Visual Field Testing Fixation Loss Switch
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Solution Overview
Problem
Conventional visual field testing methods suffer from false positive and false negative results due to patient fixation loss and reduced concentration, making it difficult for practitioners to accurately analyze test reliability, and existing solutions either fail to detect false negatives or increase data processing burdens.
Innovation Solution
A visual field testing apparatus and method that records patient responses and includes a fixation loss switch to identify periods of fixation loss in real-time, allowing for immediate identification of unreliable results and reducing the need for extensive post-test analysis, while minimizing observer burden and data storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If video recording of the patient's eye is taken during the visual field test to assess fixation reliability, then the reliability of test results can be assessed, but the data processing burden and file sizes increase significantly
Solution Approach 1:
The patent extracts only the essential information needed for reliability assessment - specifically timing data of fixation loss events - from the complex video recording process. Instead of storing and analyzing entire video files, the system extracts temporal information about when fixation was lost, reducing data processing requirements while maintaining the ability to assess test result reliability
Solution Approach 2:
The patent introduces an intermediary mechanism (fixation loss switch) that mediates between the complex video recording system and the final reliability assessment. This switch captures essential timing information without requiring full video analysis, acting as a simplified interface that preserves reliability information while eliminating excessive data processing requirements
2Measurement precision
If video recording is reviewed to identify false positive results, then fixation accuracy can be determined, but the time taken by practitioners to examine results increases significantly
Solution Approach 1:
The patent performs preliminary action by automatically recording timing data of fixation loss events during the test itself. This pre-processing of reliability information eliminates the need for practitioners to manually review video recordings after the test, as the essential fixation accuracy information has already been captured and stored in a readily analyzable format
Solution Approach 2:
The patent replaces the mechanical process of manual video review with an automated timing-based system. Instead of practitioners watching video recordings to determine fixation accuracy, the system automatically records and analyzes timing data from fixation loss events, substituting manual examination with automated temporal analysis
3Reliability
If blind spot targets are presented to assess fixation loss, then general indication of reliability can be obtained, but the reliability of each individual field test target result cannot be indicated
Solution Approach 1:
The patent segments the reliability assessment into individual target-specific evaluations. Instead of providing only a general reliability indication from blind spot targets, the system divides the assessment into discrete time intervals corresponding to each visual field target presentation, allowing practitioners to determine the reliability of each individual target result separately based on fixation loss timing data
Data Source
AI summary
Apparatus for testing a patient's visual field, the apparatus comprising: means for recording the results of the patient's responses to one or more visual field targets (5) presented during a visual field test; and a fixation loss switch activatable by an observer observing the patient during the visual field test for identifying periods of fixation loss by the patient. The results recorded during periods of fixation loss are identified as being unreliable. Also disclosed is a method of testing a patient's visual field.