RNFL Thickness Normalization for TD-OCT Scans
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Solution Overview
Problem
Conventional time domain-OCT circle scans for retinal nerve fiber layer (RNFL) thickness measurements are prone to variability due to manual placement, making long-term follow-up and glaucoma progression analysis less reliable.
Innovation Solution
A method that normalizes RNFL thickness measurements of off-centered TD-OCT circle scans to a virtual location centered on the optic nerve head using a mathematical model of retinal tissue pattern and scan location matching algorithm, combining 2D and 3D optical coherence tomography data to reduce measurement variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual placement of TD-OCT circle scan is used, then ease of operation is improved, but measurement precision deteriorates due to off-centered scans
Solution Approach 1:
The patent introduces an automated image registration system that uses SD-OCT volume data as an intermediary to guide and normalize TD-OCT circle scan measurements. The SD-OCT data serves as a reference framework that automatically determines the correct circle scan location, eliminating manual placement errors while preserving operational simplicity through automated processing.
Solution Approach 2:
The patent replaces the manual mechanical placement of circle scans with an automated computational system. The image registration algorithm automatically calculates the optimal circle scan location based on SD-OCT volume data, substituting human operator actions with computational processes that consistently achieve precise, centered measurements.
2Reliability
If repeated RNFL thickness measurements are made at different time points, then detection of glaucoma progression is improved, but reliability deteriorates due to measurement variability
Solution Approach 1:
The patent performs preliminary SD-OCT volume scanning and image registration before conducting TD-OCT circle scan measurements. By pre-establishing the correct scan location through automated registration, the system ensures that all subsequent repeated measurements are taken from the same normalized position, eliminating location variability and improving long-term reliability.
Solution Approach 2:
The patent changes the measurement parameters by introducing normalized RNFL thickness values that are mathematically adjusted based on the registered circle scan location. This parameter transformation allows measurements taken at different time points to be directly comparable by referencing them to a standardized, normalized coordinate system.
3Measurement precision
If SD-OCT 3D volume scanning is used, then measurement precision is improved through automated localization, but device complexity increases
Solution Approach 1:
The patent makes the SD-OCT 3D volume scanning system multi-functional by using it for both diagnostic imaging and as a reference framework for normalizing TD-OCT measurements. The same SD-OCT device and data serve dual purposes: providing diagnostic information and guiding the circle scan localization, thereby reducing overall system complexity despite the advanced technology used.
Data Source
AI summary
A scan location matching (SLM) method identifies conventional time domain optical coherence tomography (TD-OCT) circle scan locations within three-dimensional spectral domain OCT scan volumes. A technique uses both the SLM algorithm and a mathematical retinal nerve fiber bundle distribution (RNFBD) model, which is a simplified version of the anatomical retinal axon bundle distribution pattern, to normalize TD-OCT thickness measurements for the retinal nerve fiber layer (RNFL) of an off-centered TD-OCT circle scan to a virtual location, centered on the optic nerve head. The RNFBD model eliminates scan-to-scan RNFL thickness measurement variation caused by manual placement of TD-OCT circle scan.