optimal focus.
Innovation Solution
The development of multi-focal ophthalmic lenses with a center optical zone for distant vision and a peripheral optical zone for near vision, featuring a preferential visual span (PVS) design, where the curvature of the peripheral zone is steeper than the center zone, creating distinct focal points to enhance clarity contrast and allow the brain to automatically select the appropriate image for reading, thereby improving presbyopia correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional multi-focal contact lenses are used, then both distant and near vision are provided simultaneously, but the clarity contrast between zones is insufficient leading to unsatisfactory vision outcomes
Solution Approach 1:
The patent applies local quality by creating distinct optical zones with different curvatures: a central zone with curvature C1 for distant vision and a peripheral zone with steeper curvature C2 for near vision. This localized differentiation of optical properties ensures that each zone provides optimized focusing for its specific function, thereby improving the clarity contrast between zones and overall vision correction effectiveness.
Solution Approach 2:
The contact lens is segmented into multiple distinct optical zones with different refractive powers. The central optical zone and peripheral optical zone are clearly demarcated, with each zone independently optimized for specific viewing distances. This segmentation allows the brain to selectively process images from appropriate zones, enhancing the overall multi-focal correction reliability.
2Reliability
If translating multi-focal contact lenses are used, then separate zones for far and near vision are provided, but head tilting is required to position the reading segment correctly
Solution Approach 1:
The patent transitions from the conventional translating design (requiring vertical head movement) to a preferential visual span design where the peripheral zone with steeper curvature naturally directs light to the parafovea region. This dimensional shift in optical design allows the user to maintain a natural head position while still achieving proper focus positioning, thereby improving ease of operation without sacrificing focus accuracy.
Solution Approach 2:
The optical design itself performs the positioning function that previously required user action (head tilting). The steeper peripheral curvature automatically directs light rays to the appropriate retinal region, making the system self-regulating and eliminating the need for user intervention to position the reading segment correctly.
3Ease of operation
If simultaneous vision multi-focal lenses are used, then convenience is improved for less presbyopic patients, but advanced presbyopia cases remain unsatisfactory
Solution Approach 1:
The patent modifies the curvature parameter across different zones of the lens, creating a progressive change from the central zone curvature C1 to the peripheral zone curvature C2. This parameter gradient is specifically optimized to provide sufficient add power for advanced presbyopia cases while maintaining natural viewing convenience, thereby improving both reliability and ease of operation simultaneously.
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
These lenses provide clearer near vision by creating a significant clarity contrast between far and near zones, allowing the brain to decode off-axis images from the parafovea or perifovea areas, effectively overcoming the limitations of traditional multi-focal devices and improving daily reading tasks without the need for head movement.
Implementation Method 1
The center optical zone focuses light that enters the front surface of the lens in a direction substantially parallel to the optical axis of the lens to create a first focal point within 2.5° of the optical axis
Implementation Method 2
the peripheral optical zone focuses light in a direction not parallel to the optical axis to create a second, non-overlapping focal point at between 2° and 10° with respect to the optical axis
Data Source
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AI summary
A multi-focal lens having a center optical zone for creating a first focal point within 2° of the optical axis and a peripheral optical zone located adjacent the center optical zone for creating a second focal point from 2° to 10° of the optical axis, the peripheral optical zone having a correction of at least 2 diopters more than the center optical zone.