Refractometer Distance Measurement Using Scheimpflug Camera
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Solution Overview
Problem
Existing refractometers face inaccuracies in measuring eye refraction due to insufficient distance measurement between the eye and the device, as current systems only measure head distance, leading to unsatisfactory correction of refraction data.
Innovation Solution
A refractometer with an integrated distance measuring device that uses a slit projection device and a Scheimpflug camera to accurately measure the distance between the refractometer and the eye's cornea or lens, enabling precise correction of refraction data, and optionally includes a keratometer for additional measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an ultrasonic transceiver and optical distance measuring system are used to measure the distance between the forehead and the measuring system, then the distance measurement function is provided, but the measurement precision is insufficient because only head distance is measured without definitive information on the position of the eye
Solution Approach 1:
The patent introduces a camera as an intermediary device to capture images of the eye, which serves as a mediator between the distance measuring system and the eye position determination. The camera images provide visual information about eye position that complements the ultrasonic and optical distance measurements, enabling more accurate determination of eye position relative to the refractometer.
Solution Approach 2:
The patent combines multiple measurement functions (ultrasonic distance measurement, optical distance measurement, and camera imaging) into a single integrated system. This multi-functional approach allows the device to simultaneously perform head distance measurement, eye distance measurement, and eye position visualization, resolving the limitation of single-function distance measurement systems.
2Reliability
If the distance between the head and the refractometer is measured, then a distance measurement is provided, but the reliability of refraction data correction is insufficient because the head position does not definitively indicate the eye position
Solution Approach 1:
The patent implements feedback by using camera images to verify and adjust the distance measurements. The visual feedback from the camera allows operators to confirm that the measured distance corresponds to the correct eye position, and to make real-time adjustments to ensure accurate refraction data correction. This feedback loop significantly improves the reliability of the correction process.
Solution Approach 2:
The patent replaces purely mechanical/physical distance measurement systems (ultrasonic and optical sensors) with an optical imaging system (camera) that provides direct visual information about eye position. This substitution allows for more intuitive and reliable determination of eye position, as the camera images directly show the eye's location and orientation rather than inferring it from head distance 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
The solution significantly improves measuring accuracy by allowing precise distance measurement between the refractometer and the eye, correcting refraction data effectively and enabling additional measurements like cornea thickness assessment, thereby enhancing the reliability of refractometry.
Implementation Method 1
A light pattern is produced with the aid of an optical projection device, for example, light-emitting diodes, and projected on the retina of the eye. The projection of the light pattern is realized such that the light pattern is focused on the retina. The light pattern reflected on the retina is viewed through the eye lens by means of an optical viewing device
Implementation Method 2
The light pattern reflected on the retina is viewed through the eye lens by means of an optical viewing device that comprises a photoelectric sensor, for example, a video camera, such that an image pattern is projected on the photoelectric sensor. This image pattern is recorded with the photoelectric sensor
Data Source
AI summary
The invention pertains to a refractometer (01) for determining the refraction properties of an eye (02) of a patientwith an optical projection device (03) that comprises at least one light source (08) that produces a light pattern, wherein the light pattern of the projection device (03) can be projected on the retina of the eye (02) and focused thereon,with an optical viewing device (04) that comprises at least one photoelectric sensor (12), wherein the light pattern reflected on the retina of the eye (02) can be viewed through the cornea and the lens of the eye with the viewing device (4) and projected on the photoelectric sensor (12) in the form of an image pattern,with an evaluation device for evaluating the image pattern recorded by the photoelectric sensor (12) and deriving the refraction properties of the eye, andwith a distance measuring device for determining the distance between the refractometer (01) and the patient. The distance measuring device (16, 17) makes it possible to measure the distance between the refractometer (01) and the eye (02).