AS-OCT Angle Classification for PAC Risk Assessment
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Solution Overview
Problem
Current methods for diagnosing angle-closure in eyes, such as gonioscopy, are limited in precision due to factors like slit-lamp illumination and anatomic variations, leading to variable detection of iris trabecular contact and subsequent risk assessment for primary angle closure (PAC) and primary angle closure glaucoma (PACG).
Innovation Solution
A computerized method using 360° imaging from anterior segment-optical coherence tomography (AS-OCT) to analyze cross-sectional images of the eye, identifying the scleral spur and segmenting cornea and iris boundaries to determine angle opening distance and trabecular iris space area, classifying angles as open, narrow, or closed, and applying a regression model to assess the risk of PAC/PACG development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gonioscopy assessment is used for diagnosing angle-closure, then the diagnostic process is simple and widely available, but the measurement precision and detection accuracy of iris trabecular contact are low
Solution Approach 1:
The patent replaces the mechanical gonioscopy system with an optical coherence tomography (OCT) imaging system. The OCT device uses low-coherence interferometry to obtain cross-sectional images of the anterior chamber angle, eliminating the need for manual gonioscopy assessment. This substitution provides objective, quantifiable measurements of angle anatomy including iris trabecular contact detection, angle opening distance, and trabecular meshwork visualization, thereby improving measurement precision while maintaining ease of operation through automated image analysis.
2Adaptability or versatility
If slit-lamp illumination is used during gonioscopy, then the examination can be performed with standard equipment, but the illumination affects the observation of iris trabecular contact and introduces diagnostic variability
Solution Approach 1:
The patent introduces OCT imaging as an intermediary technique that bypasses the limitations of slit-lamp illumination. The OCT system uses low-coherence light interferometry to penetrate and image the anterior chamber angle structures in cross-section, providing illumination-independent visualization. This intermediary imaging modality eliminates the confounding effects of slit-lamp lighting on iris trabecular contact observation while remaining compatible with standard ophthalmic imaging workflows.
3Productivity
If manual clinical judgement is used to assess angle closure on gonioscopy, then the diagnostic process is quick, but the reliability and consistency of iris trabecular contact detection are low due to subjectivity
Solution Approach 1:
The patent implements automated image analysis algorithms that perform self-assessment of OCT images to detect iris trabecular contact, measure angle opening distance, and evaluate anterior chamber angle anatomy. The system automatically processes the cross-sectional images, applies segmentation algorithms to identify anatomical structures, and generates quantitative measurements without requiring manual clinical judgement. This self-service approach maintains rapid diagnostic throughput while significantly improving reliability and consistency through objective, reproducible measurements.
Solution Approach 2:
The patent incorporates automated feedback mechanisms where the OCT imaging system provides real-time quantitative measurements and visual feedback on angle anatomy. The system generates objective data on angle opening distance, iris trabecular contact status, and trabecular meshwork configuration, which can be immediately used for risk assessment. This feedback loop eliminates the subjectivity of manual judgement while maintaining diagnostic efficiency through automated interpretation of imaging data.
4Ease of manufacture
If corneal indentation occurs during gonioscopy, then the contact lens placement is simple, but the anterior chamber angle is artificially widened and obscures the observation of iris trabecular contact
Solution Approach 1:
The patent replaces the mechanical contact lens-based gonioscopy system with non-contact OCT imaging. The OCT device uses optical interference to image the anterior chamber angle without requiring physical contact with the cornea. This eliminates the confounding effect of corneal indentation that artificially widens the angle and obscures iris trabecular contact. The optical-based measurement preserves the natural angle configuration while providing accurate visualization of anatomical structures.
5Ease of operation
If anatomic variations in anterior segment are not accounted for, then the diagnostic criteria can be standardized, but the detection accuracy varies across different eye configurations
Solution Approach 1:
The patent applies local quality analysis by segmenting the anterior chamber angle into distinct anatomical regions and evaluating each region's specific characteristics. The OCT imaging provides cross-sectional views that capture local anatomical variations in iris configuration, trabecular meshwork structure, and angle depth. The automated analysis system adapts its measurement parameters and interpretation criteria to the specific anatomical configuration of each patient's eye, accounting for variations in anterior chamber depth, lens vault, and iris insertion position while maintaining standardized diagnostic output.
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
This approach provides a more precise risk assessment for PAC/PACG, reducing diagnostic variability and informing treatment decisions by accurately differentiating between closed and narrow angles, thereby improving patient outcomes.
Implementation Method 1
anterior segment-optical coherence tomography (AS-OCT) is more precise than gonioscopy to reveal the presence and the extent of ITC
Data Source
AI summary
The subject invention pertains to a novel angle-closure detection method for risk assessment of primary angle closure (PAC) or primary angle closure glaucoma (PACG) to inform treatment decisions. According to certain embodiments, a plurality of cross-sectional images of the anterior segment of an eye centered at the pupil with preferably even radial separations are obtained from optical coherence tomography imaging. After identifying the position of scleral spur from the cross-sectional image captured at each angle-location, the anterior chamber angles are analyzed. Each angle-location of the eye is classified as (i) closed angle, (ii) narrow angle, or (iii) open angle. The extents of narrow angles and closed angles among all angle-locations across the 360° radial space are computed. Based on the extents of narrow angles and closed angles, a regression model is applied to compute the risk of PAC/PACG development.