Fundus Observation Device with Overlapping OCT and Eyesight Measurement
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Solution Overview
Problem
Conventional fundus observation apparatuses cannot determine which site of the fundus is used to see a target, making it difficult to measure eyesight improvement after treatment, as they cannot obtain images at the eyesight measurement position and are affected by the eye's refractive power, leading to inaccurate measurements.
Innovation Solution
A fundus observation apparatus that includes a projection part to display a visual target, a light source for low-coherence light, an optical system for interference light generation, a scanning part for scanning the fundus, and a controlling part to overlap the visual target projection with the scanning region, allowing for precise eyesight measurement and image correlation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional fundus observation apparatus uses OCT to capture fundus images, then the internal morphology of the fundus can be visualized, but the apparatus cannot determine which specific site of the fundus corresponds to the eyesight measurement target
Solution Approach 1:
The patent combines the OCT imaging system with the eyesight measurement system into a single integrated apparatus. The OCT unit captures fundus images while the eyesight measurement unit projects targets and detects responses, and the control unit correlates the imaging data with measurement data to establish spatial correspondence between the captured fundus image and the eyesight measurement target position.
Solution Approach 2:
The control unit uses feedback from the eyesight measurement results to adjust and refine the correlation between the OCT image coordinates and the eyesight measurement target positions. By continuously comparing the measured eyesight values with the corresponding fundus image regions, the system optimizes the spatial mapping accuracy.
2Measurement precision
If the apparatus projects a visual target to the fundus for eyesight measurement, then eyesight values can be obtained, but the measurement is affected by the eye's refractive power leading to inaccurate results
Solution Approach 1:
The OCT system serves as an intermediary that provides direct optical path information about the fundus. By using OCT to capture the actual fundus image and correlate it with the eyesight measurement target position, the system bypasses the need to rely solely on refractive power calculations, as OCT directly images the fundus through the optical path without being affected by refractive errors in the same way traditional optometry methods are.
3Device complexity
If the apparatus captures only two-dimensional tomographic images with single-direction scanning, then the imaging process is simple, but three-dimensional fundus information cannot be obtained
Solution Approach 1:
The patent implements dynamic scanning where the scanning direction is changed between different measurement sessions. The first scanning captures a two-dimensional tomographic image in one direction, then the scanning direction is rotated to capture another two-dimensional image from a different angle. By combining multiple scans with different orientations, the system reconstructs three-dimensional fundus information without requiring a complex volumetric scanning system from the start.
4Ease of operation
If the apparatus uses subjective optometry for eyesight measurement, then eyesight values can be measured, but it cannot determine whether the measurement site corresponds to the treated fundus region
Solution Approach 1:
The patent merges the subjective optometry system with the OCT imaging system into an integrated apparatus. The eyesight measurement unit projects targets and records responses using simple subjective methods, while the OCT unit simultaneously captures fundus images. The control unit correlates the eyesight measurement data with the OCT image data, preserving spatial location information by mapping measurement results to specific coordinates in the fundus image.
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 accurate measurement of eyesight by forming images at the eyesight measurement site on the fundus, accounting for refractive power variations, and correlating images with measured eyesight values, thus determining treatment effectiveness.
Implementation Method 1
generates interference light by superposing the reflected signal light and reference light
Implementation Method 2
optical coherence tomography that forms images of the surface morphology and internal morphology of an object by using a light beam from a laser light source
Data Source
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AI summary
The controller 210 changes the projection region of the Landolt ring T on the fundus Ef by changing, based on the scanning region R, the relative display position of the Landolt ring T and the fixation target V on the LCD 39, thereby overlapping the scanning region R and the projection region each other. Under this condition, the fundus observation apparatus 1 executes the eyesight measurement and OCT measurement, obtains the eyesight value at the site of interest of the fundus Ef, and forms a tomographic image of the fundus Ef in the scanning region R. The controller 210 stores in the storage 212 the eyesight value at the site of interest and the tomographic image corresponding to the scanning line closest to the measurement position of eyesight while correlating them with each other, and allows them to be displayed on the display device 3.