Rebound Tonometer Tilt Correction for Accurate IOP Measurement
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Solution Overview
Problem
Rebound tonometers require significant skill and time for proper alignment, and measurements are inaccurate when the measurement axis is tilted due to gravitational effects, especially when the patient's head is tilted or gaze is inclined.
Innovation Solution
Incorporating a tilt sensor into the rebound tonometer to detect the direction and degree of tilt, applying a tilt correction factor to the basic IOP measurement to compensate for gravitational effects, thereby improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the measurement axis is tilted to accommodate patient head tilt or inclined gaze, then alignment with the eye is achieved, but measurement accuracy deteriorates due to gravitational effects on the probe
Solution Approach 1:
The system detects tilt angle as a parameter change and applies a corresponding correction factor to compensate for gravitational effects. The correction factor is calculated based on the detected tilt angle and applied to the IOP measurement to maintain accuracy despite measurement axis tilt.
2Measurement precision
If strict alignment requirements are enforced to maintain measurement accuracy, then measurement precision is improved, but measurement efficiency deteriorates due to repeated alignments and extended measurement time
Solution Approach 1:
The system converts the previously harmful tilt condition into a beneficial opportunity by applying correction factors. Measurements that were previously discarded due to tilt can now be used with corrected values, improving efficiency while maintaining accuracy.
3Measurement precision
If multiple measurements are taken to refine alignment and ensure accuracy, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The system performs preliminary detection of tilt angle before taking measurements and prepares the appropriate correction factor in advance. This preliminary action eliminates the need for repeated measurements to verify alignment, saving time while ensuring accuracy.
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
Enhances measurement efficiency and accuracy by allowing measurements at slight tilt angles, reducing the need for repeated alignments and improving usability.
Implementation Method 1
sensing a direction and a degree of tilt of the measurement axis
Implementation Method 2
The coil may be energized momentarily to propel the probe toward the cornea by electromagnetic force
Implementation Method 3
after energizing current to the coil is shut off, a current may be induced in the coil by the moving probe to provide a detectable voltage signal
Data Source
AI summary
A rebound tonometer is improved by providing a tilt signal from a tilt sensor of the rebound tonometer to a signal processor of the rebound tonometer, and configuring the signal processor to apply a tilt correction factor to a basic IOP measurement value calculated by the signal processor to provide a final IOP measurement value, wherein the tilt correction factor depends on a tilt direction and a degree of tilt indicated by the tilt signal. The final reported IOP measurement value takes into account gravitational effects on the probe due to tilt. As a result, measurements made at relatively small tilt angles are now usable, thereby improving efficiency. A corresponding rebound tonometry measurement method, and a method of calibrating a rebound tonometer for tilt correction, are also disclosed.