Choroid Vascular Perfusion Density Measurement via OCT
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Solution Overview
Problem
Current methods for measuring sympathetic nervous system activity are invasive, difficult to interpret, and lack sensitivity and temporal resolution, making it challenging to assess its effects on autonomic control and vascular regulation in various diseases and physiological states.
Innovation Solution
The use of optical coherence tomography (OCT) to image the choroid vasculature in the human eye, allowing for non-invasive measurement of vascular perfusion density (VPD), which is directly related to sympathetic nervous system activity, enabling comparison of pre- and post-stimuli measurements to assess sympathetic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microneurography is used to directly record sympathetic nervous system activity, then sensitivity and reproducibility are improved, but the technique becomes invasive and may induce vaso-vagal response that compromises interpretation
Solution Approach 1:
The patent uses the choroid vasculature as an intermediary medium to indirectly measure sympathetic nervous system activity. Instead of directly recording from sympathetic nerves (microneurography), the system measures blood flow changes in the choroid, which are controlled by sympathetic tone. This intermediary approach eliminates the need for needle insertion while preserving the ability to detect sympathetic activity through its effect on vascular perfusion.
Solution Approach 2:
The patent replaces the mechanical needle insertion method of microneurography with a non-invasive optical imaging system (OCT). The mechanical intrusion of needles into nerves is substituted by using light to image blood flow in the choroid, thereby eliminating tissue damage and vaso-vagal responses while maintaining measurement capability.
2Measurement precision
If radiolabeled techniques are used to measure sympathetic nervous system activity, then sensitivity is improved, but device complexity and difficulty of routine use increase
Solution Approach 1:
The patent employs a standard OCT imaging system that is already widely available in clinical settings, replacing complex radiolabeled techniques with a simple, routine optical imaging modality. The system uses endogenous contrast (blood flow in choroid vessels) rather than exogenous radiolabels, eliminating the need for specialized radioactive materials and complex handling procedures.
Solution Approach 2:
The choroid vasculature serves as its own contrast mechanism through natural blood flow. The OCT system detects intrinsic optical properties of flowing blood in the choroid, eliminating the need for external radiolabels or contrast agents. This self-service approach simplifies the measurement system while maintaining sensitivity to sympathetic activity.
3Measurement precision
If norepinephrine concentration measurement is used, then sympathetic nervous system activity is assessed, but temporal resolution and sensitivity to moment-by-moment changes are reduced
Solution Approach 1:
The OCT system performs rapid sequential imaging of the choroid vasculature, capturing dynamic blood flow changes at high temporal resolution. This periodic optical sampling allows detection of moment-by-moment fluctuations in sympathetic activity, unlike slower biochemical assays that measure averaged norepinephrine concentrations over time.
Solution Approach 2:
The patent replaces slow biochemical measurement of norepinephrine concentrations with rapid optical imaging of choroid blood flow. The mechanical/chemical process of collecting and analyzing blood or urine samples is substituted by non-invasive light-based imaging that provides real-time visualization of vascular perfusion changes reflecting sympathetic activity.
4Ease of operation
If beat-to-beat cardiac R-R interval variation is measured, then sympathetic nervous system activity is assessed, but the ability to differentiate parasympathetic or sympathetic influence is lost
Solution Approach 1:
The patent targets a specific local vascular bed (choroid) that is known to be under predominant sympathetic control, rather than measuring global cardiac parameters influenced by both sympathetic and parasympathetic systems. By focusing on the choroid vasculature, the system obtains localized information that specifically reflects sympathetic tone without the confounding dual innervation of the heart.
Solution Approach 2:
The patent extracts the measurement from the complex dual-innervated cardiac system and relocates it to the choroid vasculature, which is selectively controlled by sympathetic nerves. This extraction separates the sympathetic signal from the mixed autonomic influences present in cardiac R-R interval measurements, providing cleaner sympathetic-specific data.
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
Provides a reliable, time-sensitive, and non-invasive method for measuring sympathetic nervous system activity, allowing for the disentanglement of sympathetic and autoregulatory effects, with stable and reproducible results, suitable for both clinical and research applications.
Implementation Method 1
The use of optical coherence tomography (OCT) to image the choroid vasculature in the human eye
Data Source
AI summary
Systems and methods for use in measuring sympathetic nervous system activity or blood vessel autoregulation corrected for sympathetic activity. The choroid in the human eye is imaged and, using the resulting image, the vascular perfusion density (VPD) in the choroid is measured. VPD provides a measurement that is directly related to sympathetic nervous system activity. The effect of stimuli on sympathetic nervous system activity can be measured by comparing pre-stimuli VPD measurements with post-stimuli measurements. Quantifying VPD can be performed by determining pixel density within specific areas of the choroid image. Altered sympathetic nervous system activity can be detected in a subject by comparing that subject's VPD measurements to baseline VPD measurements from healthy individuals. Blood vessel autoregulation can be measured by imaging changes in other blood vessels in the eye and correcting with choroid VPD measurements of sympathetic activity.