Area-Modulated Perimetry for Subtle Visual Field Changes
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Solution Overview
Problem
Existing perimetry methods lack sensitivity to subtle changes in visual function, exhibit high test-retest variability, and are unable to measure functional loss in advanced diseases like glaucoma and AMD due to a limited dynamic range.
Innovation Solution
A method and instrument that utilize fixed-luminance, area-modulated stimuli to measure visual field sensitivity by presenting stimuli of varying sizes, recording responses, and comparing them with age-matched norms or baselines to identify changes in visual pathway function or disease, incorporating spatial and temporal summation principles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard automated perimetry with fixed-area luminance-modulated stimuli is used, then the measurement process is simple and widely applicable, but the sensitivity to subtle changes in visual function is insufficient and test-retest variability is high
Solution Approach 1:
The patent applies dynamics by transitioning from fixed-area stimuli to area-modulated stimuli where the stimulus size dynamically changes during testing. The stimulus area is modulated based on patient responses, allowing the system to adaptively probe visual sensitivity at different spatial scales and detect subtle functional changes that static stimuli cannot capture.
Solution Approach 2:
The patent implements parameter changes by varying the stimulus area parameter while maintaining fixed luminance. This approach changes the physical parameters of the stimulus (area rather than intensity) to overcome the limitations of conventional perimetry, enabling detection of subtle visual function changes through spatial summation effects.
2Reliability
If conventional perimetry methods are used, then the testing procedure is straightforward, but the ability to detect functional loss in advanced diseases like glaucoma and AMD is limited due to restricted dynamic range
Solution Approach 1:
The patent introduces another dimension by adding area modulation to the traditional luminance-modulation approach. This creates a two-dimensional stimulus space (luminance and area) that provides greater dynamic range and sensitivity for detecting visual function loss in advanced diseases, overcoming the limitations of single-parameter conventional perimetry.
Solution Approach 2:
The patent applies segmentation by dividing the visual field assessment into multiple stimulus areas rather than using a single fixed area. This allows independent measurement of visual sensitivity at different spatial scales, providing segmented data that reveals subtle functional changes across various receptive field sizes and improves detection reliability.
3Measurement precision
If fixed-luminance area-modulated stimuli are used, then sensitivity to subtle visual changes is improved, but the device complexity and computational requirements increase
Solution Approach 1:
The patent implements feedback by using patient responses to area-modulated stimuli to guide subsequent stimulus presentation. The system adjusts the stimulus area based on detected thresholds and patient responses, creating a closed-loop measurement process that optimizes sensitivity while managing computational complexity through adaptive algorithms.
Data Source
AI summary
The present invention is concerned with a method and an instrument for measuring visual field sensitivity wherein the method relies on measuring, across a subject's visual field, the subject's response to a fixed-luminance stimulus, the area of which is modulated on subsequent stimulation; and said instrument is adapted to emit, at one or more locations across a subject's visual field, a fixed-luminance stimulus whose area is modulated on subsequent stimulation and wherein the instrument is also adapted to record the subject's response to said fixed-luminance stimulus by comparing the subject's response with the response in an age-matched normal group or by comparing the response to a prior determined baseline in order to identify any change in visual field sensitivity.