Multiplexing Prism Eliminates Apical Scotoma in Low Vision Devices
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Solution Overview
Problem
Conventional prisms used to shift views in low vision conditions create an apical scotoma, a blind spot that limits the field of view due to their refractive properties, which is equal in extent to the prism's power, thereby reducing the effective visual field expansion.
Innovation Solution
A multiplexing prism design that combines prismatic elements with non-prismatic portions, allowing light to pass unshifted, thereby reducing or eliminating the apical scotoma by overlaying shifted and unshifted views, using an array of prisms that bend light and flat portions that do not shift light, which can be oriented in various configurations to enhance the field of view without blocking areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional prism is used to shift light, then the field of view is expanded, but an apical scotoma (blind spot) is created that reduces the effective visual field
Solution Approach 1:
The optical element is divided into multiple discrete prismatic portions arranged in an array, where each portion shifts light by a specific amount. This segmentation allows different regions of the visual field to be redirected to different locations on the retina, expanding the overall field of view while maintaining visibility through non-prismatic regions.
Solution Approach 2:
Different portions of the optical element have different optical properties: some regions contain prismatic elements that shift light, while other regions are non-prismatic and allow direct light transmission. This local differentiation enables simultaneous field expansion through prismatic regions and maintenance of central vision through non-prismatic regions, eliminating the apical scotoma problem.
2Volume of moving object
If a Fresnel prism is used to reduce bulk, then the device becomes thinner, but the apical scotoma problem persists
Solution Approach 1:
The Fresnel prism structure is segmented into discrete prismatic portions arranged in an array rather than a continuous structure. This allows the adoption of a multiplexing configuration where prismatic and non-prismatic regions are interleaved, reducing bulk while eliminating the apical scotoma through the non-prismatic portions.
Solution Approach 2:
The invention merges prismatic elements with non-prismatic portions in a multiplexing arrangement, combining the field-shifting capability of prisms with the clear view transmission of non-prismatic regions. This hybrid structure maintains the thin profile of Fresnel prisms while eliminating their primary drawback of creating apical scotoma.
3Area of stationary object
If multiple prisms are used to expand field of view, then peripheral awareness is improved, but complexity of the device increases
Solution Approach 1:
The visual field expansion is achieved through segmentation of the optical element into multiple discrete prismatic portions, each handling a specific directional shift. This modular approach allows systematic arrangement of prisms with different orientations and powers to address various visual field defects while maintaining manageable device complexity.
Solution Approach 2:
The array of prismatic portions serves multiple functions simultaneously: expanding the visual field in multiple directions, redirecting light from different visual field regions to appropriate retinal locations, and working in conjunction with non-prismatic portions to eliminate apical scotoma. This multi-functionality reduces the need for separate optical elements for different purposes.
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 multiplexing prism effectively expands the visual field without introducing an apical scotoma, providing enhanced peripheral awareness and mobility aids for patients with visual field loss conditions by simultaneously shifting and superimposing views, maintaining clear central vision and reducing brightness variations.
Implementation Method 1
A prism is a transparent optical element with flat, polished surfaces that refract light
Implementation Method 2
a plurality of portions configured to pass light unshifted through the apparatus
Data Source
AI summary
In some example implementations, there is provided an apparatus. The apparatus may include a plurality of prism portions configured to shift light passing through the apparatus including the plurality of prisms portions, and a plurality of portions configured to pass light unshifted through the apparatus, wherein the apparatus combines the shifted light and the unshifted light passing through the apparatus. Related apparatus are also disclosed.