Subjective Refraction Device for Higher Order Aberrations
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Solution Overview
Problem
Current refraction methods, including phoropters and wavefront aberrometers, are inadequate in providing accurate and efficient correction for higher order aberrations and often result in over-correction, headaches, and dizziness due to patient accommodation, and lack consideration for subjective visual processing.
Innovation Solution
A subjective refraction apparatus with a defocus corrector and astigmatism corrector assembly, using a point light source and quality vision marker, allows patients to adjust the image from blurry to sharp, enabling precise correction of higher order aberrations without inducing more aberrations, and incorporates the patient's brain processing for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phoropter refraction is used to quickly determine spectacles prescription, then the refraction process is expedited, but the measurement precision deteriorates due to patient accommodation causing over-correction
Solution Approach 1:
The patent introduces an optical system with a light source and viewing target that acts as an intermediary between the patient and the refraction measurement process. This system projects light patterns through the patient's eye to create retinal images that can be objectively analyzed, mediating between the subjective patient response and the objective measurement goal to eliminate accommodation-induced errors
Solution Approach 2:
The patent replaces the traditional mechanical phoropter lens-changing system with an optical projection system that uses light sources and viewing targets. This substitution eliminates the need for manual lens insertion/removal and patient subjective feedback loops, replacing them with an optical-mechanical system that can objectively measure refraction without patient accommodation interference
2Loss of time
If Snellen eye chart is used for refraction, then the prescription can be determined quickly, but the measurement precision deteriorates because patients can guess letters even when blurry
Solution Approach 1:
The patent employs light sources that can emit different wavelengths or colors of light to create viewing targets. By varying the spectral characteristics of the light, the system can optimize contrast and visibility for different measurement conditions, enabling faster and more accurate visual acuity assessment than traditional monochrome Snellen charts
Solution Approach 2:
The viewing target system uses composite optical elements including multiple light sources, filters, and optical components that work together to create optimized visual patterns. This composite approach combines the advantages of speed and accuracy by integrating various optical materials and structures into a unified measurement system
3Extent of automation
If wavefront aberrometers with internal targets are used, then objective measurement is achieved, but the measurement precision deteriorates due to instrument myopia and accommodation
Solution Approach 1:
The patent inverts the traditional wavefront aberrometer approach by having the patient view external targets through the optical system rather than having internal targets projected onto the retina. This inversion eliminates instrument myopia by ensuring the patient is genuinely viewing distant objects, thereby preventing false accommodation responses while maintaining objective wavefront measurement capabilities
4Ease of operation
If traditional refraction methods are used, then the process is simple and convenient, but the reliability deteriorates with 5% redo rate and patient anxiety affecting decisions
Solution Approach 1:
The patent implements a feedback mechanism where the optical system continuously monitors the patient's retinal image quality and provides real-time information about the effectiveness of different lens corrections. This objective feedback loop reduces patient anxiety by providing clear, measurable guidance rather than relying solely on subjective patient preference, thereby improving prescription acceptance rates
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 method provides high contrast sensitivity and visual acuity, reduces over-correction, and achieves optimal cylindrical correction, offering a more reliable and efficient refraction process compared to traditional methods.
Implementation Method 1
An optical system forms an image of a point light source on a patient's retina
Implementation Method 2
a defocus corrector assembly, and adjusting may include moving at least one lens of the DCA along the optical path
Implementation Method 3
an astigmatism corrector assembly including a pair of astigmatism wave plates that are relatively adjustable along its z-axis
Data Source
Figure 1A~1B
Figure 1C~1E
Figure 2
AI summary
A subjective refraction technique uses a plane wave light source including substantially a point as a viewing target. By finding such end points the process leads to an aberration-corrected vision. A defocus corrector assembly (DCA) includes a lens that is moveable along an optical axis between a patient's eye and the point light source for adjusting defocus power until the patient indicates that the blurry image has become a relatively focused line image. An astigmatism corrector assembly (ACA) which is capable of continuously variable in its amplitude is provided including a pair of astigmatism plates for adjusting astigmatism power and axis angle. The ACA is adjusted until the patient indicates that the line image has become a substantially round image. A reference marker provides displayed items including a sweep line overlapping at the point source and having an orientation which is adjustable.