Ophthalmic Imaging Apparatus Eye Movement Correction
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Solution Overview
Problem
Ophthalmic imaging apparatuses face challenges in acquiring accurate tomographic images due to eye movement during scanning, leading to positional deviations and inability to generate appropriate averaged images when the reference image is acquired at a deviated position.
Innovation Solution
An ophthalmic imaging apparatus equipped with an OCT optical system, an observation optical system, and a processor that detects positional deviations between reference and acquired images, selects images within a permissible range for synthesis, and corrects scanning positions to ensure accurate image acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple tomographic images are acquired for averaging to reduce noise, then noise reduction is improved, but image quality deteriorates when the subject eye moves during scanning causing positional deviation
Solution Approach 1:
The system uses front images captured by the observation optical system as feedback to detect positional deviations of the subject eye. This feedback mechanism allows the system to identify when images are acquired at incorrect positions and exclude them from averaging, thereby maintaining both noise reduction and positional accuracy.
Solution Approach 2:
The system captures front images simultaneously with tomographic images before completing the full scanning process. This preliminary action allows the system to detect positional deviations early and determine which tomographic images should be excluded from averaging, preventing the inclusion of misaligned images in the final averaged result.
2Reliability
If the scanning process is extended to acquire multiple images for averaging, then noise reduction is improved, but the time required for imaging increases
Solution Approach 1:
The system performs a partial averaging process by acquiring multiple tomographic images and front images, then selectively averaging only those images that meet the positional accuracy criteria. This partial action approach avoids wasting time on images that would be excluded anyway, while still achieving noise reduction from the valid images.
3Productivity
If the permissible range for positional deviation is widened to accept more images for averaging, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The system dynamically adjusts the evaluation criteria by comparing positional deviations against a predetermined permissible range. This parameter-based approach allows the system to maintain strict positional accuracy requirements while efficiently processing multiple images, achieving both productivity and precision by objectively evaluating each image's positional 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
The apparatus effectively selects and synthesizes tomographic images acquired at the correct position, reducing noise and ensuring high-precision imaging even with eye movement, thereby improving the accuracy of averaged and super-resolution images.
Implementation Method 1
an optical coherence tomography (OCT) optical system configured to acquire a tomographic image of a subject eye by using interference between a measurement light which is emitted to the subject eye and a reference light
Data Source
AI summary
There is provided an ophthalmic imaging apparatus including an optical coherence tomography (OCT) optical system for acquiring a tomographic image of a subject eye, an observation optical system configured to acquire a front image of the subject eye. The apparatus functions as an image generation unit which repeatedly generates the tomographic image based on an output signal from the OCT optical system, and repeatedly generates the front image based on an output signal from the observation optical system, a determination unit which detects a positional deviation between a reference front image and each of front images generated by the image generation unit, and determines consecutiveness of the front images whose positional deviation satisfies a permissible range, and a selection process unit which selects one of multiple tomographic images generated by the image generation unit, based on a determination result by the determination unit.