Contact Lens Central Optically Inactive Zone Depth of Field
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Solution Overview
Problem
Existing contact lenses for correcting visual defects such as hypermetropia, myopia, and astigmatism are complex to produce and often result in unsatisfactory vision correction, with some designs causing perceptible shadow zones that compromise vision.
Innovation Solution
A contact lens with an optically inactive central region, featuring microgrooves or variable dioptric power, which increases the depth of field without creating noticeable shadow zones, allowing for effective long- and short-distance vision correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an optically inactive zone is introduced to correct visual defects, then depth of field is improved, but shadow zones become perceptible to the user
Solution Approach 1:
The patent applies local quality by creating a central region with specifically engineered microgrooves that have different optical properties than the surrounding lens. This localized structural modification allows the central region to increase depth of field while the peripheral optical zones remain clear and free of shadow zones, resolving the contradiction between improved depth of field and avoidance of perceptible shadows.
Solution Approach 2:
The patent changes physical parameters by introducing microgrooves with specific geometric characteristics (depth, width, spacing) in the central region. These parameter modifications alter the optical path and light scattering properties locally, increasing depth of field without creating the dense shadow zones that would compromise overall vision.
2Adaptability or versatility
If multifocal zones with differentiated dioptric powers are implemented, then vision correction for multiple distances is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the lens into distinct functional zones: a central region with microgrooves for depth of field enhancement, an intermediate region for transition, and peripheral optical zones for distance correction. This segmentation allows each zone to be optimized independently while simplifying the overall manufacturing process compared to complex continuous multifocal designs.
Solution Approach 2:
Instead of using traditional multifocal approaches that vary dioptric power continuously or in complex patterns, the patent inverts the approach by using a central region with reduced optical activity (microgrooves) surrounded by clear optical zones. This inverted structure achieves multifocal benefits while dramatically simplifying manufacturing.
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 contact lens provides improved visual performance by reducing the circle of confusion and enhancing depth of field, enabling effective correction of a wide range of visual defects, including hypermetropia, myopia, and presbyopia, without perceptible shadow zones.
Implementation Method 1
images are formed on the retina only by the light passing through the portion of lens outside the optically inactive zone, with a consequent reduction of the circle of confusion, since the light passing through the optically inactive zone, which surrounds the optical axis over a limited diameter, does not contribute to the formation of any distinguishable image
Implementation Method 2
the dioptric power of the lens varies according to the distance from the optical axis of the lens... zones with differentiated dioptric powers according to graduations that may assume quite complex profiles
Data Source
Figure 1~3
AI summary
A contact lens (1) comprises an optical zone (5) extending with a first diameter (A) about an optical axis (X) of the lens, and is provided with a first dioptric power and a central region (6), extending about the optical axis (X) with a second diameter (B), smaller than the first diameter, inside which is provided an optically inactive zone (7) with a diameter smaller than 0.5 mm.