Stimulus Eye Tracking System for Optokinetic Nystagmus Detection
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Solution Overview
Problem
Accurate evaluation of visual function in young children is challenging, particularly for healthcare providers without extensive training in pediatric ophthalmology or visual electrophysiology, due to the lack of suitable methods for assessing perceptual aspects of vision like visual acuity and motion perception.
Innovation Solution
A system and method for stimulus and eye tracking that involves displaying a visual stimulus with varying visibility across a display, using elements with contrasting perimeters and centers, and recording eye movements to detect optokinetic nystagmus (OKN) through image processing, allowing for the assessment of OKN presence and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If video-oculography techniques are used to track eye movements and determine OKN, then visual function can be evaluated objectively, but the system becomes complex and difficult to operate for healthcare providers without extensive training
Solution Approach 1:
The patent replaces complex mechanical eye tracking systems with a simplified video-based oculography system that uses standard video cameras and software algorithms to detect OKN. The system substitutes sophisticated hardware with readily available video technology combined with image processing, making the system less complex while maintaining measurement precision for visual function assessment
Solution Approach 2:
The system enables automated detection and analysis of OKN patterns through software algorithms that automatically process video footage and generate diagnostic information. This self-service capability reduces the need for extensive operator training and manual analysis, allowing healthcare providers to obtain accurate visual function assessments without becoming experts in OKN detection techniques
2Reliability
If high contrast drifting patterns are used to elicit OKN, then OKN can be reliably detected, but the stimulus parameters must be precisely controlled and adjusted
Solution Approach 1:
The patent employs systematic variations of stimulus parameters including contrast levels, drift speed, pattern frequency, and coherence to optimize OKN elicitation. By implementing controlled parameter changes and adjusting these variables based on detected OKN responses, the system achieves reliable OKN detection while managing stimulus control complexity through automated parameter adjustment algorithms
3Measurement precision
If the visual stimulus visibility is varied to assess visual function thresholds, then accurate visual acuity measurement is achieved, but the stimulus presentation becomes more complex
Solution Approach 1:
The system implements periodic variation of stimulus visibility using alternating phases of stimulus presentation and occlusion. By systematically cycling the stimulus between visible and hidden states at controlled intervals, the system can determine visual acuity thresholds based on OKN detection during different visibility phases, achieving precise measurement while managing presentation complexity through rhythmic, predictable stimulus patterns
Data Source
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AI summary
A system and method for stimulus & eye tracking, useful for the determination of the presence or strength of optokinetic nystagmus (OKN) typically for assessing visual acuity, comprises providing a novel visual stimulus effective to elicit OKN, which includes varying the visibility of a visual stimulus element, or displaying a series of visual stimulus elements so that a later displayed element has different visibility relative to an earlier displayed element. Visual stimulus elements may vanish or appear by reducing or increasing intensity, contrast, size and/or width of the elements or element boundaries. Visual stimulus elements comprise a perimeter that is darker than a background and a centre that is lighter than the background, and/or a perimeter that is lighter than a background and a centre that is darker than the background.