OCT Scanning Pattern for Retinal Tissue Stability
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Solution Overview
Problem
Optical coherence tomography (OCT) scans of the eye are challenging when using visible light due to the patient's natural reaction of following the laser, which causes eye movement, making it difficult to maintain absolute stability required for accurate three-dimensional imaging.
Innovation Solution
A novel scanning pattern that ensures the fovea, the most sensitive region, is scanned last, using alternating or spiral patterns to minimize eye movement, employing a combination of line and frame scanners controlled by a programmable computer to adjust the scanning sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional scanning pattern is used, then the scanning process is simple and fast, but the patient's eye moves to follow the laser, causing instability and poor image quality
Solution Approach 1:
The patent inverts the conventional scanning approach by scanning from the periphery toward the fovea rather than the typical center-out pattern. This reversal exploits the patient's natural fixation tendency on the fovea, keeping the eye stationary while the laser scans outward regions, thereby improving image stability without requiring complex additional hardware
Solution Approach 2:
The scanning pattern performs preliminary scanning of the peripheral regions before scanning the foveal region. By the time the laser reaches the fovea, the patient's eye has already been trained to fixate on that region, and the peripheral data has been collected, ensuring stability during the most critical scanning phase
2Productivity
If visible light is used to perform the scan, then the scanning process can be performed, but the patient naturally follows the motion of the laser with their eye, causing movement
Solution Approach 1:
The patent converts the harmful effect of the patient's natural tendency to follow the laser into a beneficial effect by designing the scan pattern to end at the fovea. The patient's fixation response, which normally causes instability, is now used to stabilize the eye during the final scanning phase, transforming a source of error into a source of stability
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 enables the production of reliable, repeatable, and accurate OCT scans by discouraging the patient from tracking the laser, thereby maintaining stability and improving image quality.
Implementation Method 1
Optical coherence tomography is a technique by which a partially transparent object, such as an eye, may be scanned in three dimensions using interferometric techniques to build up a complete three dimensional volume image of the eye
Implementation Method 2
a sample beam from an interferometer defines a coherence gate in the region where the optical path difference is less than the coherence length
Data Source
AI summary
A method of building up a three dimensional OCT image of an object having a limited region sensitive to movement of a scanning beam performs an OCT scan in a scanning pattern that results in said limited region, typically the fovea of the eye, being scanned last.