Flexible Contact Lens Sensor for Intraocular Pressure Monitoring
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Solution Overview
Problem
Existing methods for monitoring intraocular pressure (IOP) require frequent calibration and adaptation, and they often impair the eye with significant central impact, limiting their ability to measure other biomechanical properties effectively.
Innovation Solution
A contact lens device with a flexible sensor that measures force values and indentation depths using a viscoelastic model to determine corneal tension, allowing for minimal indentation and reduced calibration efforts, while also monitoring other eye properties by analyzing the movement and acceleration of the eyelid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If central applanation measurement is used, then IOP can be measured, but significant dependence on corneal curvature and stiffness exists requiring frequent calibration
Solution Approach 1:
The measurement process is segmented into multiple phases (approach, contact, indentation, release) with distinct measurement objectives. Different parameters are measured at different stages, reducing the need for continuous calibration by capturing baseline information during approach and contact phases.
Solution Approach 2:
The lid closure action is utilized as a preliminary event that naturally positions the sensor and establishes initial contact conditions. This preliminary mechanical action provides reference data for subsequent IOP calculations, reducing dependency on separate calibration procedures.
2Measurement precision
If contact lens sensor with elevation is used, then peripheral corneal pressure can be measured, but adaptation and recalibration remain burdensome
Solution Approach 1:
The system performs self-calibration by utilizing the natural eyelid closure mechanics and corneal response characteristics. The sensor automatically adapts to individual eye properties through multiple measurement cycles, eliminating manual recalibration requirements and making the device easier to operate.
Solution Approach 2:
The system incorporates feedback loops that continuously monitor measurement consistency and automatically adjust calibration parameters. This feedback mechanism maintains measurement accuracy without requiring user intervention for recalibration, significantly improving ease of operation.
3Adaptability or versatility
If multiple biomechanical properties are monitored, then comprehensive eye assessment is achieved, but measurement complexity increases
Solution Approach 1:
The sensor system is designed with multi-functionality to measure multiple biomechanical properties (IOP, corneal stiffness, viscoelastic parameters) using the same hardware platform. This universal design achieves comprehensive eye assessment without proportionally increasing device complexity, as all measurements are derived from the same force-time data set.
Solution Approach 2:
Different biomechanical properties are extracted by analyzing the same raw data through different parameter transformations and mathematical models. By changing the analysis parameters rather than adding physical sensors, the system achieves versatility while maintaining relatively simple device architecture.
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
This approach provides continuous, accurate monitoring of IOP with reduced calibration needs and minimal impact on the eye, enabling the assessment of additional biomechanical properties through a viscoelastic model that accounts for the eye's viscoelastic behavior.
Implementation Method 1
the measuring device comprising a force detector in operative engagement with a protrusion directed towards the cornea
Implementation Method 2
A contact lens device with a flexible sensor that measures force values and indentation depths using a viscoelastic model to determine corneal tension
Data Source
Figure 1~4
Figure 2~3
Figure 5~11
AI summary
A contact lens shaped measuring device (1) comprises sensor (3) having a protrusion (14) towards the cornea (22). The measuring device (1) is flexible to a degree that it is flattened by a closing eye lid and the protrusion creates an indentation of the cornea. The occurring force on the protrusion is measured by the sensor. Applying a constant lid acceleration/deceleration model to the movement of the lid and a mechanical model to the cornea, the tension of the cornea is determined and deduced from the force measured with the lid closed, yielding the true intraocular pressure. In an alternative, the protrusion is characterized by a discontinuity in its shape, or the sensor is subdivided, each subsensor being characterized by a protrusion of different shape. With the values obtained as extrema and at the discontinuity or with different protrusions, the cornea tension can be obtained by a (linear) extrapolation.