Tear Film Lipid Layer Thickness Measurement Using Optical Interferometry
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Solution Overview
Problem
Current methods for measuring tear film lipid layer thickness are qualitative or semi-quantitative, lack precision, and are not suitable for diagnosing dry eye disease effectively, particularly in the central cornea where tear film thinning is maximal.
Innovation Solution
A method and system using a wavelength-dependent optical interferometer to measure the relative reflectance spectrum of the tear film, convert it to an absolute reflectance spectrum, and compare it to theoretical spectra to determine lipid layer thickness, with a b-term correction for curved surfaces, enabling accurate and rapid lipid layer thickness determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If quantitative methods are used to measure tear film lipid layer thickness, then measurement precision is improved, but measurement time increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing theoretical reflectance spectra for various lipid layer thicknesses before actual measurement. During measurement, the system quickly compares the measured spectrum against this pre-computed library to identify the best match, avoiding time-consuming real-time calculations while maintaining high precision in determining lipid layer thickness
Solution Approach 2:
The patent uses copying by creating a theoretical model (copy) of the reflectance spectrum for different lipid layer thicknesses. This theoretical spectrum copy is then compared against the actual measured spectrum to determine the lipid layer thickness, enabling rapid measurement without direct complex calculation of the physical sample during measurement
2Measurement precision
If existing quantitative measurement methods are used, then measurement accuracy is improved, but the methods cannot effectively diagnose dry eye disease in the central cornea
Solution Approach 1:
The patent applies local quality by specifically adapting the measurement system to target the central cornea region, where tear film thinning and breakup due to evaporation is maximal. The interferometer is configured to measure reflectance spectra from this specific location, providing locally optimized diagnostic capability for dry eye disease where it is most needed
3Device complexity
If qualitative or semi-quantitative methods are used for lipid layer measurement, then device complexity is reduced, but diagnostic sensitivity and accuracy decrease
Solution Approach 1:
The patent replaces complex mechanical or manual analysis methods with an optical interferometry system that automatically measures reflectance spectra and uses computational algorithms to determine lipid layer thickness. This substitution of mechanical/manual processes with optical and computational methods achieves high diagnostic sensitivity while keeping the physical device relatively simple
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 fast, accurate, and precise measurement of tear film lipid layer thickness, suitable for evaluating the effects of novel tear formulas, eye drops, and contact lenses, and aiding in intraocular lens selection based on light attenuation properties.
Implementation Method 1
measuring a tear film aqueous plus lipid layer relative reflectance spectrum using a wavelength-dependent optical interferometer
Implementation Method 2
measuring a tear film aqueous plus lipid layer relative reflectance spectrum
Data Source
AI summary
A method for determining reflectivity of a tear film lipid layer of a patient and recommending a course of treatment based on the same. The method includes the steps of: measuring a tear film aqueous plus lipid layer relative reflectance spectrum using a wavelength-dependent optical interferometer; converting the measured tear film aqueous plus lipid layer relative reflectance spectrum to a calculated absolute reflectance spectrum; comparing the calculated absolute reflectance spectrum to a theoretical absolute lipid reflectance spectrum to determine a tear film lipid layer thickness; and determining a reflectivity value for the tear film lipid layer thickness at a first wavelength of light corresponding to ultraviolet, violet, or blue light.