Smartphone Wide-Field Fundus Camera Optical Layout
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Solution Overview
Problem
Existing smartphone fundus cameras have limited field of view (FOV) and are costly, making them unsuitable for wide-field fundus imaging in rural and underserved areas where skilled operators and expensive instruments are scarce.
Innovation Solution
A miniaturized wide-field fundus indirect ophthalmoscopy method and apparatus using a smartphone with a unique optical layout, including a high numeric aperture lens and relay lens, allowing for both snapshot photography and video recording with a FOV of up to 92°, and a non-mydriatic version achieving 67° FOV without pharmacological dilation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If BIO lenses are used in smartphone fundus cameras, then cost is reduced, but field of view is limited to less than 45°
Solution Approach 1:
The imaging system is divided into two separate lenses: a first lens (60D) for illumination and a second lens (20D) for imaging. This segmentation allows each lens to be optimized for its specific function, enabling a wider field of view while maintaining cost-effectiveness through the use of standard optical components.
Solution Approach 2:
A beam splitter is introduced as an intermediary component that separates the illumination light path from the imaging light path. This allows the illumination system and imaging system to operate independently while sharing the same optical axis, enabling wider FOV without requiring complex integrated lens designs.
2Area of stationary object
If trans-palpebral illumination is employed, then field of view increases to about 152°, but device complexity increases due to separate adjustment of imaging and illumination sub-systems
Solution Approach 1:
The illumination and imaging functions are merged into a single integrated optical system where both the first lens (60D) and second lens (20D) work together through a shared optical axis. The beam splitter enables simultaneous illumination and imaging without requiring separate adjustment mechanisms, simplifying operation while maintaining wide FOV capability.
3Reliability
If conventional fundus cameras are used, then imaging quality is maintained, but equipment cost is high
Solution Approach 1:
The system uses relatively inexpensive standard optical lenses (60D and 20D) rather than specialized expensive fundus camera optics. While individual lens components are simpler and less costly, their coordinated arrangement through the beam splitter configuration achieves clinical-grade imaging quality suitable for diabetic retinopathy screening.
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
Enables affordable, portable, and easy-to-use wide-field fundus imaging and video recording, facilitating remote expert involvement and increasing effective FOV beyond 180°, suitable for point-of-care and telemedicine applications in resource-constrained settings.
Implementation Method 1
an illumination subsystem including a first lens (60D) and a light source, and an imaging subsystem including a second lens (20D) and a camera sensor
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
A wide-field fundus indirect ophthalmoscopy method and apparatus are provided that can be miniaturized to be suitable for employment in a smartphone and that overcome limitations of existing smartphone wide field fundus imaging devices and methods, such as high cost, clinical deployment challenges and limited field of view. The wide-field fundus indirect ophthalmoscopy method and apparatus are also well suited for use in rural and underserved areas where both expensive instruments and skilled operators are typically not available. The wide-field fundus indirect ophthalmoscopy method and apparatus enable wide-field snapshot fundus images to be captured with wide fields of view (FOV) under mydriatic and non-mydriatic conditions and also enables video recordings of the fundus to be captured from which montages can be constructed with even wider FOVs.