Visual Axis Measurement for Bifocal Lens Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining the placement of bifocal lens segments in progressive bifocal eyeglasses often result in misalignment between the optical axis and visual axis, leading to blurriness and dissatisfaction among users, as they rely solely on pupillary axis measurement, which is not always aligned with the visual axis.
Innovation Solution
A visual axis and alignment measurement system that includes a device with adjustable slits and a coupling mechanism, allowing for the measurement of the distance between the visual axes of a patient's eyes, ensuring accurate alignment of bifocal lens segments with the visual axis rather than the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If optical (pupillary) axis measurement is used to determine bifocal lens segment placement, then the measurement process is simple and quick, but the alignment accuracy with the visual axis deteriorates, causing blurriness and customer dissatisfaction
Solution Approach 1:
The patent introduces an intermediary device consisting of adjustable slits positioned in front of the patient's eyes. These slits act as a mediator between the optical axis measurement and the visual axis, allowing the patient to manually adjust them until they align with their actual line of sight (visual axis) when viewing a target at reading distance. This intermediary mechanism enables accurate visual axis measurement without requiring complex automated tracking systems.
Solution Approach 2:
The patient themselves performs the alignment task by manually adjusting the slits to match their visual axis when viewing a target. This self-service approach eliminates the need for complex external measurement equipment while ensuring accurate alignment, as the patient's own visual system determines the correct positioning.
2Measurement precision
If visual axis measurement device with adjustable slits is used, then the alignment accuracy with visual axis is improved, but the device complexity increases
Solution Approach 1:
The measurement device is segmented into simple, discrete components: two separate adjustable slits (one for each eye), a coupling mechanism, and a measurement scale. Each component has a single, clear function. The slits can be independently adjusted, and the coupling mechanism simply translates the adjustment of one slit to the other while maintaining their relative positions. This segmentation keeps the device structurally simple while achieving accurate visual axis measurement.
Solution Approach 2:
The adjustable slits serve as a simple intermediary mechanism that bridges the gap between the complex biological visual axis and the simple measurement process. Rather than using complex cameras or sensors to track eye movement, the slits provide a straightforward mechanical way for the patient to indicate their visual axis alignment.
Data Source
AI summary
A visual axis and alignment measurement system and method of using same are disclosed. In particular, a visual axis measurement system of the present disclosure includes a visual axis measurement device and a near point target. The visual axis measurement device includes a pair of opaque lenses, each having a slit therein, that are adjustably coupled via a coupling mechanism. The visual axis measurement device also includes a linear measurement device. Via self-adjustment, the patient may align the respective slits for his/her dominant and non-dominant eyes along his/her visual axes until the near point target is in focus. After which, the distance between the centers of the slits is measured in order to determine accurately the placement of bifocal lens segments within eyeglass lenses. In doing so, it is ensured that the prescription for, for example, progressive bifocal corrective lenses, which have narrow viewing areas, is correct.