Anterior Segment OCT Alignment Using Iris Edge Detection

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Solution Overview

Problem

Existing ophthalmic apparatuses require manual and burdensome preparatory operations for applying optical coherence tomography (OCT) to a living eye, especially the anterior segment, which can be challenging when no expert is present at the examination site.

Innovation Solution

An ophthalmic apparatus with automated preparatory operations, including an optical coherence tomography (OCT) system, image constructing and evaluating units, and movement mechanisms to set and adjust scan areas, reduce the burden by automating the alignment and image quality assessment for OCT scans on the anterior segment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual preparatory operations are performed by an expert, then alignment accuracy and image quality are improved, but the burden on the subject and examiner increases and the procedure becomes time-consuming

Engineering Contradiction:
Improvealignment accuracyVSAvoidoperational burden
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system automatically performs alignment and scan area setting by detecting the iris outer edge and corner angle image positions without requiring expert manual adjustment. The apparatus serves itself by using its own imaging capabilities to guide the preparatory operations, thereby reducing the burden on operators while maintaining alignment accuracy.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Manual mechanical adjustment operations are replaced with automated image processing and detection algorithms. The system uses computer vision techniques to detect anatomical features and automatically calculate scan parameters, substituting the expert's manual positioning with algorithmic determination.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If automated preparatory operations are implemented, then the burden on subject and examiner is reduced, but the complexity of the device increases

Engineering Contradiction:
Improveoperational burdenVSAvoidsystem complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The imaging system serves multiple functions: it captures images for diagnostic purposes and simultaneously uses those same images for alignment guidance and scan area determination. The corner angle image detection and iris outer edge detection capabilities are integrated into the existing imaging pathway, allowing the same hardware to perform both clinical imaging and preparatory alignment tasks.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The corner angle image serves as an intermediary element that bridges the gap between raw imaging data and alignment control. By detecting this specific anatomical feature and using its position relative to the iris outer edge, the system creates a simple geometric reference that guides scan area setting without requiring complex artificial intelligence or external alignment devices.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If multiple detection and evaluation steps are performed, then scan accuracy and image quality are improved, but the examination time increases

Engineering Contradiction:
Improvescan accuracyVSAvoidexamination time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs detection of the iris outer edge and corner angle image, and calculates the scan area in advance before the actual OCT scan is executed. This preliminary setup ensures that when the scan begins, all alignment and parameter settings are already optimized, preventing the need for time-consuming adjustments during the examination.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the detected corner angle image position and iris outer edge to automatically adjust and determine the scan area. This closed-loop approach ensures scan accuracy by continuously referencing anatomical landmarks, while the automation of this feedback process prevents time loss through manual iteration.

Inventive Principle:
Principle #23Feedback

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 reduces the burden on subjects and examiners by automating preparatory operations, ensuring accurate and efficient OCT scans on the anterior segment.

Implementation Method 1

an optical coherence tomography (OCT) optical system configured to apply an OCT scan to an anterior segment of an eye

Methodology Applied
Scientific EffectOptical coherence tomography:

Data Source

PatentEP3811850B1Ophthalmic device, control method therefor, program, and recording medium
Publication Date: 2025.11.12 TOPCON CORPORATION
  • EP3811850B1 patent drawingFigure 1
  • EP3811850B1 patent drawingFigure 2
  • EP3811850B1 patent drawingFigure 3A

AI summary

A scanning area setting unit of an illustrative ophthalmic device sets the scanning area to a region passing through the outer edge of the iris. A first scanning control unit controls an OCT optical system such that OCT scanning is applied to this scanning area. An image quality evaluation unit calculates an image quality evaluation value for an image that is based on the OCT scanning of the scanning area. An angle image detection unit detects an angle image by analyzing the image that is based on the OCT scanning of the scanning area. A position determination unit determines whether the angle image is positioned within a first area in the image frame. A second scanning control unit controls the OCT optical system such that in cases in which the image quality evaluation value is equal to or greater than a prescribed threshold value and the angle image is positioned within the first area, OCT scanning using a prescribed pattern is applied to the anterior segment of the eye.