Tear Film Thickness Measurement Using Wavelength-Dependent Interferometry
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Solution Overview
Problem
Current methods for diagnosing dry eye fail to accurately measure the lipid and aqueous layers of the tear film, particularly in large areas, and do not account for interactions between layers or evaporation rates, leading to inaccurate and unreliable results.
Innovation Solution
A system combining a spectrometer and an interferometer, or a spectrometer with a color camera, is used to measure the lipid and aqueous layers over large areas, incorporating broadband light and advanced optical elements to account for layer interactions and evaporation rates, providing accurate thickness measurements and evaporation rate analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional interferometric methods are used to measure tear film layers, then measurement can be performed without contact, but measurement precision is insufficient for large areas and does not account for layer interactions
Solution Approach 1:
The patent segments the tear film measurement into multiple discrete points across the ocular surface. By performing measurements at multiple locations rather than a single point, the system achieves both contactless operation and improved overall measurement precision through spatial sampling of the tear film layers.
Solution Approach 2:
The patent employs wavelength-dependent optical interferometry, changing the optical parameter (wavelength) to extract different information about the tear film layers. By analyzing interference patterns across multiple wavelengths, the system can distinguish between different layer thicknesses and account for interactions between the lipid and aqueous layers.
2Device complexity
If simple interferometric measurement is used, then device complexity is reduced, but reliability of dry eye diagnosis deteriorates due to inaccurate measurements
Solution Approach 1:
The patent replaces complex mechanical measurement systems with optical interferometry. By using light interference patterns to measure tear film thickness, the system achieves high reliability in diagnosis without requiring complex mechanical contact or invasive procedures, maintaining optical simplicity while ensuring diagnostic accuracy.
Solution Approach 2:
The system incorporates feedback by analyzing interference patterns and using this information to determine layer thicknesses and evaporation rates. The measured optical parameters are fed back into the diagnostic algorithm to reliably assess dry eye conditions, ensuring that the simplified optical system produces clinically reliable results.
3Loss of time
If measurement focuses on single point, then measurement time is reduced, but loss of information occurs about overall tear film structure and evaporation patterns
Solution Approach 1:
The patent performs preliminary rapid measurements at multiple discrete points across the tear film. By pre-sampling the tear film structure at various locations, the system captures comprehensive information about layer thickness and evaporation patterns quickly, minimizing measurement time while preserving essential spatial information.
Solution Approach 2:
The system performs measurements at more points than a single-point measurement would provide, using a multi-point sampling approach. This excessive sampling across the ocular surface ensures that no critical information about tear film structure or evaporation gradients is lost, while the measurements remain sufficiently rapid for clinical use.
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 system enables precise, reliable measurement of both lipid and aqueous layers, allowing for accurate determination of evaporation rates, thereby improving the diagnosis of dry eye conditions.
Implementation Method 1
The wavelength-dependent oscillations are created by the interactions of all combinations of reflections from the combined Microvilli height+aqueous+lipid layers, so that many interference frequencies can co-exist simultaneously
Implementation Method 2
wavelength-dependent optical interferometers that have been developed for in-vivo aqueous tear film and contact lens thickness analysis
Implementation Method 3
Other important aspects of the system such as measuring the evaporation rate and auto-focusing with fast feedback to allow reasonable measurement success rate after small movements or blinking, are missing
Data Source
AI summary
Apparatus and methods are described for performing tear film structure measurement on a tear film of an eye of a subject. A broadband light source (100) is configured to generate broadband light. A spectrometer (250) is configured to measure a spectrum of light of the broadband light that is reflected from at least one spot on the tear film, the spot having a diameter of between 100 microns and 240 microns. A computer processor (28) is coupled to the spectrometer and configured to determine a characteristic of the tear film based upon the spectrum of light measured by the spectrometer. Other applications are also described.