Ocular Rotation Centre Determination Using Visual Axis Alignment
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Solution Overview
Problem
Current methods cannot precisely determine the centre of ocular rotation with respect to a lens, leading to inaccuracies in lens design and adaptation, which results in geometric aberrations such as oblique astigmatism and power error.
Innovation Solution
A method involving establishing fixation points, measuring angles, aligning references with the visual axis, and calculating the position of the centre of ocular rotation using geometric constructions, which can be implemented with a device featuring eye alignment references and placement means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an estimate is made with a device not based on visual axis positions, then the determination process is simple, but the precision of centre of rotation determination is poor
Solution Approach 1:
The patent introduces alignment references as intermediary elements that are positioned relative to the visual axis. These references serve as mediators between the visual axis (which cannot be directly observed) and the measurement device, enabling precise determination of the centre of rotation through their known geometric relationships with the fixation points and visual axis.
Solution Approach 2:
The patent replaces direct mechanical measurement of the centre of rotation with an optical-geometric system. Instead of mechanically locating the centre of rotation, the system uses alignment references, fixation points, and geometric constructions based on visual axis positions to calculate the centre of rotation position, substituting mechanical measurement with optical observation and mathematical computation.
2Ease of manufacture
If the centre of rotation is not precisely determined, then lens design and adaptation are simplified, but geometric aberrations increase
Solution Approach 1:
The patent performs preliminary determination of the centre of rotation position and visual axis alignment before lens design and manufacturing. By establishing the precise geometric relationships and centre of rotation position in advance, the lens can be designed and adapted to match these predetermined parameters, minimizing aberrations while maintaining manufacturing feasibility.
Solution Approach 2:
The patent enables precise adjustment of lens parameters (such as centre distance, axis orientation, and curvature) based on the determined centre of rotation position and visual axis alignment. By changing these parameters to match the individually measured geometric characteristics, the lens design optimizes visual performance while reducing geometric aberrations.
Data Source
Figure 1
Figure 1a
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AI summary
The invention relates to a method for determining the position of the centre of ocular rotation (1) with respect to a lens (2), said method establishing fixation points (3) of the vision of the eye (10) at two different angular measurement positions. The method further comprises measuring the angle between both positions, arranging references (6, 6a) to be aligned with the fixation point (3) in the different angular measurement positions of the eye using the visual axis (5), thereby obtaining two straight lines, measuring the distance between the references (6, 6a) when they have been aligned with the visual axis (5) and the fixation point (3), and drawing straight lines (100, 101) that form the same angle therebetween as the angular measurement positions of the eye, and pass through the ends of a first longitudinal straight line (55) that is equal to the distance between the two references (6, 6a).