Progressive Addition Lens Design for Near-Task Visual Comfort
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Solution Overview
Problem
Current ophthalmic progressive addition lenses for myopic or emmetropic presbyopic wearers do not adequately enhance visual comfort, especially for tasks at distances of 70 cm and less, due to limitations in refractive power distribution and astigmatism management.
Innovation Solution
A method for designing ophthalmic progressive addition lenses that calculates specific refractive power repartition, astigmatism distribution, and meridian lines to meet criteria such as A1/A2 ≥ 0.50 and CRITER ≤ 0.7, optimizing visual comfort by reducing peripheral aberration peaks and improving acuity at closer distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional progressive addition lenses are used for myopic or emmetropic presbyopic wearers, then far vision correction is provided, but visual comfort for tasks at distances of 70 cm and less is insufficient
Solution Approach 1:
The patent applies local quality by creating zone-specific refractive power distributions within the lens. It defines specific zones (first zone with lower refractive power, second zone with higher refractive power) and controls the transition between them using a transition curve. This allows different regions of the lens to provide appropriate correction for different viewing distances, thereby improving visual comfort for near tasks while maintaining far vision correction.
Solution Approach 2:
The patent employs parameter changes by systematically varying the refractive power across different zones of the lens. It uses specific parameters including refractive power values (P1, P2), transition curve characteristics (k1, k2), and zone boundaries (r1, r2) to create a progressive addition lens that optimizes visual comfort. The method also controls astigmatism parameters (axis and magnitude) within each zone to achieve the desired optical performance.
2Object-affected harmful factors
If conventional progressive addition lenses are used, then presbyopia correction is provided, but peripheral aberration peaks are not sufficiently reduced
Solution Approach 1:
The patent applies local quality by creating zone-specific refractive power distributions within the lens. It defines specific zones (first zone with lower refractive power, second zone with higher refractive power) and controls the transition between them using a transition curve. This allows different regions of the lens to provide appropriate correction for different viewing distances, thereby improving visual comfort for near tasks while maintaining far vision correction.
Solution Approach 2:
The patent employs parameter changes by systematically varying the refractive power across different zones of the lens. It uses specific parameters including refractive power values (P1, P2), transition curve characteristics (k1, k2), and zone boundaries (r1, r2) to create a progressive addition lens that optimizes visual comfort. The method also controls astigmatism parameters (axis and magnitude) within each zone to achieve the desired optical performance.
3Measurement precision
If conventional progressive addition lenses are used, then addition power is provided, but acuity at close distances is not sufficiently improved
Solution Approach 1:
The patent applies local quality by creating zone-specific refractive power distributions within the lens. It defines specific zones (first zone with lower refractive power, second zone with higher refractive power) and controls the transition between them using a transition curve. This allows different regions of the lens to provide appropriate correction for different viewing distances, thereby improving visual comfort for near tasks while maintaining far vision correction.
Solution Approach 2:
The patent employs parameter changes by systematically varying the refractive power across different zones of the lens. It uses specific parameters including refractive power values (P1, P2), transition curve characteristics (k1, k2), and zone boundaries (r1, r2) to create a progressive addition lens that optimizes visual comfort. The method also controls astigmatism parameters (axis and magnitude) within each zone to achieve the desired optical performance.
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 method enhances visual comfort and acuity for myopic or emmetropic presbyopic wearers by optimizing refractive power distribution and astigmatism management, particularly at distances of 70 cm and less, thereby improving overall visual performance.
Implementation Method 1
a lens criterion, A1/A2, fulfils following requirement: where: A1 = α100% - α85% ; A2 = α100% - α60% ; α100% being the lowering angle corresponding to the minimum positive α angle between: the lowering angle where 100% of the prescribed addition is perceived by the wearer on the meridian line, the lowering angle where the mean refractive power on the meridian line is maximum, PPO max (α ML , β ML )
Data Source
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AI summary
An ophthalmic progressive addition lens for a myopic or emmetropic presbyopic wearer which has a prescribed far vision mean refractive power a non nil prescribed addition, ADDp, said lens having a far vision reference point, a mean refractive power, PPO(α, β), a module of resulting astigmatism, ASR(α, β), a meridian line, ML(α, β), said (α, β) functions being determined in as-worn conditions of the lens by the wearer for gaze directions (α, β) joining the center of rotation of the eye, CRE, and the lens, where α is a lowering angle in degree and β is an azimuth angle in degree, and wherein a lens criterion, A1/A2, fulfils following requirement: A1/A2 ≥ 0.50, where: A1 = α100% - α85%; A2 = α100% - α60%.