Fiber Optic Pressure Probe for Cornea-Independent Eye Pressure Measurement
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Solution Overview
Problem
Existing applanation tonometers, both contact and non-contact types, rely on corneal measurements which are influenced by corneal shape variations, leading to inaccurate intraocular pressure readings, especially in cases like LASIK surgery or normal-tension glaucoma.
Innovation Solution
A probe for intraocular pressure measurement using a fiber optic pressure sensor with a needle tube having a 30 to 34 G gauge needle tip, where the pressure receiver is positioned at the needle tip, allowing direct measurement through the vitreous body, minimizing invasiveness and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If applanation tonometers measure intraocular pressure through the cornea, then the measurement can be performed non-invasively or with minimal invasiveness, but the measurement accuracy deteriorates due to corneal shape variations
Solution Approach 1:
The invention extracts the pressure measurement function from the corneal interface and relocates it to the vitreous body. By puncturing the eye and placing the pressure receiver directly in the vitreous cavity, the measurement is decoupled from corneal shape influences, achieving high accuracy without compromising invasiveness since the needle tube is thin (30-34G)
Solution Approach 2:
The needle tube serves as an intermediary structure that bridges the external measurement device and the internal vitreous body. It provides a pathway to reach the pressure measurement location while maintaining minimal invasiveness due to its thin gauge (30-34G), and the fiber optic pressure sensor acts as an intermediary transducer converting pressure to optical signals
2Device complexity
If conventional tonometers rely on corneal measurements, then the device structure remains simple and easy to operate, but measurement reliability deteriorates in post-surgical eyes and normal-tension glaucoma cases
Solution Approach 1:
The measurement function is extracted from the corneal interface and relocated to the vitreous body, eliminating dependency on corneal shape. This extraction resolves the reliability issue in post-surgical eyes and normal-tension glaucoma cases where corneal measurements are unreliable
Solution Approach 2:
The mechanical contact measurement system (prism or air puff on cornea) is replaced with an optical-based fiber optic pressure sensor in the vitreous body. This substitution eliminates mechanical dependencies on corneal properties while maintaining device operability
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
Enables highly accurate intraocular pressure measurement by bypassing corneal influence, suitable for cases where conventional tonometers fail, such as normal-tension glaucoma and post-surgical eyes, with potential for new glaucoma treatment methods.
Implementation Method 1
a fiber optic pressure sensor having a pressure receiver provided at the distal end of an optical fiber
Data Source
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AI summary
There is provided an instrument capable of measuring intraocular pressure of a subject with low invasiveness at higher accuracy. The instrument is a probe for intraocular pressure measurement 10 including a fiber optic pressure sensor 30 having a pressure receiver 38 provided at the distal end of an optical fiber 37 and a needle tube 20 that covers the pressure receiver 38 side of the fiber optic pressure sensor 30 and accommodates the pressure receiver 38 inside. The needle tube 20 has a needle tip 21 to be punctured into a subject at the distal end thereof and has a gauge size of 30 to 34 G. The pressure receiver 38 is provided at a position of the needle tip 21 inside the needle tube 20. The fiber optic pressure sensor 30 and the needle tube 20 are fixed on the proximal end 23 side of the needle tube 20 by a joint between the optical fiber 37 and the needle tube 20.