Applanation Tonometer with Piezo Optical Sensor
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Solution Overview
Problem
Existing applanation tonometers, such as the Goldmann applanation tonometer, face issues with jamming moving parts, long dwell time on the cornea, and the need for topical anesthesia, which increases patient discomfort and safety concerns while measuring intraocular fluid pressure (IOP).
Innovation Solution
An applanation tonometer with no moving parts, utilizing a conical prism with a piezo element and a light ring, where a laser module supplies light beams that are reflected and decoupled based on the contact area, providing force and area data pairs for accurate IOP measurement with minimal contact time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Goldmann applanation tonometer is used to measure IOP, then accurate measurement is achieved, but moving parts may jam and require long dwell time on the cornea
Solution Approach 1:
The patent removes all moving parts from the tonometer system. The contact tip is held stationary by a support surface, and measurement is achieved by moving the support surface toward the cornea until contact is made, eliminating mechanical components that can jam or fail.
Solution Approach 2:
The patent replaces mechanical moving parts with an optical system. A light source illuminates the contact tip, and a detector measures light transmission changes to determine when applanation is achieved, substituting mechanical motion with optical detection.
2Measurement precision
If the contact tip dwells on the cornea for several seconds to ensure accurate measurement, then measurement accuracy is improved, but patient discomfort increases and topical anesthesia is required
Solution Approach 1:
The patent performs the measurement in a single rapid touch contact with the cornea. The support surface moves toward the cornea until contact is detected by the optical system, achieving measurement in one quick action rather than requiring prolonged dwell time.
Solution Approach 2:
The patent pre-positions the contact tip and support surface so that measurement can be achieved by simply moving the support surface forward. The optical detection system is already in place and ready to detect contact, enabling immediate measurement without preliminary adjustments or prolonged contact.
3Measurement precision
If multiple touch contacts are made to acquire force and area data, then measurement accuracy is improved, but measurement time increases and productivity decreases
Solution Approach 1:
The patent continuously moves the support surface toward the cornea while the optical detector continuously monitors light transmission. This continuous action allows force and area data to be collected simultaneously during a single touch, eliminating the need for multiple separate measurements.
Solution Approach 2:
The patent combines the collection of force data (via piezoelectric sensor) and area data (via optical detection of light transmission changes) into a single simultaneous measurement process. Both parameters are acquired during one continuous touch contact, merging what would traditionally require multiple separate measurements.
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 solution allows for accurate, jam-free, and quick IOP measurements with reduced patient discomfort by eliminating the need for prolonged contact and topical anesthesia, using the force and area data pairs to calculate IOP efficiently.
Implementation Method 1
A piezo element lies opposite the contact tip of the prism and is responsive to the force generated as the contact tip is pressed against the cornea
Implementation Method 2
A light ring having a light absorbing center, a light-absorbing outside area, and a light-transmitting area between the light-absorbing center and outside area is located behind the contact tip of the prism to allow incoming and outgoing light beams to be transmitted inwardly through and outwardly from the prism
Implementation Method 3
a laser module supplies light beams that are reflected and decoupled based on the contact area, providing force and area data pairs for accurate IOP measurement
Data Source
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Figure 5~6
AI summary
An applanation tonometer (I) for measuring intraocular pressure (IΟΡ) so that the health of a human or animal eye can be determined. The applanation tonometer (I) includes a prism (9) having a contact rip (10) at one end to be moved into contact with and lightly touched against the cornea of the eye. Incident laser light (76) is transmitted inwardly through the prism to the contact tip (10) at which some of the light (82) is decoupled and lost through the contact tip depending upon the area of contact between the contact tip arid the cornea. The remaining light (84) is reflected by the contact tip outwardly through the prism. A photo detector (64) which is responsive to the light (84) reflected by the contact tip (10) of the prism (9) and a force detector (44) which is responsive to the pressure at the area of contact between the contact tip and the cornea generate paired force and area data pairs that are processed to measure IOP.