Smartphone Camera Layout for Dilation-Free Eccentric Photorefraction
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Solution Overview
Problem
Existing smartphone cameras are not optimally configured for accurate eccentric photorefraction, limiting their ability to detect a wide range of refractive errors, especially low ametropia and hyperopia, and require pupil dilation, making them unsuitable for young children and inconvenient for general use.
Innovation Solution
A smartphone-based camera system with a specific lens array and LED flash configuration, combined with machine learning algorithms, captures images of the eye's retinal reflex to estimate refractive errors without dilation, using eccentric photorefraction principles to detect myopia, hyperopia, and astigmatism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photorefraction techniques are used with standard smartphone cameras, then the device is portable and cost-effective, but the measurement precision is limited and cannot detect low refractive errors
Solution Approach 1:
The patent applies asymmetry by positioning the flash unit offset from the camera lens axis, creating an eccentric photorefraction geometry. This asymmetric configuration allows light to reflect off the retina at an angle, producing a crescent-shaped reflex that enables detection of low refractive errors that would be invisible with symmetric on-axis lighting
Solution Approach 2:
The patent implements local quality by using specific optical parameters at different locations in the system - the flash is positioned at a specific eccentric distance from the lens, and the aperture is set to a specific f-stop value. These localized optical conditions create the precise crescent reflex geometry needed for accurate low-ametropia detection
2Measurement precision
If pupil dilation is required for accurate photorefraction, then the measurement precision improves, but the ease of operation deteriorates and the procedure becomes unsuitable for young children
Solution Approach 1:
The patent changes the optical parameters of the measurement system - specifically using an eccentric flash position and optimized aperture settings - to achieve accurate refractive error detection without requiring pupil dilation. This parameter optimization allows the system to work effectively with natural pupil sizes
Solution Approach 2:
The patent captures the retinal reflex as a two-dimensional image pattern that can be analyzed computationally. By copying the optical information into an image format, the system can perform precise measurements without needing to physically manipulate the pupil or use complex optical arrangements
3Measurement precision
If standard smartphone camera configurations are used, then the device is simple and widely available, but the measurement precision is insufficient for detecting low ametropia and hyperopia
Solution Approach 1:
The patent optimizes specific parameters of the smartphone camera system - flash-to-lens distance, aperture f-stop value, and focal length - to achieve high measurement precision. These parameter adjustments transform a standard consumer device into a precision measurement instrument without requiring custom hardware
Solution Approach 2:
The patent uses the smartphone camera to capture an optical copy of the retinal reflex. This digital copy can be processed and analyzed to detect refractive errors with high precision, leveraging the computational power of mobile devices to achieve clinical-grade measurements
4Measurement precision
If conventional autorefractors are used, then the measurement precision is high, but the device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex clinical instruments with a smartphone-based system that captures retinal reflex images. By copying the essential optical measurement function into a mobile device, the system achieves comparable measurement precision without the bulk, cost, and complexity of traditional autorefractors
Solution Approach 2:
The patent substitutes mechanical and optical complexity with computational simplicity. Instead of using complex mechanical adjustment mechanisms and multiple optical components found in conventional autorefractors, the system uses a fixed smartphone camera configuration with image processing algorithms to achieve high measurement precision
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
Provides a cost-effective, user-friendly method for refractive error detection suitable for children and remote areas, covering a wide range of refractive errors with high accuracy and precision, eliminating the need for pupil dilation.
Implementation Method 1
an light source such as an LED or infra-red flash configured to provide an illumination beam
Implementation Method 2
Light rays from a camera flash are reflected by the retina, forming a bright red crescent-shaped light reflex
Implementation Method 3
Light rays from a camera flash are reflected by the retina... The general optical principles of eccentric photorefraction are well known in the art
Implementation Method 4
one or more lenses spaced apart, which are configured to capture simultaneous still and/or video images
Data Source
AI summary
A camera system on mobile device for automatic eccentric photorefraction to measure potential refraction errors in the human eye. A mobile device such as a smartphone has one or more lenses and one or more illuminators which are used to create, capture, and measure red eye reflexes. The red eye reflex measurements are then used with a machine learning algorithm to determine if refractory error is present in the eye.