Ophthalmic Pupil Alignment for Ultra-Widefield Fundus Imaging
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Solution Overview
Problem
Ophthalmic imaging scanners face challenges in accurately aligning the pupil of the eye with the exit pupil to capture high-quality ultra-widefield fundus images, particularly in widefield and ultra-widefield imaging, due to varying angles of incidence and the need for precise pupil positioning.
Innovation Solution
An ultra-widefield ophthalmic imaging instrument with a patient alignment device that monitors the pupil position relative to the exit pupil, adjusts the range of acceptable distances based on pupil size, and generates guidance signals to align the pupil within the optimal distance range, followed by automatic image acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If stereoscopic ranging techniques with fixed range thresholds are used to guide pupil alignment, then the alignment process can be automated, but the system cannot adapt to different pupil sizes leading to inaccurate alignment for some patients
Solution Approach 1:
The patent implements dynamic adjustment of the acceptable pupil distance range based on real-time detection of pupil size. The system continuously monitors pupil diameter and automatically modifies the threshold values for acceptable pupil position accordingly. This dynamic adaptation allows the automated alignment system to accommodate varying pupil sizes across different patients and lighting conditions, resolving the contradiction between automation and adaptability.
2Ease of operation
If a fixed range of distances from the exit pupil is used for all patients, then the alignment process is simplified, but high-quality ultra-widefield images cannot be acquired for patients with different pupil sizes
Solution Approach 1:
The system maintains operational simplicity by automatically adjusting the acceptable distance range based on detected pupil size. Rather than requiring manual configuration or complex user intervention, the system dynamically modifies its acceptance criteria in real-time based on optical feedback from the patient's pupil. This preserves ease of operation while ensuring image quality across diverse patient populations.
Solution Approach 2:
The alignment system performs self-adjustment by automatically detecting pupil size and modifying the acceptable distance range without requiring external input or manual calibration. The system serves itself by using its own measurement capabilities to adapt its operational parameters, thereby maintaining simplicity while achieving precise alignment for each individual patient.
3Adaptability or versatility
If manual pupil alignment guidance is provided to patients, then the system can accommodate various pupil positions, but the image acquisition process becomes time-consuming
Solution Approach 1:
The system implements automated feedback control by continuously monitoring pupil position and distance, comparing it against dynamically adjusted acceptable ranges, and providing real-time guidance to the patient. This closed-loop feedback system automatically adapts to various pupil positions and guides the patient into the optimal position, eliminating manual intervention while maintaining high acquisition speed.
Solution Approach 2:
The system automatically modifies the acceptable distance parameters based on detected pupil characteristics. By changing the reference parameters dynamically rather than requiring manual adjustment, the system can quickly adapt to different pupil positions and sizes, thereby maintaining high productivity while accommodating patient variability.
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
Facilitates quick and comfortable capture of high-quality ultra-widefield fundus images by ensuring precise pupil alignment, reducing clipping and enhancing image coverage.
Implementation Method 1
Stereoscopic ranging techniques employing stereo cameras are often used to measure distance to the eye. For example, some ophthalmic imaging scanners include a so-called pupil alignment module (PAM), which comprises stereo cameras to acquire stereo images of the eye, and is arranged to determine the distance between the PAM and the pupil based on a separation between the pupil centres in the stereo images.
Data Source
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AI summary
An ultra-widefield ophthalmic imaging instrument which acquires an ultra-widefield image of a fundus of a subject's eye, comprising: a patient alignment device which monitors a position of a pupil of the eye relative to an exit pupil of the instrument, and compares the position with a range of distances from the exit pupil to determine whether the pupil is within the range of distances, the range being adjustable. If the pupil is outside the range of distances, the patient alignment device generates, based on the monitored position, signals for guiding the subject to vary a distance between the eye and the instrument to bring the pupil towards the range. If the pupil is within the range of distances, the patient alignment device generates an indication that the pupil is at a position suitable for acquiring the image. The instrument acquires the image automatically in response to the indication being generated.