Split-Prism Rangefinder for OCT Eye Movement Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current eye measurement systems, particularly OCT systems, face challenges in combining data from successive measurements due to eye movement, with short coherence lengths and high costs associated with longer coherence length solutions like SS-OCT systems.
Innovation Solution
A split-prism rangefinder system that uses a light source to produce a linear shape, directing light to the eye and splitting returned light into segments imaged on an image sensor, allowing for determination of eye movement between measurements, enabling accurate combination of data without the need for expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If SD-OCT systems with short coherence length are used, then cost is reduced, but measurement precision deteriorates due to inability to measure entire eye length and sensitivity to eye movement
Solution Approach 1:
The patent divides the eye measurement into multiple sequential segments (first portion and second portion) measured at different times. The SD-OCT system measures the first portion, then the reference length is adjusted to measure the second portion. This segmentation allows the use of lower-cost SD-OCT systems with shorter coherence lengths while still achieving complete eye measurement through combination of multiple scans.
Solution Approach 2:
The patent employs a feedback mechanism using an eye position sensor (such as a split-prism rangefinder or infrared camera) that continuously monitors eye position and provides real-time feedback. This feedback is used to detect and compensate for eye movements between scans, allowing accurate combination of measurements from multiple time points despite patient motion.
2Adaptability or versatility
If multiple OCT scans are taken at different reference lengths, then complete eye measurement is achieved, but measurement precision deteriorates due to eye movement between scans
Solution Approach 1:
An eye position sensing system provides real-time feedback on eye position changes between scans. The system uses this feedback information to geometrically transform and register the first and second OCT measurements, compensating for eye movements and enabling accurate combination of data from different reference lengths despite temporal separation.
Solution Approach 2:
The patent replaces mechanical stabilization methods (such as chin rests or head holders) with an optical/electronic eye position detection and computational correction system. Instead of physically preventing eye movement, the system uses light-based sensors to detect movement and applies mathematical transformations to correct the measurements, achieving more precise and comfortable measurement.
3Measurement precision
If SS-OCT systems with long coherence length are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the measurement task into multiple SD-OCT scans at different reference lengths, avoiding the need for a single long-coherence SS-OCT system. This segmentation strategy achieves complete eye coverage using simpler, lower-cost SD-OCT technology while maintaining measurement precision through computational methods.
Solution Approach 2:
The patent introduces an eye position sensor and computational processing system as intermediaries between the SD-OCT scanner and the final measurement result. This intermediary system bridges the gap caused by the short coherence length, enabling accurate measurements without requiring complex SS-OCT hardware.
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
Enables accurate and cost-effective measurement of eye movement and data combination, improving the precision of eye measurements by compensating for movement during OCT scans, thus overcoming the limitations of short coherence lengths.
Implementation Method 1
receive returned light from the eye
Implementation Method 2
split-prism rangefinder configured to receive the returned light and to determine a distance the eye moved based on a change in the linear shape of the returned light which is imaged onto the image sensor
Implementation Method 3
imaged onto the image sensor
Data Source
AI summary
A measurement instrument and method: produce light having a linear shape; direct the light toward an eye and provide returned light, having the linear shape, from the eye to a split-prism; split the returned light into first and second linear segments and image them onto an image sensor; determine a first lateral offset between the first and second linear segments on the image sensor at a first time; determine a second lateral offset between them at a second time; determine a difference between the first and second lateral offsets; determine a distance that the eye moved relative to the first lens between the first time and the second time based on the difference between the first and second lateral offsets; perform optical coherence tomographer (OCT) measurements at the first and second times; and combine the OCT measurements while compensating for eye movement based on the determined eye movement.