Dynamic Fixation Target for Retinal Imaging Alignment
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Solution Overview
Problem
Conventional retinal cameras face challenges in aligning the eye with the imaging system due to small eyeboxes, leading to optical aberrations and image artifacts, which are exacerbated by bright illumination, making high-fidelity retinal imaging difficult and straining for patients.
Innovation Solution
A dynamic fixation target system that adjusts in real-time to aid alignment by providing visual feedback through a display, guiding the patient's eye position relative to the eyepiece lens assembly, using a controller to analyze misalignment and adjust the fixation target to ensure proper alignment within a threshold, thereby reducing image artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bright illumination is used to improve image fidelity, then retinal image quality improves, but optical artifacts such as corneal reflections, iris reflections, or lens flare increase
Solution Approach 1:
The fixation target dynamically changes its displayed content based on the detected eye position. When misalignment is detected, the system presents alignment-guiding content (arrows, directional cues) to guide the patient's eye movement. When aligned, it presents fixation-maintaining content. This dynamic adaptation allows the system to use bright illumination effectively while minimizing optical artifacts through real-time alignment correction.
2Object-generated harmful factors
If the eyebox size is reduced to block image artifacts, then optical artifact reduction improves, but camera alignment difficulty increases
Solution Approach 1:
The system incorporates a camera that continuously monitors the patient's eye position and provides real-time feedback by analyzing pupil center location and gaze direction. This feedback loop enables the fixation target to adapt its displayed content to guide the patient into proper alignment, making the alignment process intuitive and reducing the strain on patients while maintaining a limited eyebox for artifact blocking.
Solution Approach 2:
The fixation target serves as an intermediary element between the patient and the alignment requirements. By displaying directional cues, arrows, or other guiding patterns, it mediates the alignment process, translating the complex optical alignment requirements into simple visual guidance that the patient can follow to achieve proper eye positioning.
3Measurement precision
If mechanical stages are added to automatically adjust alignment, then alignment precision improves, but device complexity and cost increase
Solution Approach 1:
The system replaces complex mechanical alignment stages with a software-based solution. Instead of mechanically moving the camera or optical components to achieve alignment, the system uses a camera to detect eye position and dynamically adjusts the fixation target display content to guide the patient's eye into proper alignment. This substitution of mechanical systems with optical-detection-and-display-control systems reduces device complexity and cost while maintaining alignment precision.
Data Source
AI summary
Retinal imaging systems and methods are described. In an embodiment, the retinal imaging system includes an eyepiece lens assembly; an image sensor adapted to acquire a retinal image of an eye through the eyepiece lens assembly; a dynamic fixation target optically coupled to the eyepiece lens assembly such that the dynamic fixation target is viewable through the eyepiece lens assembly; and a controller communicatively coupled to the image sensor and the dynamic fixation target. In an embodiment, the dynamic fixation target includes a display where an image generated by the display is controlled by a position of a user's eye relative to the eyepiece lens assembly.