Non-Mydriatic Fundus Imaging With Global-Shutter CMOS Capture
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Solution Overview
Problem
Current fundus imaging techniques suffer from low sensitivity, demosaic artifacts, and require pupil dilation, which is uncomfortable for patients and complicates diagnostic procedures.
Innovation Solution
A non-mydriatic fundus imaging system using a monochrome CMOS sensor with global shutter and a three-color LED illumination, eliminating the need for pupil dilation and improving image quality by reducing exposure time and using a global shutter to capture high-quality images without Bayer filter artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a Bayer-patterned color filter array imaging sensor is used, then color information is captured, but sensitivity is low and demosaic artifacts occur
Solution Approach 1:
The patent segments the color filtering function into multiple separate monochrome sensors, each equipped with its own color filter array. This allows each sensor to capture light without the demosaic artifacts that plague single-sensor Bayer patterns, while still achieving full color information through computational merging of the segmented sensor outputs.
Solution Approach 2:
The patent transitions from a single 2D sensor plane to a multi-sensor arrangement that adds a spatial dimension to color capture. By distributing color-filtered measurements across multiple sensor elements in specific geometric patterns, the system achieves higher effective resolution and eliminates the interpolation artifacts inherent in conventional Bayer patterns.
2Ease of operation
If pupil dilation is performed, then fundus imaging is possible, but patient comfort decreases and diagnostic procedure complexity increases
Solution Approach 1:
The patent employs periodic, high-intensity flash illumination to temporarily override the pupil's light reflex. By delivering brief, intense light pulses synchronized with the camera exposure, the system achieves adequate illumination for imaging without requiring sustained pupil dilation, thereby maintaining patient comfort while ensuring imaging capability.
Solution Approach 2:
The system performs preliminary pupil assessment and adjusts illumination parameters accordingly. By pre-evaluating pupil size and adapting the flash intensity and duration before the actual capture, the system ensures adequate lighting conditions are met without unnecessary or excessive illumination that would compromise patient comfort.
3Illumination intensity
If flash mode operation with high intensity is achieved, then sufficient illumination is provided, but patient discomfort increases
Solution Approach 1:
The patent uses periodic flash illumination with precisely controlled duration and timing. By delivering high-intensity light in brief, periodic bursts synchronized with the camera's exposure window rather than continuous illumination, the system achieves necessary lighting levels while minimizing the cumulative light exposure that causes patient discomfort.
Solution Approach 2:
The illumination system dynamically adjusts flash intensity and duration based on real-time conditions such as pupil size, ambient light levels, and distance to the fundus. This dynamic control ensures that high intensity is applied only when and where necessary, reducing overall light exposure and patient discomfort while maintaining adequate illumination for image capture.
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 system enhances diabetic retinopathy screening sensitivity by reducing false negatives and positives, providing sharper images with improved contrast and uniformity, while eliminating the need for pupil dilation.
Implementation Method 1
a light emitting diode arrangement comprising multiple LEDs of different wavelength ranges
Implementation Method 2
High-intensity flash mode operation of a LED can be achieved by applying to the LED a controllable 'pumping'
Implementation Method 3
directing light returned from the illuminated region to a monochromatic CMOS
Data Source
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AI summary
A fundus imaging system includes: an image sensor array, where the image sensor array includes monochrome photodiodes and global shutter control, an illumination unit with one or more light-emitting diodes that have one or more dies, a computing system including a processor and memory, one or more lenses, one or more reflective mirrors, and a display. In an example method of use, a clinician positions a patient, initiates a focal adjustment, initiates a retinal imaging process, and the same or a different clinician views the image. In some embodiments, the imaging system is configured to analyze the image and identify detected physical attributes in the image relating to the diagnosis and treatment of diabetic retinopathy.