Functional Vision Mobility Testing Across Low Illumination Levels
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Solution Overview
Problem
There is a lack of validated and regulatorily accepted mobility/maze tests for measuring functional outcomes in subjects with degenerative retinal diseases beyond patients with RPE 65 mutations, particularly for conditions like retinitis pigmentosa (RP), limiting the precision in assessing changes in contrast and illumination during maze navigation.
Innovation Solution
A method and system for testing functional vision involving a subject navigating preprinted courses with varying illumination levels and obstacles, using a video recording and analysis to determine critical illumination levels (CIL) and maximum step speeds (MSS) through a series of courses with controlled lighting and obstacle configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mobility test is used to measure functional vision in subjects with retinal dystrophies, then functional outcome measurement is achieved, but measurement precision is insufficient due to lack of validated parameters for contrast and illumination changes
Solution Approach 1:
The patent applies parameter changes by systematically varying illumination levels (13 discrete levels from 0.12 to 500 lux spaced by 0.3 log units) and contrast levels (multiple preprinted courses with different contrast values) to create a standardized mobility test protocol. This allows precise measurement of functional vision by determining the critical illumination level at which navigation performance deteriorates, thereby resolving the contradiction between measurement precision and reliability.
2Measurement precision
If multiple illumination levels are tested to determine critical illumination level, then measurement precision improves, but testing time increases
Solution Approach 1:
The patent applies preliminary action by having subjects complete practice trials at the highest illumination level before formal testing begins. This practice session familiarizes subjects with the maze navigation task and reduces learning effects during actual testing, thereby improving measurement precision without proportionally increasing testing time.
Solution Approach 2:
The patent implements periodic action by testing at 13 discrete illumination levels rather than continuous variation. This periodic sampling approach efficiently captures the critical illumination level where performance deteriorates, balancing measurement precision with acceptable testing time.
3Reliability
If standardized courses with obstacles are used, then reliability of testing improves, but device complexity increases due to multiple courses and obstacle configurations
Solution Approach 1:
The patent applies segmentation by dividing the mobility test into multiple standardized courses, each with specific contrast levels and obstacle configurations. This segmentation allows systematic assessment of navigation performance under different visual conditions while maintaining reliability through standardization, managing complexity through modular course design.
Solution Approach 2:
The patent applies universality by designing a single standardized mobility test system that can assess multiple vision functions (contrast sensitivity, visual field, depth perception, visual acuity) across different illumination levels. This multi-functional approach improves reliability through comprehensive assessment while avoiding the complexity of multiple separate testing devices.
Data Source
AI summary
The present disclosure relates to systems and methods for testing functional vision of a subject. The systems and methods utilize a plurality of obstacle courses, a plurality of contrast levels of the obstacle courses, a plurality of illumination levels, video-recording, and a robust scoring algorithm to assess the mobility of the subject.