# High-Resolution Flow Imaging of Optic Nerve Head and Retrolaminar Microvascular Circulation

> **NIH NIH R01** · UNIVERSITY OF SOUTHERN CALIFORNIA · 2023 · $739,083

## Abstract

Glaucoma is a leading cause of irreversible blindness worldwide, affecting over 2.2 million Americans. Although elevated
intraocular pressure (IOP) is the primary risk factor for the development of the disease, the mechanisms by which elevated
IOP eventually leads to damage and loss of neural flow function for optic never head (ONH) are still unclear. It is also
unclear how sensitivity to IOP varies and interacts with other risk factors for glaucoma, such as aging and race. ONH is the
principal site of damage in glaucoma, and the blood flow in the ONH and its perfusion directly related retrobulbar circulation
have been recognized as an important role in glaucoma patients, particularly in a subgroup of primary open-angle glaucoma
and normal-tension glaucoma. Currently, optical coherence tomography (OCT) and its angiographic extension (OCT-A)
are, at present, clinically accepted technologies for ophthalmic imaging. Previous OCT systems were able to demonstrate
blood-flow in two-dimensional B-scan images based on decorrelation and/or Doppler effects, this capability excited minimal
interest. It was only with the development of high-speed OCT systems that could acquire multiple 3D scans fast enough to
produce en-face images of the retinal/choroidal vasculature that OCT-A became in short order a standard ophthalmic
imaging clinical modality, even replacing fluorescein angiography to a great extent. A limitation of OCT, however, it is its
inability to image ONH and posterior segment of eye that beyond the opaque sclera tissue due to limitation of OCT
penetration. Instead, ultrasound color Doppler methods have long offered a means for visualizing and characterizing flow,
even in optically inaccessible areas such as the ONH and posterior pole of the eye. However, the spatial resolution of
conventional line-by-line scan ultrasound imaging is fundamentally hindered by the diffraction limit of the ultrasound wave,
resulting in less ability to characterize the fine vasculature network of the deep eye. Since ultrasound contrast agents such
as microbubble are much smaller than the wavelength of ultrasound, acquisition and localization of successive ultrafast
frames containing microbubbles may provide an opportunity to reconstruct and map both flow velocity and microvessel
density map with a ten-fold resolution improvement than conventional ultrasound imaging, which is defined as super-
resolution ultrasound microvessel imaging herein. In this proposal, we will develop high frequency ultrasonic 2D array with
frequencies in the range from 15 to 20 MHz which will be interfaced to a fully configurable ultrasound imaging system
(Verasonics, Kirkland, WA). The combination of novel compounding plane wave image technology and 3D ultrasound
microbubble localization/tracking algorithm will be able to provide high-resolution microvessel blood flow imaging of ONH
and retrobulbar circulation. We have three aims: 1) Fabricate high-frequency 2D array and integrate 2D array w...

## Key facts

- **NIH application ID:** 10649225
- **Project number:** 1R01EY035084-01
- **Recipient organization:** UNIVERSITY OF SOUTHERN CALIFORNIA
- **Principal Investigator:** Shigao Chen
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $739,083
- **Award type:** 1
- **Project period:** 2023-09-30 → 2027-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10649225

## Citation

> US National Institutes of Health, RePORTER application 10649225, High-Resolution Flow Imaging of Optic Nerve Head and Retrolaminar Microvascular Circulation (1R01EY035084-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10649225. Licensed CC0.

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